Product Documentation
Virtuoso ADE Explorer User Guide
Product Version IC23.1, November 2023

9

Plotting and Printing

This chapter shows how to print and plot simulation data.

After the simulation run is complete and results are displayed on the Value column of the Outputs Setup tab (for single-point runs) or on the Result tab (for multi-point runs), you can use the Virtuoso Visualization and Analysis XL tool to plot and analyze these results. If the Plot check box in the Outputs Setup is selected, the results are automatically plotted. If only the Save check box is selected, but the result is a waveform, you can manually plot the output waveform. You can use one of the following ways to select and plot simulation results in the Virtuoso Visualization and Analysis XL graph window:

When you click a terminal, it gets selected first and then the wire gets selected. Therefore, you can now alternate between the two.

If you set up the Outputs Setup tab in ADE Explorer, with nets to be plotted, and click the Plot Outputs icon during an analysis run, the graph window will pop up and plot the outputs.

Therefore, you get a snapshot of the simulation run upto that time point. You can also use the Calculator or the Results Browser to plot outputs.

After loading a maestro cellview if you want to plot the outputs saved in the setup, you need to run a simulation to generate the results. Otherwise, an error message is displayed. Alternatively, you can open a history from the Results – Select menu and plot the outputs.

Setting Plotting Mode

The ADE Explorer provides different plotting modes. You can choose a plotting mode depending on your requirements to save and compare plots of different simulation results.

The Plotting toolbar provides the following two options to choose how to plot the results:

Plotting Mode

You can choose the following plotting modes:

You can select the plotting modes for automatic plotting from the Direct Plot, the Virtuoso Visualization and Analysis XL Calculator and the Results Browser windows also.

ADE Explorer Plotting/Printing Options Form

To set the ADE Explorer printing and plotting options, do one of the following:

You can use this form to set the printing and plotting options.

See the following topics for assistance:

Specifying the Default Plotting Option

You can specify the default plotting option to be used for the automatic plotting of results after a simulation run is complete and also used to specify which plotting option is used when you click the Plot all waveforms button on the Results tab.

To specify the default plotting option,

You can also configure the default plotting option by using the plotType environment variable.

Specifying the Outputs that Need to be Plotted

To specify the outputs that need to be plotted automatically after the simulation finishes, do the following in the Plot group box

Select To

Plot Signals

To plot signals.

Plot Waveform Expressions

To plot expressions that evaluate to waveforms.

Plot Scalar Expressions for Multi-Point Simulation

To plot scalar values for a multi-point simulation.

Specifying the Default Plotting Mode

To specify the default plotting mode, do the following:

Specifying Annotations for the Graph Window

To specify annotations for the graph window, do the following:

  1. Select one or more of the following Annotations check boxes:
    • Design Name — Annotates design name in the title banner of the waveform window.
    • Simulation Date — Annotates date and time of simulation in the title banner of the waveform window.
    • Temperature — Annotates simulation temperature in the plot area of the waveform window.
    • Design Variables — Annotates design variables and their values in the plot area of the waveform window.
    • Scalar Outputs for Single-Point Simulation — Annotates scalar values for a single-point simulation.
    • Spec Markers — Annotates spec markers in the plot area of the waveform window.
  2. Click Apply.

Here is a waveform window with all annotations applied:

Specifying Histogram Options

To specify the histogram options, do the following in the Histogram Options section:

Specifying Maestro Plotting Template Options

To enable or disable default maestro plotting template options, do the following in the Maestro Plotting Template Options group box:

Select

To

Plot Only Matching Leaves

Plot matching leaves with plotting templates.

Create New Strips for New Leaves

Plot new leaves for signals in new strips.

Use Color Bank

Plot signals using the default color bank.

Specifying Whether to Save Quick Plot Data

To save the data for a quick plot, select the Save Quick Plot data check box in the Quick Plot section. This field is enabled by default. When this field is not selected, the Quick Plot option does not work for the output signals or expressions.

Specifying the Default Direct Plot Options

To specify the default direct plot mode options, do the following in the Direct Plot drop-down:

  1. Select the plot mode from the Plotting Mode drop-down list.
    For more information about plot modes, see Plotting Mode.
  2. Select one of the following Direct Plots Done After options:
    • Each Selection – Plot results after each item you select on the schematic.
    • All Selections Are Made – Plot results after you select all items and press Esc to end selection mode.
  3. Click Apply.

Specifying When to Print Results

To specify when to print results to the Results Display Window, do the following:

  1. Select one of the following Print After options:
    • Each Selection – Print results after each item you select on the schematic.
    • All Selections Are Made – Print results after you select all items and press Esc to end selection mode.
  2. Click Apply.

Enabling the Distributed Plot Service

To enable the distributed plot service:

  1. Select the Enable Distributed Plot check box.
  2. (Optional) In the Linger Time (seconds) field, specify the time in seconds for which the distributed plot process waits before exiting when there is no active plotting window is visible. The default value is 60 seconds. It is recommended not to set the linger time to less than 30 seconds.
  3. Click Apply.

Distributed Plot Commands

The following table describes the distributed plot commands that are displayed when you click the arrow next to the icon in the Run toolbar of ADE Explorer.

Command Description

Open Graph

Opens the Distributed Plot graph window.

Job Distribution

Opens the Job Policy Selection for Distributed Plot form. This form lets you select the job policy that you have set up earlier in the Job Policy form.

Show Process List

Displays information about the currently running processes in an xterm window.

Show Assistant

Opens the Distributed Plot assistant. The Distributed Plot assistant lets you view and manage various plotting jobs

Exit

Exits the distributed command menu.

These commands become unavailable if you disable distributed plot. The icon indicates that distributed plot is disabled.

Related Topics

Distributed Plot

Refreshing Graphs

Graphs can be refreshed using the Refresh option in the Plotting Options drop-down box in the ADE Explorer Plotting/Printing Options form. This option updates the open graphs in Virtuoso Visualization and Analysis XL with the new simulation results, and retains the graph and trace settings.

You can use this option to review graphs across different simulation runs. For example, consider you want to run multiple simulations with different values of the design variable CAP. In the first run, plot CAP for 800f. After the simulation results are plotted in the graph, customize the plots, as shown in the figure below.

In the next run, use CAP=200f to run the simulation. Using the Refresh option, the simulation results are updated in the same graph.

The settings done to the plots are retained, as shown in the following figure.

You can use File – Reload to reload the plotted graphs based on the results from a new in-context results directory selected in the Results Browser. If you rerun the simulation even without changing the corner settings, Reload plots traces from all the corners in the graph. To know more, see Reloading Graph When Opened From Within ADE L, ADE XL, ADE Explorer or ADE Assembler in the Virtuoso Visualization and Analysis XL User Guide.

The following sections describe how the graphs are refreshed using the Refresh option in different scenarios:

Graph Settings Supported by the Refresh Plotting Mode

The Virtuoso Visualization and Analysis XL graph window saves and maintains the following settings for the graphs that are generated for a common set of variable combinations across simulation runs:

Graph Settings Not Supported by the Refresh Plotting Mode

Currently, the following graph settings are not supported:

Refresh Plotting with Varying Analysis

The following table describes how graphs are refreshed when analysis are varied across different simulation runs:

Table 9-1 Effect of Analysis Variations on Graph Settings with Refresh Option
Analysis Variation Effect on Graph Settings

Add or enable an analysis
  • A new subwindow is added to the graph to display the plots of the newly added or enabled analysis.
  • Graphs for the analysis that are common across different runs are updated with new simulation data and any trace settings are retained.

Delete or disable an analysis
  • Subwindows related to the analysis that has been deleted or disabled after the previous simulation run, are removed from the graph.

Refresh Plotting with Varying Outputs

The following table describes how graphs are refreshed when outputs are varied across different simulation runs:

Table 9-2 Effect of Output Variations on Graph Settings with Refresh Option
Analysis Variation Effect on Graph Settings

Add or enable an output
  • Plot for the new output is added in a new subwindow.
  • Other existing graphs are refreshed and their trace settings are maintained.

Delete or disable an output
  • The plot for the deleted or disabled output is removed.
  • Other existing graphs are refreshed and their trace settings are maintained.
The Refresh option does not update graphs for MATLAB measurements.

Refresh Plotting with Parametric Simulation

If you perform parametric simulation runs, the graphs are updated with new simulation results for common sweep values between subsequent runs. Traces corresponding to new sweep values are added to the same graph. Traces corresponding to unmatched sweep values are deleted.

For example, set the variables as shown below.

The graph plotted in this case includes plots for all four sweep values for CAP, as shown below.

For the next simulation run, change the sweep values for CAP to 2.5:4.8:3.6:5.2. Note the change in the values of CAP for which the simulation is run (mismatch values are underlined), as shown below.

Values of CAP in the first run: 1.2, 2.5, 3.0, and 4.8

Values of CAP in the second run: 2.5, 4.8, 3.6, and 5.2

With the Refresh plotting, the traces corresponding to CAP = 2.5 and 4.8 are updated with new simulation data. Traces corresponding to CAP = 1.2 and 2.0 are removed. Traces corresponding to CAP = 3.6 and 5.2 are added.

Unsupported Scenarios of Sweep Variations

In the following scenarios, the graphs for common sweep values for the swept variables are not refreshed:

Performing Quick Plotting

When the ADE Explorer setup includes multiple sweep or corner points, or the transient simulations are time-consuming, plotting output waveforms through the Plot All option could consume significant time and memory. In this case, you can use the Quick Plot option to plot outputs faster and with much lesser memory usage (data size <1 percent of PSF XL). The quick plot is faster because it uses a reduced set of data points as opposed to the Plot All option that generates a full view covering all data points. The quick plot compresses data, and therefore, saves memory.

However, quick plots have lower resolution as compared to the full view that is generated using the Plot All option. When you send the quick plot waveforms to Calculator, the full plot data is loaded so that the calculations are not affected. In addition, if you perform any operations on quick plot signals using Results Browser, such as Diff, the output waveform is also of low resolution.

The quick plot option is available only when the simulation run is complete and the output results are generated. Currently, this option works only for the transient signals and waveform expressions, and is available only for the Detail and Detail-Transpose results views. In addition, quick plot can be generated for all signals and expressions except for histograms. The Quick Plot option is disabled when you re-evaluate the results for expression after the simulation run is complete.

While running a Monte Carlo simulation, quick plotting is not supported if the Save Waveforms (Simulation Data) check box is not selected on the Monte Carlo options form. In this case, an error message is displayed in CIW.

If you perform the quick plotting of scalar signals, the full view plot is generated.

To generate the quick plot for a selected signal or expression:

To generate the quick plot for all the signals and expressions:

The figure below shows the waveforms from normal plot (full view) displayed in red and quick plot displayed in blue for a current signal, /V0/PLUS. The quick plot waveform includes fewer points as compared to the full view. When the full view and quick plot are displayed in the same window in append mode, you can zoom into the plots to compare them and see the differences between them. In addition, notice that the legend of the quick plot is different from the full view, which helps differentiating between the two plots.

The equivalent full data is loaded when you send the quick plot waveform data to Calculator. The loaded waveform is a leaf, for example:

leafValue( IT("/V0/PLUS") "I15.wn" 2 )

In the Results Browser, the signals are displayed in the order they are computed and may not match the order in which they are viewed in the full view data.

The saved quick plot data can be loaded into graph and is located at:

<Interactive>/wavedb/<test>.vqv

You can also generate a full view from the quick plot data. To do this, right-click the quick plot waveform and choose Quick Plot Expand to – New Window/New Subwindow/Current Window.

You can also read the Virtuosity: Can I Speed up My Plots? blog for more information about quick plotting.

Using the Plot Output Commands

To plot the outputs, choose one of the below listed commands in the Results – Plot Outputs menu.

Transient

Plots the transient response for each node

AC

Plots the AC response for each node

DC

Plots the DC sweep response for each node

Noise

Plots the squared noise voltage for each node

Expressions

Plots the waveforms for expressions you define in the Setting Outputs form. For more information, see Saving Output Expression.

Plotting the Current or Restored Results

To plot the most recent results in the graph window:

  1. Choose Outputs – To Be Plotted – Select On Design.
    Nodes and terminals that you have already selected are now highlighted.
  2. In the schematic window, select one or more nodes or terminals.
  3. Press the Escape key when you finish selecting nodes and terminals.
  4. You can also add a signal or expression manually to the outputs setup.
    The terminal type for the added signal or expression is determined by the Terminal Selection Type set in the Plotting/Printing Options form.
    For example, manually add an instance terminal /I0/M3/B to the outputs setup. Depending on the specified Terminal Selection Type, the following four outcomes are possible:
    • Current: Implies that a signal (I) is added.
    • Voltage: Implies that a signal (V) is added.
    • Both: Implies that a signal (I) and signal (V) are added.
    • Prompt: In this case, the following form is displayed, where you can select the type of signal to save.
      On selecting a net, the output Type is set to signal as shown in the figure below.
    When you add new expressions, the Plot check box is selected. On adding new signals, both the Plot and Save check boxes are selected. If an added signal is not found in the schematic design hierarchy then it is considered invalid and gets highlighted in yellow in the outputs setup.
    If an expression is created on a non-existent net or terminal or if the expression contains signals that do not exist in the schematic, the expression is highlighted in yellow in the outputs setup.
  5. Choose a Results – Plot Outputs command in the ADE Explorer window.
    The system plots the results you selected in the current graph window or opens a new graph window if one is not open.

To plot all of the available results at once,

You can plot only saved voltages and currents.

When you choose Outputs – To be Plotted – Select on Design, and then select an iterated instance in the schematic, the Select instTerm IN on iterated inst form is displayed.

If you select a bus signal, the Select bit from bus form is displayed.

These forms enable you to select from one to all bits of an iterated item. When you select the top element in the list box, all the individual bits are selected. You can also select an individual bit with the left mouse button.

Ctrl-Left mouse will toggle selection of an item. Shift-Left mouse will select all items between the last selected item and the current item.

Plotting Parasitic Simulation Results

When you plot the results of a parasitic simulation, only terminals and device pins can be mapped from the schematic to the extracted view.

To select results in the schematic while parasitic simulation is enabled,

  1. In the ADE Explorer window, choose Outputs – To Be Plotted – Select on Design.
  2. In the schematic, select a terminal or pin, or a wire near a terminal or pin.
    If you select a point in the middle of a wire, the system chooses the nearest terminal or device pin and you might not get the right data.
    The system draws an X to mark the point you selected.
  3. Choose a Results – Plot Output command.
    The color of the waveform matches the color of the X.

You cannot probe nets that connect only sources and loads because these nets do not exist on the extracted view. You also cannot probe nets between parasitic components that were removed by selective annotation because these nets were removed when the selected view was built.

Using the Direct Plot Commands

You can plot common waveforms quickly in the ADE Explorer window using the Direct Plot commands. With these commands, you do not need to use the calculator to create common expressions and you do not need to add the nets or terminals to the plot set.

To use Direct Plot,

or,

To use Direct Plot commands,

  1. Choose a command from the Results – Direct Plot menu.
    If necessary for the command, a form appears.
    The graph window opens. If a graph window was already open, it becomes active.
  2. Look in the schematic window for a prompt.
    The prompt tells you what to select in the schematic.
  3. Select the signals necessary for the function and press the Escape key.
    The system plots the signals. The system shuffles windows automatically, so that the graph window is in front.

There are two modes for the Direct Plot commands:

To choose the mode,

  1. Choose Results – Plotting/PrintingPlotting/Printing Options.
    The ADE Explorer Plotting/Printing Options form appears. For more information about the form, see ADE Explorer Plotting/Printing Options Form.
  2. Choose the required options from the Direct Plot group box and click OK.

Using the Direct Plot Main Form

When you choose Results – Direct Plot – Main Form, the following form appears:

For DC

  1. Choose Results – Direct Plot – Main Form. The Direct Plot Form appears.
  2. Select dc in the Analysis section.
    The Direct Plot Form is updated, as shown below:
  3. Specify the Plotting Mode. You can specify:
    • Append to append the new signal to the current graph.
      The Append mode is not recommended for plots with different scales and units for the X axis. It can give strange results because Virtuoso Visualization and Analysis XL opens a new subwindow to plot any data that does not match the units and range of the existing traces.
    • Replace to replace the current graph with the new signal. This is the default option.
    • New SubWin to plot the signal in a new subwindow.
    • New Win to plot the signal in a new window.
  4. The functions that are available are: Voltage, Voltage Ratio, Current, Current Ratio, Power, Power Ratio, Transresistance, and Transconductance. Based on the selected function and available data, the form changes dynamically to display the applicable options.
    Enable Add To Outputs to add expressions for the results to the outputs section and plot in the mode that you selected.
    On deselecting this check box, it turns into a button that can then be clicked to add the expressions for the results to the outputs section. If this check box is reselected, on clicking Replot, the results are plotted as well as added to the outputs section.
    Based on the selected function and available data, the form changes dynamically to display the applicable options.
    • For Voltage, choose the nets and terminals to plot. You can select one of the following options to display the graphs for the selected analysis type.
      • Net: Lets you select nets from the schematic.
      • Terminal: Lets you select instance terminals from the schematic
      • Differential Nets: Lets you select differential nets from the schematic.
      • Instance with 2 Terminals: Lets you select an instance with two terminals in the schematic.
    • For Current, choose the terminals to plot. You can select one of the following options to display the graphs for the selected analysis type.
      • Terminal: Lets you select instance terminals from the schematic.
      • Differential Terminals: Lets you select differential terminals from the schematic.
    • For Power, choose the nets and terminals to plot. You can select one of the following options to display the graphs for the selected analysis type.
      • Terminal: Lets you select instance terminals from the schematic.
      • Terminal and V-Reference Terminal: Lets you select positive and negative instance terminals from the schematic.
      • Instance with 2 Terminals: Lets you select an instance with two terminals from the schematic.
      • Total Power: Plots the total power of the circuit.
      • Instance: Lets you select instances from the schematic.
    • For Transresistance, choose the nets and terminals from the schematic. This function gives you the transresistance of the selected net voltage over the selected device node current. From the Select drop-down list, select one of the following options.
      • Numerator Net and Denominator Terminal: Lets you select the numerator net and the denominator instance terminal from the schematic.
      • +-Numerator Net and Denominator Terminal: Lets you select the differential numerator net and the denominator instance terminal from the schematic.
    • For Voltage Ratio, choose the nets and terminals from the schematic. This function gives you the voltage ratio of two net voltages, or a pair of differential net voltages. From the Select drop-down list, select one of the following options.
      • Numerator Net and Denominator Nets: Lets you select the numerator and the denominator net from the schematic.
      • +-Numerator and +- Denominator Nets: Lets you select pairs of differential numerator nets and denominator nets from the schematic.
    • For Current Ratio, choose the terminals from the schematic. This function gives you the current ratio of two instance terminal currents.
    • For Power Ratio, choose the nets and terminals from the schematic. From the Select drop-down list, select one of the following options.
      • Numerator Net and Denominator Terminals: Lets you select the numerator and the denominator instance terminals from the schematic.
      • +-Numerator and +- Denominator Terminals: Lets you select pairs of differential numerator instance terminals and denominator instance terminals from the schematic.
      • Num. and Denom. Instances with 2 Terminals: Lets you select the numerator and denominator instances with two terminals from the schematic.
    • For Transconductance, choose the nets and terminals from the schematic. This function gives you the transconductance of the selected device node current over the selected device net voltage. From the Select drop-down list, select one of the following options.
      • Numerator Terminal and Denominator Net: Lets you select the numerator instance terminal and the denominator inet from the schematic.
      • Numerator Terminal and +-Denominator Nets: Lets you select the numerator instance terminal and the differential denominator instance terminals from the schematic.

For AC

  1. Choose Results – Direct Plot – Main Form. The Direct Plot Form appears.
  2. Select ac in the Analysis section.
    The Direct Plot Form is updated, as shown below:
  3. Specify the Plotting Mode. You can specify:
    • Append to append the new signal to the current graph.
      The Append mode is not recommended for plots with different scales and units for the X axis. It can give strange results because Virtuoso Visualization and Analysis XL opens a new subwindow to plot any data that does not match the units and range of the existing traces.
    • Replace to replace the current graph with the new signal. This is the default option.
    • New SubWin to plot the signal in a new subwindow.
    • New Win to plot the signal in a new window.
  4. The functions that are available are: Voltage, Current, Current Ratio and GD. Based on the selected function and available data, the form changes dynamically to display the applicable options.
  5. Choose the nets and terminals to plot. You can select Terminal, Net, Differential Nets or Instance with 2 Terminals in the schematic to display the graphs for the selected analysis type.
  6. Choose the appropriate Modifier to specify the data or plot format.
  7. Enable Add To Outputs to add expressions for the results to the outputs section and plot in the mode that you selected.

For Transient Results

  1. Choose Results – Direct Plot – Main Form. The Direct Plot Form appears.
  2. Select tran in the Analysis section.
    The Direct Plot Form is updated, as shown below:
  3. Specify the Plotting Mode. You can specify:
    • Append to append the new signal to the current graph.
    • Replace to replace the current graph with the new signal. This is the default option.
    • New SubWin to plot the signal in a new subwindow.
    • New Win to plot the signal in a new window.
  4. The functions that are available are: Voltage, Current, Power, Noise Measurement, and Transient Noise.
    Based on the selected function and available data, the form changes dynamically to display the applicable options.
    • For the Voltage, Current, and Power functions, choose the net or terminal to plot. These functions are the same as those available in the Direct Plot form For DC analysis.
      The Prepend Waveform from Reference Directory option can be used for appending multiple checkpoint/restart transient waveforms together to enable you to view complete waveforms. Specify the reference results directory(s) in the field. The signal you choose in your direct plot will then be accessed from the reference directory.
    • For the Noise Measurement function, specify the values of the options that appear in the Histogram section in the form.
      See Histogram Plots for Transient Noise Analysis for more information.
    • For the Transient Noise function, specify the values of the following additional options that appear in the form and choose the net or instance to plot.
      The PSD function generates a PSD waveform for the specified net or instance, and the PN function generates a waveform of the transient phase noise for the specified net or instance.
      Field Description 
      PSD
      		 
      From

      Starting time for the spectral analysis interval.

      		 
      To

      Ending time for the spectral analysis interval.

      		 
      Number of Samples

      Number of time domain points to be used.

      		 
      Window Type

      Window you want to use. If you select Kaiser, type in a value for the Kaiser smoothing factor. The smoothing factor must be in the range 0 <= factor <= 15, where 0 is the same as using a rectangular window.

      Valid values: Blackman, Cosine2, Cosine4, ExtCosBell, HalfCycleSine, HalfCycleSine3, HalfCycleSine6, Hamming, Hanning, Kaiser, Parzen, Rectangular, and Triangular

      Default value: Hanning

      		 
      Smoothing Factor

      Controls the output accuracy. This argument applies only to the Kaiser window type. It is applicable to the Kaiser window only. The Smoothing Factor accepts values from 0 to 15. The value 0 implies no smoothing and is equivalent to a rectangular window.

      Default value: 1

      		 
      Window Size

      Number of frequency domain points to use in the Fourier analysis. A larger window size results in an expectation operation over fewer samples, which leads to larger variations in the power spectral density. A small window size can smear out sharp steps in the power spectral density that might be present.

      Default value: 256

      		 
      Detrending Mode

      Specifies the trend mode. The psd function works by applying a moving windowed FFT to time-series data. If there is a deterministic trend to the underlying data, you may want to remove the trend before performing the spectral analysis. For example, consider analyzing phase noise in a VCO model. Without the noise, the phase increases more or less linearly with time, so it is appropriate to set the detrending mode to Linear. To subtract an average value, set the detrending mode to Mean. Where the spectrum of raw data is desired, set the detrending mode to None.

      Valid values: None, Mean, and Linear

      Default value: None

      		 
      Coherent Gain

      The coherent gain of a window is the zero frequency gain (or the DC gain) of the window. It is calculated by normalizing the maximum amplitude of the window to one and then summing the values of the window amplitudes over the duration of the window. The result is then divided by the length of the window (that is, the number of samples). When you do a dft, the applied Window Type (aside from the rectangular type) changes the signal amplitude. Applying a coherent gain factor is a way to get consistent results regardless of the window type.

      Valid Values: (none), (default), (magnitude), (dB20), and (dB10)

      Default value: (default)

      		 
      Coherent Gain Factor

      This is the scaling factor. A non-zero value that scales the power spectral density by 1/(Coherent Gain).

      Valid values: 0 < coherent_gain_factor < 1. You can use 1 if you do not want this scaling factor to be used.

      Default value: 0

      		 
      PN
      		 
      From

      Starting time for the spectral analysis interval.

      		 
      To

      Ending time for the spectral analysis interval.

      		 
      Cross Type

      Points at which the curves of the waveform intersect with the threshold. While intersecting, the curve may be either rising (rising) or falling (falling). The default value is rising.

      		 
      Threshold

      Threshold value against which the phase noise is to be calculated.

      A threshold tolerance of 0.1*stddev(signal) is used when detecting crossings.
      		 
      Tnom

      Nominal time period of the input waveform.

      If left empty, the pn function takes the value of this field to be nil automatically.

      Default value: nil

      		 
      Window Type

      Window you want to use.

      Valid values: Blackman, Cosine2, Cosine4, ExtCosBell, HalfCycleSine, HalfCycleSine3, HalfCycleSine6, Hamming, Hanning, Kaiser, Parzen, Rectangular, and Triangular

      Default value: Rectangular

      		 
      Smoothing Factor

      Smoothing factor applicable to only Kaiser window. The Smoothing Factor field accepts values from 0 to 15. The value 0 implies no smoothing and is equivalent to a rectangular window.

      Default value: 1

      		 
      Window Size

      Number of frequency domain points to be used while calculating the power spectral density. A larger window size results in an expected operation over fewer samples, which can result in larger variations in the phase noise. A small window size can smear out sharp steps in the phase noise that might be present.

      Default value: 256

      		 
      Detrending Mode

      Determines the expected trend for the underlying data while calculating the power spectral density.

      Default value: None

      		 
      Coherent Gain

      The coherent gain of a window is the zero frequency gain (or the DC gain) of the window. It is calculated by normalizing the maximum amplitude of the window to one and then summing the values of the window amplitudes over the duration of the window. The result is then divided by the length of the window (that is, the number of samples). When you do a dft, the applied Window Type (aside from the rectangular type) changes the signal amplitude. Applying a coherent gain factor is a way to get consistent results regardless of the window type.

      Valid Values: (none), (default), (magnitude), (dB20), and (dB10)

      Default value: (default)

      		 
      Coherent Gain Factor

      This is the scaling factor. A non-zero value that scales the power spectral density by 1/(Coherent Gain).

      Valid values: 0 < coherent_gain_factor < 1. You can use 1 if you do not want this scaling factor to be used. Default value: 0

      		 
      Method Type

      Determines the algorithm you want to use to calculate the phase noise.

      Valid values: Absolute Jitter Method or Direct Power Spectral Density Method.

      Default value: Absolute Jitter Method.

      When the method type is selected as Direct Power Spectral Density Method, ensure that a valid nominal time period value is specified in the Tnom field, otherwise, an error message is displayed.

      Coherent GainFor more information about the options required to plot these waveforms, see the section PSD or PN in the Virtuoso Visualization and Analysis XL User Guide.

    If no data is available for the selected function, a corresponding message is displayed in the form.

For Noise Results

Noise figure is calculated by Spectre if a port is selected as the input source for noise analysis. If a port is not selected as the input, noise figure data is not available.

To plot the noise figure,

  1. Choose Results – Direct Plot – Main Form. The Direct Plot Form appears.
  2. Select noise in the Analysis section.
    The Direct Plot Form is updated, as shown below:
  3. Specify the Plotting Mode. You can specify:
    • Append to append the new signal to the current graph. This is the default option.
    • Replace to replace the current graph with the new signal.
    • New SubWin to plot the signal in a new subwindow.
    • New Win to plot the signal in a new window.
  4. Select the noise parameter function that you want to plot from the Function group box. Based on the selected function and available data, the form changes dynamically to display the applicable options.
  5. Select the Signal Level that you want to plot. By default, ADE Explorer plots the VN2 signal in the Virtuoso Visualization & Analysis XL window. You can plot the VN signal by selecting the V / sqrt(Hz) radio button from the Direct Plot form.
  6. Choose the appropriate Modifier to specify the data or plot format. Magnitude radio button (the default setting) plots the magnitude of the selected signal and the dB20 radio button plots the magnitude in dB.
  7. Select Add To Outputs check box to add expressions for the results to the outputs section and plot in the mode that you selected.
  8. Click Plot to view the results in the Virtuoso Visualization & Analysis XL window.
  9. Click OK.
The mathematical noise-figure expression is where:

VN2 =

The noise voltage

Vin =

The voltage at the input node

Vout =

The voltage at the output node

R =

The source resistor value

C =

1.61e-20 ≅ 4kTΔf

with

T =

291.5K and Δf = 1

For Noise Separation

In addition to the total output noise, individual noise contributions can be plotted if Noise Separation is enabled in the Choosing Analyses form for Noise Analysis.

To plot the noise separation results,

  1. Choose Results – Direct Plot – Main Form. The Direct Plot Form appears.
  2. Select noise separation in the Analysis section.
    The Direct Plot Form is updated, as shown below:
  3. Specify the Plotting Mode. You can select one of the following modes:
    • Append — Select this to append the new signal to the current graph. This is selected by default.
    • Replace — Select this to replace the current graph with the new signal.
    • New SubWin — Select this to plot the signal in a new subwindow.
    • New Win — Select this to plot the signal in a new window.
  4. In the Function section, select the noise separation function that you want to plot. You can select one of the following functions:
    • Instance Output — Plots the noise contribution of the instances.
    • Instance Source — Plots the noise sources of the instances.
    • Source Output — Plots the noise contribution of the primary noise sources.
    • Primary Source — Plots the primary noise sources.
    • Src. Transfer Func — Plots the square of the transfer function square of the primary noise sources.

    Based on the selected function and available data, the form changes dynamically to display the applicable options.
  5. Based on the selected function, the signal level is also detected automatically.
  6. Choose the appropriate modifier to specify the data or plot format. Power (the default setting) plots the power of the selected signal. dB10 plots the magnitude in dB.
  7. In the Filter section, choose filtering details.
    The Include All Types option should be selected. But, if you just want the noise from specific types of noise generators, you can select them from the list box. Also, specify the instances to be included or excluded particular in your summary.
  8. In the Truncate section, choose truncation details to shorten your summary.
    You can shorten your summary by specifying how many of the highest contributors to include in the summary.
  9. Select the Add To Outputs check box to add expressions for the results to the outputs section and plot in the mode that you selected.
  10. Click Plot to view the results in the Virtuoso Visualization & Analysis XL window.
  11. Click OK to close the form.

For Stability Results

  1. Choose Results – Direct Plot – Main Form. The Direct Plot Form appears.
  2. Select stb in the Analysis section.
    The Direct Plot Form is updated, as shown below:
    .
  3. Specify the Plotting Mode. You can specify:
    • Append to append the new signal to the current graph.
    • Replace to replace the current graph with the new signal. This is the default option.
    • New SubWin to plot the signal in a new subwindow.
    • New Win to plot the signal in a new window.
  4. The functions that are available are: Loop Gain, Stability Summary, Phase Margin, Gain Margin, PM Frequency and GM Frequency. Based on the selected function and available data, the form changes dynamically to display the applicable options.
    1. When you select Loop Gain, the form re-displays to show the Modifier section.The loop gain output is a complex waveform and you can select it to plot Magnitude, Phase or both (Magnitude and Phase). Whenever you choose to plot Magnitude, the Magnitude Modifier section appears on the form. You can select None, dB10 or dB20, as needed. Whenever you plot both the magnitude and phase, the graph window changes to the strip mode. It reverts back to the composite mode for other plot operations.
      There is a difference between the ADE Explorer and Spectre definition of loop gain. For the feedback circuit shown below:
      The closed loop gain is defined as:


      The Spectre output defines loop gain as the product AF, while others (like the ADE Explorer Calculator phaseMargin and gainMargin functions) define -AF as the loopGain. Therefore, to obtain the same results from ADE Explorer, you need to negate the Spectre’s loopGain as illustrated below:
      gainMargin( -1 * getData( "loopGain" ?result “stb” ), 1) phaseMargin( -1 * getData( "loopGain" ?result “stb” ) )
    2. Phase Margin, Gain Margin, PM Frequency and GM Frequency constitute the margin data. This information is calculated from the loop gain data for the circuit. The information is only available when frequency is swept in the stability analysis and the swept range is sufficient to calculate the values. When the selected margin data is scalar the values are displayed on the form itself.
      When the swept frequency range is not sufficient to calculate the selected margin data an error is reported in the Direct Plot Form and the Plot and Add to Outputs button are not available.
      When frequency is not swept in the stability analysis and you choose any of the margin data functions an error is reported in the Direct Plot Form and the Plot and Add to Outputs button are not available.
    3. Selecting Stability Summary displays all the margin data collectively on the form, when the data is scalar. You do not have the facility to plot or add the four outputs when this function is chosen. Use the individual margin data function for this operation.
      When frequency was not swept or the margin data is not scalar an appropriate error is reported in the Direct Plot Form and the Plot and Add to Outputs button are not available.
  5. Enable Add To Outputs and plot in the mode that you selected.
    This option makes no checks for duplication in outputs.

All other parts of the Direct Plot form work the same way as they do for other analyses. Refer to the Spectre Circuit Simulator RF Analysis User Guide for details.

This form handles parametric (family) data. The Loop Gain would be a set of curves for family data. Similarly for non-parametric data, Phase Margin and Gain Margin will be scalars. A horizontal straight line will be plotted for them.

For Pole Zero Results

Once you run a simulation for Pole Zero analysis, you can use the Direct Plot main form to view the poles and zeros plotted on the real/imaginary plane.

  1. To open the Direct Plot Form, select Results – Direct Plot – Main Form.
  2. Select pz in the Analysis section.
    The Direct Plot Form is updated to display the applicable functions and options:
  3. Select the option, Poles if you want to plot only poles, Zeros if you want to plot only zeros and Poles and Zeros if you want to plot both poles and zeros.
    By default, the option Poles and Zeros is selected.
  4. Set the required options in the Filter Out section and click OK. This section provides a combination of filtering mechanisms that you can select in order to plot the poles and zeros. These are:
    • Max Frequency: This option enables you to filter out poles and zeros that are outside the frequency band of interest (FBOI) and that do not influence the transfer function in the FBOI. The default value is that specified in the fmax field in the Pole-Zero Options form. Only poles and zeros whose magnitudes exceed the frequency value specified are filtered out.
    • Real Value: This option enables you to specify the real part of the frequency. Only poles and zeros whose real values are less than or equal to the real value specified are filtered out.
      By default, no filtering is selected. You can set the filtering criteria once you specify either poles or zeros or both to be plotted.
  5. Enable Add To Outputs to add expressions for the results to the Outputs Setup and plot in the mode that you selected.
  6. Click Plot to view the results in the Graph Window:

Poles and zeros are plotted in scatter mode. This implies that poles and zeros are plotted individually but not connected. Poles are represented by the symbol x and zeros by the symbol o. The complex data is plotted with poles and zeros.

Non-Swept Parameters

For the non-swept case, the result of Pole Zero analysis will be two waveform objects, one representing poles and another representing the zeros. The two wave objects are plotted in the same color however, poles will be represented by the symbol x and zeros by the symbol o.

Swept Parameters

For swept parameter Pole Zero Analysis, it is possible to create the root-locus plot. Instead, the poles and zeros are plotted corresponding to each Swept Parameter value.

For Transfer Function

To plot the transfer function,

  1. Choose Results – Direct Plot – Main Form. The Direct Plot Form appears.
  2. Select xf in the Analysis section.
    The Direct Plot Form is updated, as shown below:
  3. Specify the Plotting Mode. You can specify:
    • Append to append the new signal to the current graph.
    • Replace to replace the current graph with the new signal. This is the default option.
    • New SubWin to plot the signal in a new subwindow.
    • New Win to plot the signal in a new window.
  4. Choose either Voltage Gain or Transimpedance if you selected output voltage for the transfer analysis, or Current Gain or Transconductance if you selected output current for the transfer analysis.
  5. Specify the modifiers as needed.
  6. Select either the instance or instance terminal in the schematic.
    The graph window redisplays, showing the new plot.

To replot with modifications, make changes to the specifications on the XF Results form and click Replot.

For S-Parameter

A typical S-parameter direct plot shows a parameter function plotted against frequency, based on a pair of psin elements that define an input and an output circuit port.

You define S-parameter direct plots with the S-Parameter Results form. If the form does not offer a plot you want to generate (for example, plots of complex computed results), use the waveform calculator.

By default, the plots appear in the current Virtuoso Analog Design Environment graph window or subwindow. The current subwindow has a rectangle around its window number (in the upper-right corner). To use a different subwindow, select it before beginning the direct plot procedure. If no graph window or subwindow is open, this plot function automatically opens one.

  1. To plot the results, choose Results – Direct Plot – Main Form.
    This command automatically opens a graph window (unless one is already open), the design schematic (unless it is already open), and the Direct Plot Form.
  2. Select sp in the analysis section.
    The Direct Plot Form is updated, as shown below:

For detailed information about the form, see S-Parameter Results.

To plot S-parameter results,

  1. Specify the Plotting Mode. You can specify:
    • Append to append the new signal to the current graph.
    • Replace to replace the current graph with the new signal. This is the default option.
    • New SubWin to plot the signal in a new subwindow.
    • New Win to plot the signal in a new window.
  2. Click the radio button for the S-parameter or noise-parameter function you want to plot.
    A brief description of the function appears below the buttons, and the bottom of the form changes to show options for the function.
    Some functions are defined only for two-port circuits. If you choose a function that is not available for your circuit data set, a warning message appears at the bottom of the form. Click a button on the figure for information about a function. If you need an equation that is not represented on the form, use the calculator to build, evaluate, and plot it.
  3. Choose the appropriate Plot Type and Modifier to specify the plot type and the data or plot format.
  4. Specify and draw the plot.
    For S, Z, Y, or H parameters (shown as SP, ZP, YP, and HP on the form), generate plots for ports 1 through 3 by clicking the appropriate parameter button at the bottom of the form. To generate plots for any higher-numbered ports, use the cyclic fields beside the buttons to specify the output and incident ports. Then click the S, Y, Z, or H button that is next to the cyclic field to plot.
For circuits with three or fewer ports, the form has no cyclic fields.

S-Parameter Probing

Select sp sprobe port in the Analysis group box of the Direct Plot form.

The following fields are displayed.

  1. From the Select Sprobe drop-down list, select an sprobe.
  2. From the Select Port Direction drop-down list, select one of the following options.
    • Left: uses the left port of the selected sprobe, specified through the Choosing Analyses form for sp analysis.
    • Right: uses the right port of the selected sprobe, specified through the Choosing Analyses form for sp analysis.
  3. Select a function from the Function group box.
  4. Select a plot type from the Plot Type group box.
  5. Select a modifier from the Modifier group box.
  6. Click Plot to plot the wave.

For Loop Finder

To highlight the nets within a loop,

  1. Choose Results – Direct Plot – Main Form. The Direct Plot Form appears.
  2. Select lf in the Analysis section.
    The Direct Plot Form is updated, as shown below:
  3. Choose a loop from the loops table. The circuit nodes (nets) within the selected loop are displayed in the nets table, along with their impedance value. If you want all the nets within a particular loop to be highlighted, double click the loop.
  4. In the Loops Sort By field, you can specify a sorting criteria for the loops displayed in the loops table. You can sort the loops by frequency or damping factor, in ascending or descending order.
  5. In the Select Nets From (Ohm) and To fields, specify the minimum and maximum impedance for the nets to be displayed. All the nets with an impedance lying outside the specified range are excluded from the nets table.
    If only the minimum impedance is specified in the Select Nets From (Ohm) field, all the nets with an impedance greater than the specified impedance are displayed. And, if only the maximum impedance is specified in the To field, all the nets with an impedance lower than the specified impedance are displayed.
  6. Choose the nets to be highlighted from the nets list box. To select multiple nets, press the Ctrl key and select the nets, or (for contiguous selection) press the Shift key and select the nets.
  7. Click Highlight. The selected nets are highlighted in the schematic, in red, as shown below:
  8. Click OK to close the form.

Printing Results

To print text results and reports to the Results Display Window, do the following:

For guidance on using the Results Display Window to perform tasks, see the following sections.

Printing Results

To print the results in the Results Display Window either in hardcopy or to a file,

  1. Choose Window – Print.
    The Print form appears.
  2. Choose the correct window number from the Print from window cyclic field.
    This is the window containing the contents you want to print.
  3. Type a value in the Number of Characters Per Line field.
  4. Choose either the Printer or File radio button in the Print To field.
    You must type a filename if you choose File.
  5. Click OK.

Saving State from the Results Display Window

You can use Save State and Load State capability to save the current setup of display options for printing waveforms such as printing format, setting a printing range if the amount of data is too large, printing at a certain interval, and changing the order of the display. You can save the state of the window into a file. Later if you run another simulation and do Load State, the new data can be loaded back and displayed as you specified when you saved the state. Save State and Load State are applicable only to waveforms (that is, expressions that can evaluate to a waveform). If you print a single number, like a node voltage, these commands are disabled. You get a message stating this value is not a waveform and cannot be loaded back.

To save the contents and format of a Results Display Window,

  1. Choose Window – Save State.
    The Save Window form appears.
  2. Type a filename in the field.
  3. Click OK.

Loading State in the Results Display Window

To load a window state that you previously saved,

  1. Choose Window – Load State.
    The Load Window form appears.
  2. Type the name of the saved file in the field.
  3. Click OK.

Updating Results in the Results Display Window

To update the Results Display Window with results from a new simulation,

This updates the data using the current window setup. Update Results is applicable only to waveforms (that is, expressions that can evaluate to waveforms). If you print a single number, like a node voltage, this command is disabled.

Making a Window Active

There is no limit to the number of Results Display Windows you can have open, but only one window is active at a time. All printouts go to the active window.

To make a window active,

Editing Expressions

You can edit any expressions that evaluate to waveforms (for example, DC operating parameters, model parameters, and transient operating parameters). If you print only one value, the edit menu choices are not available. The editing commands operate on only the last table in the active Results Display Window.

To edit expressions in the print window,

  1. Choose Expressions – Edit.
    The Edit window appears.
  2. Edit the expressions using the form buttons and fields.
You should convert both numbers to the same type (that is, integer or float) before you compare them. For more information, see Integer versus Floating-Point Division in the Arithmetic and Logical Expressions chapter of the Cadence SKILL Language User Guide.

Setting Display Options

To change the display options,

  1. Choose Expressions – Display Options.
    The Display Options form appears.
  2. Type the values into the form and select a format.
If the Results Display Window contains more than one type of results, the Display Options commands apply only to the last result (if the last result can evaluate to a waveform). After the data is edited, only the last result appears in the window. If you want to preserve the previous results, you can open a new Results Display Window and print the results to be edited in the new window.

Displaying Output Information

To display output information, choose Info – Show Output.

Output names are truncated to fit into columns if they are too long. The Show Output command shows the output names in full.

Specifying Results to Print

Before you can print results, you need to specify which results to print.

  1. Do one of the following:
    • Run a simulation.
    • In the ADE Explorer window, choose Results – Select, choose the desired data file, and click OK.
  2. Make sure the Schematic window for the selected design is open.

To print results for the current simulation or for a selected data file,

  1. Choose a print command from the Results menu.
  2. Select a node in the Schematic window.
    The Results Display Window shows
    • The command syntax for the print option you selected
    • The results for the instance you selected

    Each time you click a node in the Schematic window, information about the node is added to the Results Display Window.

Printing Components

Refer to the below topics:

Printing DC Operating Points

To print the DC operating points of the components in your circuit,

  1. Choose Results – Print – DC Operating Points.
  2. Move your cursor into the Schematic window.
    The CIW prompts you to select instances for the operating point output.
  3. Click an instance.

If the selected instance is a textual subcircuit, operating points for all devices in the subcircuit will be printed. It may take some time to search for all instances in a textual subcircuit. To disable the feature, set the following environment variable in your .cdsenv:

asimenv.printing  printInlines  boolean  nil

Printing Transient Operating Points

To print the final transient operating points of the nodes or components in your circuit,

  1. Choose Results – Print – Transient Operating Points.
  2. Move your cursor into the Schematic window.
    The CIW prompts you to select instances for the transient operating point (OPT) output.
  3. Click an instance or node.

If the selected instance is a textual subcircuit, operating points for all devices in the subcircuit will be printed. It may take some time to search for all the instances in a textual subcircuit.To disable the feature, set the following environment variable in your .cdsenv:

asimenv.printing  printInlines  boolean  nil

Printing Model Parameters of Components

To print the model parameters of the nodes or components in your circuit,

  1. Choose Results – Print – Model Parameters.
  2. Move your cursor into the Schematic window.
    The CIW prompts you to select instances for the model parameter output.
  3. Click an instance of a device.

If the selected instance is a textual subcircuit, model parameter for all devices in the subcircuit will be printed. It may take some time to search for all instance in a textual subcircuit. To disable the feature, set the following environment variable in your .cdsenv:

asimenv.printing  printInlines  boolean  nil

Printing Noise Parameters of Nodes or Components

To print the noise parameters of the nodes or components in your circuit,

  1. Choose Results – Print – Noise Parameters.
    The Select Frequency Value form appears.
    If the form does not appear, press F3.
  2. In the Frequency field, type the frequency value at which you want the noise parameters to print.
    The default frequency is 1K.
  3. Move your cursor into the schematic window.
    The CIW prompts you to select instances for the VNP output.
  4. Click an instance or node.

Noise Summary

To display the noise contribution of the components in a circuit,

  1. Run a noise analysis simulation.
  2. Choose Results – Print – Noise Summary.
    Alternatively, right-click any cell in the Test or Output column of the Results tab and choose Print – Noise Summary.
    The Noise Summary form is displayed.
  3. Choose one of the following noise summary types:
  4. In the FILTER group box, do the following:
    1. From the hierarchy level drop-down list, specify the hierarchy levels up to which you want to view the noise contribution results in the Results Display Window.
    2. Specify the options to include or exclude device types or instances. Refer to the section Specifying Device Types and Instances to Include or Exclude below.
  5. If you choose integrated noise, you have the option of using a weighting factor.
    The flat weighting factor specifies that the integration be performed on the original unweighted waveform.
    The from weight file selection specifies that, before the integration is performed, the noise contributions of particular frequencies in the original waveform be weighted by factors supplied from an input file. The weighting file must have one of the following entries on the first line: db, mag, dbl, DB, MAG, DBL. Each additional line must contain a pair of X and Y values. All the pairs together must define a function. For example:
    mag
1          .001641
60         .001641
100        .007499
200        .05559
  6. Choose filtering details to include or exclude particular instances in your summary.
  7. If needed, choose truncation details to shorten your summary. In the TRUNCATE & SORT group box, specify options to truncate and sort your noise summary data.
  8. From the PARAMETRIC VARIABLES list, select a value of the design variable.
    This list is displayed only for parametric dataset. It is recommended that you select the leaf dataset that you want to view the output for to launch the Noise Summary form.
  9. Select the Write RCNet check box to print the information about parasitic resistors and their values for each physical wire net in the noise summary results. This provides users the information to diagnose the noise contribution issues related to abnormal wire nets.
    This option is available only when,
    • Spectre X is selected as the simulation performance mode and Preset is set to MX in the High-Performance Simulation Options form.
    • The following statements are set in Spectre: rcr_net_wire_noise = yes and rcr_net_res_info = yes.
  10. Click OK.
    The Results Display window is displayed.
    Set the maestro.gui showNoiseSummaryinTableWidget environment variable to t in the .cdsinit file to see the Noise Summary window instead of the Results Display window. The Noise Summary window displays corner-specific noise summary report in tabulated format.
    You can shorten your summary by specifying the number of highest contributors to be included in the report, by specifying the percentage of noise a device must contribute to be included in the summary, or by specifying the level of noise a device must contribute to be included in the summary.
    The precision of the noise data displayed in the Noise Summary window can be controlled using the environment variable asimenv.noiseSummary digits. The default value for this variable is 6 and can be set to any other integer value.
    For example, the following command sets the value of the variable to 10:
    envSetVal("asimenv.noiseSummary" "digits" 'int 10)
    The number of decimals printed for any relative contribution is controlled using the environment variable asimenv.noiseSummary percentDecimals. The default value for this variable is 2 and can be set to any other integer value.
    For example, the following command sets the value of the variable to 4:
    envSetVal("asimenv.noiseSummary" "percentDecimals" 'int 4)

Noise Summary Window

The Noise Summary window displays the noise summary report and has separate tabs for each corner.

This window is displayed only when the variable maestro.gui showNoiseSummaryinTableWidget is set to t.

Each tab displays information for the following fields:

Field Description

Parameters for Corner

Displays the semicolon-separated list of parameters for a corner.

Select Parametric Sweep Values

Lets you select the parametric sweep values for which the results are to be displayed in the Noise Summary table.

According to the selected value, the information displayed in the text field below this drop-down list changes.

This text field displays the following information:

  • The noise summary type along with the sorting method
  • Points for which the noise data is calculated
  • Total summarized noise
  • Total input referred noise
  • Total shot noise

Noise Summary table

Displays the noise summary results as customized through the Noise Summary form.

This table has the following columns:

  • Device: Specifies the name of the device.
  • Param: Specifies the name of the parameter.
  • Category: Specifies the noise category.
    To see this column, set the SHELL variable SPECTRE_NOISETYPE=1.
  • Noise Contribution: Displays the noise contribution for the given device.
  • % Of Total: Displays the percentage of noise that the given device has contributed to the total summarized noise.

Related Topics

maestro.gui showNoiseSummaryinTableWidget

Specifying Device Types and Instances to Include or Exclude

Device types in your design appear in the list box in the FILTER group box.

To specify which device types to include and which to exclude from the noise summary, do the following:

  1. To include all device types in the summary, click All Types.
  2. (Optional) To exclude individual device types, hold down the Ctrl key and click each one.

Alternatively, you can do the following:

  1. To exclude all device types from the summary, click None.
  2. Select each device type you want to include in the summary:
    • You can hold down the Shift key to select more than one contiguous device type.
    • You can hold down the Ctrl key to select more than one noncontiguous device type.

To specify instances to include in the noise summary, do the following:

  1. To the right of the include instances field, click Select.
  2. In the schematic window, select one or more instances.
    Each instance path appears in the include instances field.
  3. Press Esc when you are finished selecting.

Alternatively, in the include instances field, you can type the instance names for which you want to filter the noise contribution results. For example, if you want to view the noise contribution only for the /I0/C0 instance, type /I0/C0.

You can also use the wildcard character * to filter the results. For example, if you want to view the noise contribution for all the instances under I0, type /I0/* in the include instances field. The Results Display window shows the results for all the instances under I0 up to the specified hierarchy levels, as shown in the following figure.

To specify instances to exclude from the noise summary, do the following:

  1. To the right of the exclude instances field, click Select.
  2. In the schematic window, select one or more instances.
    Each instance path appears in the exclude instances field.
  3. Press Esc when you are finished selecting.

Truncating Noise Summary Data

From the TRUNCATE & SORT group box on the Noise Summary form, you can select a truncation option to limit the number of noise contributors that appear in the Results Display window when you click Apply or OK.

To specify no truncation of noise data, do the following:

To limit the number of noise contributors that appear in the summary, do the following:

  1. Select by number.
  2. In the top field, type the number of highest noise contributors you want to see.
    The program reports only that number of noise contributors.

To limit the report to only those devices that contribute a certain percentage of the total noise, do the following:

  1. Select by rel. threshold.
  2. In the noise % field, type the minimum percentage noise contribution threshold.
    The program reports only those devices that contribute at least the minimum percentage of the total noise.

To limit the report to only those devices that contribute a minimum level of noise, do the following:

  1. Select by abs. threshold.
  2. In the noise value field, type the minimum noise contribution threshold.
    The program reports only those devices that contribute at least the minimum noise value.

Sorting Noise Summary Data

From the TRUNCATE & SORT group box on the Noise Summary form, you can sort the list of devices that the program reports by noise contributors (highest to lowest), composite noise (highest to lowest), or device name (alphabetical from A to Z). The report appears in the Results Display window when you click Apply or OK.

To request one or more sorted lists of noise contributors in your noise summary report, do the following:

You can select one, two, or three check boxes. The number of boxes you select determines the number of lists that appear in your Results Display Window when you click Apply or OK.

Specifying the options to customize the printed Noise Summary data

The OPTIONS group provides the following options to customize the way noise summary is printed:

Controlling Precision of Printed Noise Data

You can control the precision of the noise data that you print by setting the following variable in your .cdsenv file:

asimenv.noiseSummary digits int numberOfDigits

where numberOfDigits is the number of digits to print.

For example, to specify ten digits of precision, use the following setting:

asimenv.noiseSummary digits int 10

The default value for this variable is 6.

Alternatively, you can set this value for the current session using the following command in your CIW:

envSetVal("asimenv.noiseSummary" "digits" ’int 10)

You can specify the number of digits to use when printing relative noise contributions by setting the following variable in your .cdsenv file:

asimenv.noiseSummary percentDecimals int numberOfDigits

where numberOfDigits is the number of digits to print.

For example, to specify four digits for relative contributions, use the following setting:

asimenv.noiseSummary percentDecimals int 4

The default value for this variable is 2.

Alternatively, you can set this value for the current session using the following command in your CIW:

envSetVal("asimenv.noiseSummary" "percentDecimals" ’int 4)

You can control the precision of your printed results using the aelPushSignifDigits SKILL function as follows:

aelPushSignifDigits(numDigits)

where numDigits is the number of digits of precision you want.

Example

aelPushSignifDigits(4)
rn             37.9322e-18    fn             0              total
37.9322e-18
aelPushSignifDigits(8)
rn             37.932238e-18  fn             0              total 
37.932238e-18

Printing DC Mismatch Summary

To print the DC Mismatch summary in your circuit,

  1. Choose Results – Print – Mismatch Summary.
    This menu option is enabled when ever analysis is included in the last run or the results directory specifically selected through ADE Explorer, contains the results for analysis.
    The DC Mismatch Summary form appears
  2. Specify a value in the Print results when value is field.
  3. Specify the type of devices you need to print the results for, in the Filter section. The Include all types and Include none buttons can be used to include or exclude all types at a single click. You can include specific instances or exclude specific instances. You can either type the instance names or use the select buttons to pick them from schematics. The Clear button is used to clear the fields.
  4. Specify the information to be made available for the various device types, in the Variations to Print section. The Include all columns and Include none buttons can be used for easier list box operation.
  5. Truncate and sort data by top contributors and relative/absolute contribution. The default is relative contribution with the threshold being the value of the threshold parameter used on the analysis line. You can sort by variation or device name.

Printing AC Match Summary

To print the AC match summary in your circuit,

The Results Display Window displays the acmatch analysis run summary using the criteria you specified.

Printing Stability Summary

To print the stability summary in your circuit,

  1. Choose Results – Print – Stability Summary. The Stability Summary form appears.The form enables you to print Phase Margin, Gain Margin or Both.
    This menu option will be enabled only when stability analysis was included in the last run or the results file exists in the results directory when you specifically selected an existing results directory through ADE Explorer.
    The form handles parametric (family) data and prints results at all available sweep points.
  2. Choose the required data and click OK.
    The Results Display Window displays the stability summary using the criteria that you specified. For example, if you had swept temperature and capacitor values with the parametric tool for the stability analysis and selected the Both option on the form, the Results Display Window will appear as follows:

Printing Pole Zero Summary

To print the Pole Zero summary in your circuit,

  1. Choose Results – Print – Pole Zero Summary. The Pole-Zero Summary form appears. The form enables you to print poles or zeros, or poles and zeros with filtering options.
    This menu option will be enabled only when pole zero analysis was included in the last run or the results file exists in the results directory when you specifically selected an existing results directory through ADE Explorer.
  2. Select the option, Poles if you want to plot only poles, Zeros if you want to plot only zeros and Poles and Zeros if you want to plot both poles and zeros.
    By default, the option Poles and Zeros is selected.
  3. Set the required options in the Filter Out section and click OK. This section provides a combination of filtering mechanisms that you can select in order to plot the poles and zeros. These are:
    • Max Frequency: This option enables you to filter out poles and zeros that are outside the frequency band of interest (FBOI) and that do not influence the transfer function in the FBOI. The default value is that specified in the fmax field in the Pole-Zero Options form. Note, that for the Direct Plot form, fmax is read from the header of the psf data. Only poles and zeros whose magnitudes exceed the frequency value specified are filtered out.
    • Real Value: This option enables you to specify the real part of the frequency. Only poles and zeros whose real values are less than or equal to the real value specified are filtered out.
      By default, no filtering is selected. You can set the filtering criteria once you specify either poles or zeros or both to be plotted.
  4. The Results Display Window displays the pole zero summary using the criteria that you specified:

Printing DC Node Voltages

To print the DC node voltages of the nodes or components in your circuit,

  1. Choose Results – Print – DC Node Voltages.
  2. Move your cursor into the Schematic window.
    You are prompted to select nets for the VDC output.
  3. Click a node.

Printing Transient Voltages

To print the transient node voltages of the nodes in your circuit,

  1. Choose Results – Print – Transient Node Voltages.
    The Schematic window comes into the view and the Select Time Value form appears.
  2. In the Time field, type the time value at which you want to print the transient node voltages. The default time value is 0.
  3. Select nets, for which you want to view the voltage value, on the schematic.
    For each selected net, the voltage value is displayed in the Results Display Window.
  4. Press <Esc> after the selection is complete.

Printing Sensitivities

To print the sensitivities in your circuit,

  1. Choose Results – Print – Sensitivities.
  2. Move your cursor into the Schematic window.
    You are prompted to select nets for the output.
  3. Click a net or port.

Printing Capacitance Data

When you run a transient or dc analysis with the captab option selected in the analysis option.

To view capacitance data:

  1. Choose Results - Print - Capacitance Table.
    If you had opted to save captab data for more than one analysis, the Choose CapTab Info Result form appears first.
    Select one captab result file from the Choose Result cyclic box and click OK.
    The Capacitance Table appears as shown below:
    The table shows captab data in five columns:
    • From: The nodes from which capacitance is measured.
    • To: The nodes to which capacitance is measured.
    • Variable: Variable capacitance between nodes.
    • Fixed: Fixed capacitance between nodes.
    • Total: Total capacitance between nodes.
  2. Select one of more sweep values for which the capacitance table is to be printed by using the cyclic buttons in the Select sweep value group box. The values in the Capacitance Table change dynamically as you select the different options.
  3. Click the Print button to save or print captab data.
    The Print form appears.
  4. Specify values in this form as follows:
    1. Number of characters per Line: Number of characters to be printed on a line.
    2. Column Width: Width of the columns to be printed. The default value is 14.
    3. Column Separator: Column separator to be used for printing the table. The default is a space.
    4. Print To: If you want to print to a printer, select the Printer option button and specify a command. If you want to print to a file, select the File option button and specify a filename.
  5. Click OK or Apply.

Precision Control for Printing

Precision of printed results can be controlled using aelPushSignifDigits.

Example

aelPushSignifDigits(4)
rn             37.9322e-18    fn             0              total
37.9322e-18
aelPushSignifDigits(8)
rn             37.932238e-18  fn             0              total          
37.932238e-18

Using SKILL to Display Tabular Data

You can use the SKILL language for queries to request other kinds of simulation results, to build output format macros, and to automate test and result reporting sequences. The syntax for queries is shown at the beginning of the line in the Results Display window.

To display… Type this command in the CIW

A list of operating-point parameter names and their values for R1

OP("/R1","??")

A list of just the operating-point parameter names for R1

OP("/R1","?")

A single operating-point parameter (v for voltage, for example) and its value for R1

OP("/R1","v")

A list of transient operating-point parameter names and their values for C1

OPT("/C1","??")

A list of just the transient operating-point parameter names for C1

OPT("/C1","?")

A single transient operating-point parameter (i for current, for example) and its value for C1

OPT("/C1","i")

A list of model parameter names and their values for Q1

MP("/Q1","??")

A list of just the model parameter names for Q1

MP("/Q1","?")

A single model parameter (is for saturation current, for example) and its value for Q1

MP("/Q1","is")

Noise parameter information for a device with only one noise parameter (a resistor R4, for example)

VNP("/R4")

A list of noise parameter names for a device with more than one noise parameter (a device D24, for example) and their values

VNPP("/D24","??")

A list of just the noise parameter names for a device with more than one noise parameter (a device D24, for example)

VNPP("/D24","?")

A single noise parameter (rs for saturation resistance, for example) and its value for a device with more than one noise parameter (a device D24, for example)

VNPP("/D24","rs")

Annotating Simulation Results

You can annotate data onto the schematic to show the parameters, operating points, net names, currents and voltages of the design components. You can also change the existing annotations using the context menu or the annotation setup form.

To annotate data on the schematic,

To annotate instances selectively, use the View – Annotations – Setup command in the Schematic window. For more information on annotating data on the Schematic, see Annotating Data on the Schematic Window section in the Virtuoso Schematic Editor L User Guide.

Annotating DC Node Voltages

To annotate DC node voltages,

Annotating DC Operating Points

To annotate DC operating points,

Annotating DC Currents

To annotate DC currents,

Annotating Transient Voltages

To annotate transient voltages,

  1. In the Schematic window, choose View – Annotations – Transient Node Voltages.
    The Annotating Transient Results form appears.
  2. Type the transient time point in the Time field, and click OK.
    Alternatively, you can also type the transient time points in the Sim Time text box on the Schematic toolbar.

Annotating Transient Currents

To annotate transient currents:

  1. In the Schematic window, choose Results – Annotate – Transient Currents. Alternatively, right-click in the Results tab and choose Annotate - Transient Currents
    The Annotating Transient Results form appears.
  2. Type the transient time point in the Time field, and click OK.
    Alternatively, you can also type the transient time points in the Sim Time text box on the Schematic toolbar.

Annotating Transient Operating Points

To annotate final transient operating points,

  1. In the Simulation window or the Schematic window, choose Results – Annotate – Transient Operating Points. This will annotate the operating point data for the final timepoints.

To annotate infotimes transient operating points,

  1. In the Simulation window or the Schematic window, choose Results – Annotate – Transient Operating Points.
    The Annotating Transient Operating Points form appears.
  2. Select the transient time point in the Time drop-down field. This field lists the choices of timepoints at which the operating point data is stored.This will annotate the operating point data for the selected timepoint saved.
  3. Click OK or Apply. These two buttons essentially perform the same operation except that the Apply button does not close the form enabling the user to select another timepoint and click Apply again to annotate data for a different timepoint. Clicking on the Cancel button will cancel entire operation.

Important Points to Note:

Annotating AC Operating Points

To annotate AC operating points,

Specifying the Data Directory for Labels

To specify the simulation data directory (run directory) for labels,

  1. In the Schematic window, choose View – Annotations – Setup.
    The Annotation Setup form appears.
  2. In the Simulation Data Directory field, type the path to the simulation run directory and click OK.
You do not need to use this form if

Saving and Removing Annotated Labels

To save the annotation settings, choose File – Save from the Annotation Setup form. For more information on saving the annotation settings, see Saving Annotation Settings section in the Virtuoso Schematic Editor L User Guide.

Conditional Search for Results

After running a simulation, you can search the results for components in the saturation region, breakdown region, or any user-defined region. To do a conditional search for results, choose Results – Circuit Conditions from the Simulation menu. Follow the procedure below to search for circuit conditions.

  1. Run a simulation.
    You must run a DC operating-point analysis to use the circuit conditions capability.
  2. Choose Results – Select and indicate the results that you wish to search.
  3. Choose Results – Circuit Conditions from the Simulation window.
    The Circuit Conditions form appears:
    For detailed information about the form, see Circuit Conditions.
  4. Choose device operating conditions.
    You can choose to view components in the saturation (for BJT devices), linear (for MOS devices), or breakdown region.
    The appropriate model parameters must be set for the simulator to calculate these conditions. These features might not be available for simulators other than spectre.
  5. Set up User Defined Conditions.
    You use the cyclic and type-in fields to create the custom conditions you want to search for.
  6. View the results of the conditions you chose by doing the following.
    • Click Place to highlight the instances that meet the specified conditions on the schematic.
    • Click Print to print the values of instances that meet the specified conditions in a print window.
    • Click Clear to de-highlight all the instances on the schematic.
  7. Clicking on the Options button will bring up a form where you can specify filter and sort conditions.

In the Filter out Components by Model Name section, you can enter filters using the cyclic field displaying all the component types and the text entry field to type in model names. After you have selected the component type and entered a model name, press Add to add the filter to list of filters. You can select one or more filters in the list and then click Delete to delete the filters. The filters are active only when the Filter out Components by Model Name check box is selected. When the filters are active, any component that matches a filter will be filtered out when you click the Place button or the Print button.

The next section is Sort components by Parameter Value. Users can use the two cyclic fields to enter sorting criteria for a component type. When this section is active (Boolean is on) the output from Print for user defined conditions will be sorted according to the sort variable for given component type.

Form Field Descriptions

Setting Plotting Options

Print After refers to the commands located in the Plot Outputs menu.

Each Selection specifies that the plot is printed after each node is selected.

All Selections Are Made specifies that none of the plots are printed until all of the nodes have been selected. You can select more than one node and click the Escape key when finished, and all the selected nodes are printed at the same time (into a table).

Direct Plots Done After refers to the commands located in the Direct Plot menu.

Each Selection specifies that the plot is drawn after each node is selected.

All Selections Are Made specifies that none of the plots are drawn until all of the nodes have been selected. You can select more than one node and click the Escape key when finished, and all the selected nodes are printed at the same time (into a table).

For the calculator print and printvs functions, you can use append mode and have more than one expression in the buffer and use print or printvs to print into a table.

Annotations selects information to be displayed in the graph window.

Design Name displays the design name in the graph window.

Simulation Date displays the simulation run date in the graph window.

Temperature displays the temperature associated with the plotted results in the graph window.

Design Variables displays the names and values of user-created variables in the graph window.

Scalar Outputs displays simulation results that evaluate to scalar values in the graph window.

XF Results

Plotting Mode

Append adds the new plot to existing plots that are already displayed in the graph window.

Replace replaces existing plots with the new plot.

New SubWin adds the plot to a new subwindow.

New Win adds the plot to a new window.

Function

Voltage Gain is a calculation of voltage over voltage.

Transimpedance is a calculation of voltage over current.

Current Gain is a calculation of current over current.

Transconductance is a calculation of current over voltage.

Modifier

Magnitude (the default setting) plots the magnitude of the selected signal.

Phase plots the phase of the selected signal.

dB20 plots the magnitude in dB20.

Real plots the real component of the signal.

Imaginary plots the imaginary component of the signal.

Replot triggers the plotting of the selected instance or instance terminal with modified specifications.

Add To Outputs followed by Replot adds the output to the Table Of Outputs list box in the Simulation window.

Select instance on schematic or Select instance terminal on schematic prompts you to select the appropriate instance or terminal from the schematic.

S-Parameter Results

Plotting Mode

Append adds the new plot to existing plots that are already displayed in the graph window.

Replace replaces existing plots with the new plot.

New SubWin adds the plot to a new subwindow.

New Win adds the plot to a new window.

Function specifies the S-parameter or noise-parameter function to plot.

SP is S-parameters.

ZP is Z-parameters.

YP is Y-parameters.

HP is H-parameters.

GD is group delay.

VSWR is voltage standing wave ratio.

NFmin is minimum noise figure.

Gmin is the source reflection coefficient corresponding to NFmin.

Rn is equivalent noise resistance.

NF is noise figure.

B1f is the intermediate term for Kf, the Rollet stability factor.

Kf is the Rollet stability factor.

GT is transducer gain.

GA is available gain.

GP is power gain.

NC is noise circles.

GAC is available gain circles.

GPC is power gain circles.

LSB is load stability circles.

SSB is source stability circles.

Plot Type specifies the plot format. Option availability is a function of the selected function.

Auto uses the format in the current graph window unless that format is unsuitable for the function.

Rectangular specifies curves plotted against frequency.

Z-Smith specifies curves plotted on a Smith chart with impedance overlay.

Y-Smith specifies curves plotted on a Smith chart with admittance overlay.

ZY-Smith plots the signals to an Immittance Smith chart. In the Immittance Smith chart (ZY-Smith), both Z Smith and Y Smith grids are plotted on the same chart.

The Immittance Smith Chart has two grids: red and green. The red grid represents the Impedance or Z Smith grid, whereas the green grid represents the Admittance or Y Smith grid. On the red grid, the region above the x axis represents inductive impedances (positive imaginary parts) and the region below the x axis represents capacitive impedances (negative imaginary parts)

Polar specifies curves plotted in polar (mag/angle) coordinates.

Modifier , which is used only for rectangular plots, specifies the modifier the analog circuit design environment uses to reduce complex data for two-dimensional presentation. Option availability depends on the selected function; some functions, such as stability factor, do not require a modifier.

Magnitude plots the magnitude of complex or scalar quantities.

Phase plots the phase of complex quantities in degrees.

dB20 plots the magnitude in dB.

Real plots the real part of complex quantities.

Imaginary plots the imaginary part of complex quantities.

Sweep selects a set of circles to be plotted against frequency or dB. (Sweep appears on the form only when you are plotting circles and have selected the NC, GAC, or GPC function.)

You can plot noise and gain circles at a single dB value for a range of frequencies or at a single frequency for a range of dB values.

When plotting stability circles, you can specify a frequency range. Use SSB to plot stability circles at the input port, and use LSB to plot those at the output port. You can specify a limited frequency range for these contours.

Level (dB) specifies the gain or noise figure value in dB for circles plotted against frequency.

Frequency Range defines Start, Stop, and Step for circles plotted at the specified dB value.

If you do not type in values for the frequency range, a circle is plotted for every simulated frequency for which a circle with the specified value exists.

Frequency specifies the spot frequency for circles plotted against a design variable.

Level Range defines Start, Stop, and Step for circles plotted for the specified spot frequency.

Gain is the value of gain in dB for which gain circles are plotted.

Noise is the value of noise figure in dB for which noise circles are plotted.

Plot buttons and cyclic fields at the bottom of the form generate the plots. For S, Y, Z, or H parameters, generate plots for ports 1 through 3 by clicking the appropriate button at the bottom of the form. To generate plots for the other ports, use the cyclic fields beside the buttons to specify the output and incident ports, and then click the S, Y, Z, or H button to generate the plot.

Circuit Conditions

Device Operating Conditions

These checkboxes let you highlight components in saturation and in breakdown. When the Annotate Place button is pressed, components in breakdown, saturation, or both are highlighted on the schematic with a colored box. The color of the box is chosen by the color cyclic field next to each field.

Saturation BJT or Linear MOS

An instance is highlighted for

Breakdown

For Spectre breakdown, an instance is highlighted if

For the simulator to calculate breakdown or Saturation, the appropriate model parameters need to be set.

User-Defined Conditions

Enable uses the cyclic field to select yes or no to enable or disable a condition.

Color shows the color with which you want to highlight instances meeting a condition.

Component Shows the type of component for which you want to create conditions.

Lower Bound Specifies the lower boundary of a parameter’s value.

Upper Bound Specifies the upper boundary of a parameter’s value.

Parameter is an operating-point parameter you choose from the cyclic field. The Lower Bound and Upper Bound values apply to the selected parameter.

and/or sets Boolean arguments to a condition. When and is used, both conditions must be met for an instance to be highlighted. When or is used, either condition must be met for an instance to be highlighted. Both operators have the same precedences.

Add adds another compound condition to the existing entries in the table. When this button is clicked, a new row is added to the bottom of the table so that a designer can specify another search condition.

Delete removes a condition from the table. When this button is clicked the selected entries in the table are removed. You select entries by clicking on a row in the User Defined Conditions box.

Change lets you modify a user-defined condition. You must select the condition before modifying it.

Clear lets you clear all the entries from the User Defined Conditions box.

Plotting Associated Signals

You can plot all the signals used in an expression directly from the Results tab.

On the Outputs Setup tab, consider the Compare expression, which compares two waveform signals: VT("/vin") and VT("/vout").

To plot the signals used in the expression, do the following:

  1. Run the simulation to evaluate the expression.
    The results are displayed in the Results tab.
  2. On the Results tab, right-click the Nominal column, and then choose one of the following commands from the context menu:
    • Plot Associated Signals — Plot All Signals: Plots all the associated signals used in the expression.
    • Plot Associated Signals — <Signal 1>: Plots the first signal used in the expression. For example, VT("/vin").
    • Plot Associated Signals—<Signal 2>: To plot the second signal used in the expression. For example, VT("/vout").

    In addition to the associated signals, you can also plot the first-level dependent used in the expression.
    Consider the Composite expression, as shown in the following figure:
    If you plot the associated signals of the expression, the first-level dependent, Value, can also be plotted directly from the Results tab, as shown in the following figure.


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