C
Environment Variables for Spectre Simulator Options Form
This section describes the environment variables that you can set in the .cdsenv file to specify default values for Spectre simulator options or analysis options.
Important points to note:
- The default values specified for the variables in this document indicate the default values specified for these variables in the $CDSHOME/tools/dfII/etc/tools/spectre/.cdsenv file.
-
If the default value of a variable is specified as an empty string value(
"") or as"default", Spectre uses the in-built default value for that variable. For example, the default value forspectre.hb noiseoutis"". If you do not modify this value in Virtuoso, while running the simulation, Spectre internally sets it to the in-built default value"usb". For more details, refer Spectre Circuit Simulator Reference Guide.
You can set or customize the Spectre simulation options using the Simulator Options form in ADE. This chapter provides details of all available options on the following tabs of the Simulator Options form and their respective environment variables:
- Simulator Options - Main Tab
- Simulator Options - Algorithm Tab
- Simulator Options - Component Tab
- Simulator Options - Check Tab
- Simulator Options - Annotation Tab
- Simulator Options - Miscellaneous Tab
spectre.opts
| Simulator Options - Main Tab | |
| Simulator Options - Algorithm Tab | |
| Simulator Options - Component Tab | |
| Simulator Options - Check Tab | |
| Simulator Options - Annotation Tab | |
| Simulator Options - Miscellaneous Tab | |
Simulator Options - Main
checklimitskipinsts
spectre.opts checklimitskipinsts string any_string_value
Description
Specifies the array of instances to be skipped in device checking. Instances can have any wildcard symbols.
GUI Equivalent
generalnoiseinst
spectre.opts generalnoiseinst string any_string_value
Description
List of instances to be considered for noise contribution.
GUI Equivalent
generalnoiseinstonoff
spectre.opts generalnoiseinstonoff string any_string_value
Description
Specify whether to enable ("on") or disable ("off") the noise contribution for the instance list given in the generalnoiseinst cdsenv.
GUI Equivalent
highvoltage
spectre.opts highvoltage string any_string_value
Description
Enables optimized Spectre settings for high voltage designs including voltage, and current binning, excluding VerilogA and dangling nodes from convergence checks, and optimized large capacitance handling. Possible values are 'no' and 'yes'.
GUI Equivalent
iabstol
spectre.opts iabstol string any_string_value
Description
Convergence criterion for absolute current tolerance.
GUI Equivalent
multithread
spectre.opts multithread string any_string_value
Description
Enable or disable multithreading capability. When multithreading is enabled but the number of threads (nThreads) is not specified, Spectre will automatically detect the number of processors and select the proper number of threads to use.
GUI Equivalent
noiseOffType
spectre.opts noiseOffType toggle { thermal | flicker | shot | ign | all }
Description
Disable specific noise sources for the list of instances given with the cdsenv generalnoiseinst.
The default is (nil nil nil nil nil).
envSetVal("spectre.opts" "noiseOffType" 'toggle '(t nil t nil nil))
GUI Equivalent
noiseOnType
spectre.opts noiseOnType toggle { thermal | flicker | shot | ign | all }
Description
Enable specific noise sources for the list of instances given with the cdsenv generalnoiseinst.
The default is (nil nil nil nil nil).
envSetVal("spectre.opts" "noiseOnType" 'toggle '(t nil t nil nil))
GUI Equivalent
nthreads
spectre.opts nthreads string any_string_value
Description
Specifies the number of threads for multithreading.
GUI Equivalent
reltol
spectre.opts reltol string any_string_value
Description
Relative convergence criterion.
GUI Equivalent
residualtol
spectre.opts residualtol string any_string_value
Description
Tolerance ratio for residual (multiplies reltol).
GUI Equivalent
temp
spectre.opts temp string any_string_value
Description
GUI Equivalent
tempeffects
spectre.opts tempeffects string any_string_value
Description
Temperature effect selector. If tempeffect = vt, only thermal voltage varies with temperature; if tempeffect = tc, parameters that start with tc are active and thermal voltage is dependent on temperature; and if tempeffect = all, all built-in temperature models are enabled.
GUI Equivalent
tnom
spectre.opts tnom string any_string_value
Description
Temperature measurement of the default component parameter
GUI Equivalent
vabstol
spectre.opts vabstol string any_string_value
Description
Convergence criterion for absolute voltage tolerance.
GUI Equivalent
Simulator Options - Algorithm
convdbg
spectre.opts convdbg string any_string_value
Description
Specifies the option to diagnose convergence issues and identify problem areas. Possible values are "none", "status" and "detailed".
GUI Equivalent
dc_pivot_check
spectre.opts dc_pivot_check string any_string_value
Description
During DC analysis, the numeric pivoting is only performed when bad pivot is detected.
GUI Equivalent
dptran_gmethod
spectre.opts dptran_gmethod string any_string_value
Description
Stamp gdev, gnode, or both in the dptran (homotopy) methods. Possible values are 'dev', 'node' and 'both'.
GUI Equivalent
gmethod
spectre.opts gmethod string any_string_value
Description
Stamp gdev, gnode, or both in the homotopy methods (other than dptran).
GUI Equivalent
gmin
spectre.opts gmin string any_string_value
Description
gmin (conductance) is added to each nonlinear branch of the device to prevent simulation non-convergence. Large gmin impacts accuracy of current probe, small gmin may cause circuit convergence issue. For circuit that is sensitive to leakage current, it is recommended to set gmin to a small value or zero.
GUI Equivalent
gmin_check
spectre.opts gmin_check string any_string_value
Description
Specifies that effect of gmin should be reported if significant. Possible values are 'no', 'max_v_only', 'max_only' and 'all'.
GUI Equivalent
gmindc
spectre.opts gmindc string any_string_value
Description
Minimum conductance across each non-linear device in DC analysis. If gmindc is not specified, the value of gmindc will be equal to gmin.
GUI Equivalent
homotopy
spectre.opts homotopy string any_string_value
Description
Method used when there is no convergence on initial attempt of DC analysis. Possibly values are 'none', 'gmin', 'source', 'dptran', 'ptran', 'all'.
GUI Equivalent
icpriority
spectre.opts icpriority string any_string_value
Description
Set the ic priority order. If set to netlist, the order from lowest to highest is readNS, netlist NS, readIC, netlist IC. If set to file, the order from lowest to highest is netlist NS, readNS, netlist IC readIC.
GUI Equivalent
ilimit
spectre.opts limit string any_string_value
Description
Limiting algorithms to aid DC convergence. Possibly values are 'delta', 'log' and 'dev'.
GUI Equivalent
nonconv_topnum
spectre.opts nonconv_topnum string any_string_value
Description
Top number of non-convergence nodes to be printed.
GUI Equivalent
pivabs
spectre.opts pivabs string any_string_value
Description
Specifies the absolute pivot threshold.
GUI Equivalent
pivotdc
spectre.opts pivotdc string any_string_value
Description
Use numeric pivoting on every iteration of DC analysis. Possible values are "no" and "yes".
GUI Equivalent
pivrel
spectre.opts pivrel string any_string_value
Description
Specifies the relative pivot threshold.
GUI Equivalent
preorder
spectre.opts preorder string any_string_value
Description
Try this option when simulation runs out of memory or if the simulation is unreasonably slow for the size of your design. It controls the amount of matrix pre-ordering that is done and may lead to much fewer matrix fill-ins in some cases. Known cases include designs with very large number of small resistors and large number of behavioral instances containing voltage based equations. Possible values are "partial" and "full".
GUI Equivalent
rabsclamp
spectre.opts rabsclamp string any_string_value
Description
When rabsclamp=value is specified, all instance resistors with absolute R<value are clamped to value.
GUI Equivalent
rabsshort
spectre.opts rabsshort string any_string_value
Description
When this option is set, all fixed value resistors with absolute value of R<=rabsshort are shorted.
Default value is 0 for Spectre, and 1m for APS. Rabsshort can additionally be applied to variable resistors using the option 'short_cut_var_elem=yes'.
GUI Equivalent
rebuild_matrix
spectre.opts rebuild_matrix string any_string_value
Description
If set to yes, rebuild circuit matrix at the beginning of ac, dc, dcmatch, montecarlo, pz, stb, sweep, tdr, and tran analyses. This is to ensure consistent matrix ordering at the beginning of the analyses for consistent results. Notice that rebuild circuit matrix can result in performance overhead. Possible values are "no" and "yes".
GUI Equivalent
rforce
spectre.opts rforce string any_string_value
Description
Resistance used when forcing nodesets and node-based initial conditions.
GUI Equivalent
rthresh
spectre.opts rthresh string any_string_value
Description
All instance resistors that have resistance smaller than global rthresh will use resistance form, unless their instance parameter or model parameter overwrites it. Note that resistance form of any resistor is set at the beginning of simulation and cannot be changed later, so altering the value of rthresh is of no use. You will have to start a new run if you want a different rthresh for your circuit
GUI Equivalent
try_fast_op
spectre.opts try_fast_op string any_string_value
Description
Speed up the DC solution. For hard-to-converge designs, this feature fails and other methods are applied. In corner cases, this feature may have negative effects. If the DC analysis is unusually slow, the memory usage of the processes keeps increasing, or if DC analysis gets stuck even before homotopy methods start, set this option to "no".
GUI Equivalent
Simulator Options - Component
approx
spectre.opts approx string any_string_value
Description
Specifies the use of approximate models. Difference between approximate and exact models. Possible values are 'yes' and 'no'.
GUI Equivalent
auto_minductor
spectre.opts auto_minductor string any_string_value
Description
Automatic insertion of missing mutual inductor coupling. Possible values are 'yes' and 'no'.
GUI Equivalent
vth_vdsmin
spectre.opts ivth_vdsmin string any_string_value
Description
Minimum Vds in constant current Vth calculation.
GUI Equivalent
ivthl
spectre.opts ivthl string any_string_value
Description
Length offset for constant current Vth.
GUI Equivalent
ivthn
spectre.opts ivthn string any_string_value
Description
GUI Equivalent
ivthp
spectre.opts ivthp string any_string_value
Description
GUI Equivalent
ivthw
spectre.opts ivthw string any_string_value
Description
Width offset for constant current Vth.
GUI Equivalent
imacromodels
spectre.opts macromodels string any_string_value
Description
Determine whether circuit contains macromodels; at times, setting this parameter to yes helps improve performance
GUI Equivalent
maxrsd
spectre.opts maxrsd string any_string_value
Description
Use approximation for drain/source parasitic resistors which are less then maxrsd. Applies to bsim3v3, bsim4 mosfet models
GUI Equivalent
nport_default_passivity
spectre.opts nport_default_passivity string any_string_value
Description
Check and enforce passivity of S-parameter for all nport instances. Default is "disable", which means this global option has no effect. If set to a value other than "disable", all nport elements in the netlist without a value for 'passivity' explicitly set, will have their 'passivity' argument set to the same value as specified in this global option. If an nport instance already has the 'passivity' option specified, the instance option will take priority if both are present.
Possible values are "no", "check", "enforce", "fit_weak_enforce", "fit_enforce" and "disable".
GUI Equivalent
nportcompress
spectre.opts nportcompress string any_string_value
Description
Nport compression improves the efficiency of S-parameter simulation of large nport files when a certain percentage of the ports is unused, i.e., open or short circuited. Nport compression does not impact simulation accuracy. This option turns off compression if set to no and attempts to force compression if set to yes. If left unspecified, compression is on if N>=10 and the ratio of used ports is less than or equal to 0.8. Possible values are "no" and "yes".
GUI Equivalent
nportcompressfiledir
spectre.opts nportcompressfiledir string any_string_value
Description
The directory where the compressed nport S-parameter file is written to. If unspecified, it is stored in outdir.
GUI Equivalent
nportirfiledir
spectre.opts nportirfiledir string any_string_value
Description
The directory to which the nport impulse response file will be written. If it is not specified, the file will be written to /home/<username>/.cadence/mmsim/. If a relative path is specified, the path is relative to the current working directory
GUI Equivalent
nportirreuse
spectre.opts nportirreuse string any_string_value
Description
Reuses impulse responses data for all nport instances. If set to "no", disables this feature. Possible values are "no" and "yes".
GUI Equivalent
nportunusedportgmin
spectre.opts nportunusedportgmin string any_string_value
Description
Default is 0, which leaves the port open-circuited. A small value loads open-circuited ports with a finite but large resistance. This introduces a small error in the response, but it induces losses which help obtain a passive response.
GUI Equivalent
nportunusedportrmin
spectre.opts nportunusedportrmin string any_string_value
Description
Default is 0, which leaves the port short-circuited. A small value will insert a small resistance in place of short circuited ports. This introduces a small error in the response, but it induces losses which help obtain a passive response.
GUI Equivalent
nportbbsversion
spectre.opts nportbbsversion string any_string_value
Description
Controls the BBspice version used for S-Parameter fitting. Possible values are "1" and "2". When set to 1, the BBspice version 1 is selected. If set to 2, the BBspice version 2 is selected.
GUI Equivalent
nportbbsfittedfiledir
spectre.opts nportbbsfittedfiledir string any_string_value
Description
Specifies the path to the directory where Spectre places the BBspice fitted S-Parameter file.
By default, this file is saved in a directory named BBSpiceOutput.
../outfolder, it will be considered in relation to the working directory of Spectre.GUI Equivalent
minr
spectre.opts minr string any_string_value
Description
All parasitic resistors inside devices less than global minr will be removed. The order of checking devices is the follows: 1. Check if resistors are smaller than local minr. If yes, check if it is a MOSFET or BJT. If it is a MOSFET, drop the resistor, if it is BJT, clamp to the minr value, and give a warning message for both cases. 2. Check global minr, All Parasitic resistors less than global minr are removed and a warning message is issued. 3. If the resistor is not removed and is smaller than 0.001, issue a warning
GUI Equivalent
scale
spectre.opts scale string any_string_value
Description
Device instance scaling factor
GUI Equivalent
scalefactor
spectre.opts scalefactor string any_string_value
Description
ScaleFactor for Device Model Technology Scaling. The options parameter scalefactor enables device model providers to scale device technology independent of the design dimension scaling done by circuit designers. The resulting device instance scaling is defined by 'scale * scalefactor'. If the foundry uses a technology scale factor of 0.9 (scalefactor=0.9), and the circuit designer uses a design scale factor of 1e-6 (scale=1e-6), then the compounded scaling of the device instance dimension is 0.9e-6. Unlike options parameter scale, scalefactor cannot be used as a netlist parameter and cannot be altered or used in sweep statements.
GUI Equivalent
scalem
spectre.opts scalem string any_string_value
Description
GUI Equivalent
tmevthmod
spectre.opts tmevthmod string any_string_value
Description
TSMC constant vth calculation. By default it is not activated. Possible values are "0" and "1".
GUI Equivalent
vthmod
spectre.opts vthmod string any_string_value
Description
Vth output selector. 'std' outputs model equation Vth; 'vthcc' outputs constant current Vth and may impact simulation performance. Possible values are "std" and "vthcc".
GUI Equivalent
Simulator Options - Check
checklimitdest
spectre.opts checklimitdest string any_string_value
Description
Destination(s) where violations are written. Possible values are 'file', 'psf' and 'both'.
GUI Equivalent
checklimitfile
spectre.opts checklimitfile string any_string_value
Description
File to which assert violations are written.
GUI Equivalent
checklimitskipfile
spectre.opts checklimitskipfile string any_string_value
Description
Specifies the file which contains the subcircuit masters or subcircuit master patterns to be skipped in device checking. Patterns can have any wildcard symbols.
GUI Equivalent
checklimitskipsubs
spectre.opts checklimitskipsubs string any_string_value
Description
Specifies the array of subcircuit masters or subcircuit master patterns to be skipped in device checking. Patterns can have any wildcard symbols.
GUI Equivalent
diagnose
spectre.opts diagnose string any_string_value
Description
Print additional information that might help diagnose accuracy and convergence problems. Possible values are 'no', 'yes' and 'detailed'.
GUI Equivalent
iccapcheck
spectre.opts iccapcheck string any_string_value
Description
Check if nodes with initial conditions have capacitive path to ground. IC for the node without capacitance is treated as nodeset. Possibly values are 'no' and 'yes'.
GUI Equivalent
gnshorts
spectre.opts ignshorts string any_string_value
Description
Silently ignore shorted components. Possibly values are 'no' and 'yes'.
GUI Equivalent
redefinedparams
spectre.opts redefinedparams string any_string_value
Description
Specify whether parameters can be redefined in the netlist. When set to warning or ignore, the simulator allows you to redefine parameters in the netlist. However, it honors only the last definition of the redefined parameter. Depending on the value set, the simulator displays warning messages for the redefined parameters or does not display any message. When set to error, the simulator does not allow you to redefine parameters in the netlist and displays an error message.
GUI Equivalent
opptcheck
spectre.opts opptcheck string any_string_value
Description
Checks operating point parameters against soft limits. Possible values are "no" and "yes".
GUI Equivalent
topcheck
spectre.opts topcheck string any_string_value
Description
Check circuit topology for errors. Possible values are "no", "min", "full", "fixall", "errmin" and "errfull".
GUI Equivalent
Simulator Options - Annotation
audit
spectre.opts audit string any_string_value
Description
Print time required by various parts of the simulator. Possible values are 'no', 'brief' or 'detailed'.
GUI Equivalent
cols
spectre.opts cols string any_string_value
Description
Width of screen in characters.
GUI Equivalent
colslog
spectre.opts colslog string any_string_value
Description
Width of log-file in characters.
GUI Equivalent
debug
spectre.opts debug string any_string_value
Description
Give debugging messages. Possible values are 'no' and 'yes'.
GUI Equivalent
digits
spectre.opts digits string any_string_value
Description
Number of digits used when printing numbers.
GUI Equivalent
error
spectre.opts error string any_string_value
Description
Generate error messages. Possible values are 'no' and 'yes'.
GUI Equivalent
info
spectre.opts info string any_string_value
Description
Give informational messages. Possibly values are 'no' and 'yes'.
GUI Equivalent
inventory
spectre.opts inventory string any_string_value
Description
Print summary of components used. Possibly values are 'brief', 'detailed' and 'no'.
GUI Equivalent
maxnotes
spectre.opts maxnotes string any_string_value
Description
Maximum number of times a notice is issued per analysis. Note that this option has no effect on notices issued as part of parsing the netlist. Use the -maxnotes command-line option to control the number of all notices issued
GUI Equivalent
maxnotestologfile
spectre.opts maxnotestologfile string any_string_value
Description
Maximum number of times a notice message is printed to the log file per analysis. Note that this option has no effect on notices printed as part of parsing the netlist. Use the -maxnotestolog command-line option to control the number of all notices printed to the log file
GUI Equivalent
maxwarns
spectre.opts maxwarns string any_string_value
Description
Maximum number of times a warning message is issued per analysis. Note that this option has no effect on warnings issued as part of parsing the netlist. Use the -maxwarns command-line option to control the number of all warnings issued
GUI Equivalent
maxwarnstologfile
spectre.opts maxwarnstologfile string any_string_value
Description
Maximum number of times a warning message is printed to the log file per analysis. Note that this option has no effect on warnings printed as part of parsing the netlist. Use the -maxwarnstolog command-line option to control the number of all warnings printed to the log file
GUI Equivalent
notation
spectre.opts notation string any_string_value
Description
The notation to be used to display real numbers to the screen. Possibly values are 'eng', 'sci', 'float'.
GUI Equivalent
note
spectre.opts note string any_string_value
Description
GUI Equivalent
narrate
spectre.opts narrate string any_string_value
Description
GUI Equivalent
printstep
spectre.opts printstep string any_string_value
Description
Enables Spectre to print results by equal step defined in .tran statement.
GUI Equivalent
simstat
spectre.opts simstat string any_string_value
Description
Print simulation phase statistics report. Possible values are "basic" or "detailed".
GUI Equivalent
title
spectre.opts title string any_string_value
Description
GUI Equivalent
warn
spectre.opts warn string any_string_value
Description
Display warning messages. Possible values are "no" and "yes".
GUI Equivalent
Simulator Options - Miscellaneous
additionalArgs
spectre.opts additionalArgs string any_string_value
Description
Specifies a string that adds options that are not supported through the ADE GUI.
GUI Equivalent
ahdllint
spectre.opts ahdllint string any_string_value
Description
Specifies the Spectre command line argument to enable Verilog-A linter check. Possible values are 'warn', 'error', and 'force'. This option is not available in Spectre base. It is available only in APS or XPS.
GUI Equivalent
ahdllint_maxwarn
spectre.opts ahdllint_maxwarn string any_string_value
Description
Specifies the maximum number of Verilog-A linter warning messages to be reported by the simulator for each message ID.
GUI Equivalent
ahdllint_on
spectre.opts ahdllint_on string any_string_value
Description
When set to "on", enables the AHDL Linter feature.
GUI Equivalent
flow
spectre.opts flow string any_string_value
Description
Specifies the default flow quantity.
GUI Equivalent
quantities
spectre.opts quantities string any_string_value
Description
Print quantities. If quantities=min, the simulator prints out all defined quantities; if quantities=full, the simulator also prints a list of nodes and their quantities.
GUI Equivalent
sensbinparam
spectre.opts sensbinparam string any_string_value
Description
Sensitivity for binning models. Possible values are "no", "uncorrelated" and "correlated"
GUI Equivalent
sensfile
spectre.opts sensfile string any_string_value
Description
Output sensitivity data file name.
The default is "../psf/sens.output".
GUI Equivalent
sensfileonly
spectre.opts sensfileonly string any_string_value
Description
Enable or disable raw output of sensitivity results. Possible values are "no" and "yes".
GUI Equivalent
sensformat
spectre.opts sensformat string any_string_value
Description
Format of sensitivity data. Possible values are "tabular" or "list".
GUI Equivalent
senstype
spectre.opts senstype string any_string_value
Description
Type of sensitivity being calculated. Possible values are "partial" or "normalized".
GUI Equivalent
value1
spectre.opts value1 string any_string_value
Description
Specifies the default value quantity.
GUI Equivalent
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