Hi Andrew/Shawn, I am doing a post-layout PSS+PNOISE for a 5-GHz 4-stage pseudo-differential ring oscillator . I tried, forcing complementary signals (ring-top voltage and VSS) to one of the ring output pairs from the test-bench level using ideal switches and analogLib pwl source. using "initial conditions" from ADEXL test to set complementary signals to one of the ring output pairs. In both the cases, the output log shows that the PSS runs for some time and then it says that the voltage of the ring output is too small to reliably detect the period of the oscillator. Perhaps the nodes with insignificant signal levels were chosen, or perhaps the oscillator was never properly started . Analysis "pss" was terminated prematurely due to an error . I understand that a 4-stage pseudo-differential ring has a stable operating point which might lead to latch-up problem but in transient, if I give the same set of initial conditions, I see proper oscillation of the ring. Can you tell me what is causing PSS not to converge in this case? PSS settings used are as follows, Accuracy defaults (errpreset): conservative Run transient: Yes Detect steady-state : unchecked Stop time (tsab): 20n (when ran with 100n, that doesn't help either) Oscillator: checked Oscillator node+: One of the ring nodes Oscillator node-: VSS Calculate initial conditions (ic) automatically: unchecked Method: gear2only tstabmethod: gear2only In the ADEXL test environment, I am using, +dcopt +postlayout = legacy_rf Thanks and regards, Subhadeep
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