The stb analysis linearizes the circuit about the DC operating point and computes the loop gain and gain and phase margins (if the sweep variable is frequency) for a feedback loop or a gain device. Spectre can perform the analysis while sweeping a parameter. The parameter can be frequency, temperature, component instance parameter, component model parameter, or netlist parameter. If changing a parameter affects the DC operating point, the operating point is recomputed at each step.
Name stb parameter=value ...
For more information on stb analysis parameters, refer to the Stability Analysis (stb) section in the Spectre Circuit Simulator Reference manual.