AMS Designer with Spectre FX

Spectre FX is a next-generation FastSPICE simulator that addresses simulation challenges such as the increasing demand for performance, accuracy, and capacity from transistor-level simulators. It also addresses the requirements of ever-shrinking process nodes, the adoption of new design practices, the need for full-chip simulation, and the increasing influence of parasitic elements, which greatly increase the size and complexity of the designs to be simulated.

Unlike the other Spectre simulators, such as Spectre APS, Spectre X, and Spectre XPS, the default compatible mode in Spectre FX is SPICE, which means that you no longer need to add the +spice argument in the command line for the SPICE syntax. However, you do need to add the +spectre argument in the command line for the Spectre syntax.

Spectre FX supports only transient analysis and uses the Unified Database (UDB) format by default.

To use the Spectre FX analog simulator with Spectre AMS Designer:

• Use the +fx argument with the -spectre_args option of the xrun command. The default simulator used is SPICE. To use the Spectre simulator, specify the +spectre option.

          Example
     xrun -spectre_args "+fx +spectre"

          To change the solver, use the +preset option.

          xrun -spectre_args "+fx +spectre +preset=[lx | ax | mx| lx |vx| baseax | basemx|  baselx| basevx]"

          The simulation tolerance for voltage and current calculation can be done by setting the +speed option to lx.

     xrun -spectre_arg "+fx +spectre +preset=vx +speed=lx +mt=8"

Spectre FX supports multithreading on multi-core computer platforms. The default behavior is to use a single thread.

Example

The following command enables multithreading on eight cores.

-spectre_arg "+fx +spectre +mt=8"

Options for AMS Designer with Spectre FX

Spectre FX supports both Spectre and SPICE syntax to set the options.

• Spectre syntax: 

     SimOpt1 options option_name1=option_value option_name2=option_value …

• SPICE syntax:
  .option option_name1=option_value option_name2=option_value …

Connect Module Usage

You can enable UCM for AMS Designer with Spectre FX using the command  accurate=moderate, where moderate is the default value.

The following table shows the default value changes for the default connect modules, compared to other analog simulators.

With Spectre FX, the default IE card parameter value tr=10p lets you convert logic clocks to electrical clocks with up to 50 Giga Hertz frequency. With the parameter value tr=200p, the clock frequency is limited to 2.5 Giga Hertz.

Related Topic

Starting a Spectre FX Simulation Run