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Design >> High-Power Design >> pss gives wrong time domain waveform
https://designers-guide.org/forum/YaBB.pl?num=1406548707

Message started by ywguo on Jul 28^th, 2014, 4:58am

Title: pss gives wrong time domain waveform
Post by ywguo on Jul 28^th, 2014, 4:58am

Hi Guys,

PSS gives wrong time domain waveform when I run pstb for a buck model. Transient analysis shows the model works. The following is the test bench of the buck model. What's wrong with my simulation? I think the default engine for pss analysis is newton-shooting, too.

Yawei

Title: Re: pss gives wrong time domain waveform
Post by ywguo on Jul 28^th, 2014, 5:09am

The following is simulation result, where the red line is transient analysis result and the blue line is the pss-tran result.

Title: Re: pss gives wrong time domain waveform
Post by raja.cedt on Jul 28^th, 2014, 6:17am

hi ywguo,
Would be nice if you can show schematic one level below. Did you check PSS log file??

Thanks,
Raj.

Title: Re: pss gives wrong time domain waveform
Post by ywguo on Jul 28^th, 2014, 10:39pm

Hi Raja,

The following is the schematic of buck, which is DUT in the previous test bench. Thank you.

Yawei

Title: Re: pss gives wrong time domain waveform
Post by ywguo on Jul 30^th, 2014, 5:41pm

I got the answer. The pss analysis is not in the argument list of initial_step in the opamp model.

Code:

analog begin
@(initial_step ("dc","ac","tran","noise","stb"))
begin
Vhi=V(vdd);
Vlo=V(gnd);
v_th=(Vhi-Vlo)/2;
end

Best Regards,
Yawei