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Simulators >> Circuit Simulators >> pss and pac analysis for chopper stabilized op-amp
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Message started by rames on May 25^th, 2017, 12:04am

Title: pss and pac analysis for chopper stabilized op-amp
Post by rames on May 25^th, 2017, 12:04am

Hello,
I am trying to simulate a chopper stabilized op-amp (Single output: Vout and differential input: Vi1, Vi2) in Cadence Virtuoso (PSS + PAC analyses), and seeing the output node and frequency response in rage of 1 Hz to 1K Hz.
I set the analysis parameters as shown in figures and start the simulation. After that it reported "Nil-Nil" error. I try these equations in setting outputs to plot output node and frequency response:

output node => ( (v ("/Vout")) : pss) (V)
frequency response => dB20( harmonic( v("/Vout" ?result "pac") 0) / (harmonic(v("/Vin1" ?result "pac") 0) - harmonic(v("/Vin2" ?result "pac") 0)))

But i think somewhere i made a mistake. Could you please help me?
Thanks in advence

Title: Re: pss and pac analysis for chopper stabilized op-amp
Post by Ken Kundert on May 25^th, 2017, 2:00am

Your set up looks okay to me. By simply specifying you encountered a Nil-Nil error, you have robbed the message of all its context. It would be good to show it so we can determine ...

1. What is printing the message? Is it ADE, Spectre, or something else.
2. If it is Spectre printing the message, is it PSS, PAC or something else?

Printing Nil-Nil to identify an error makes it sounds like an internal error produced by ADE, which suggests that maybe you did not set something you should have. You might want look around. If you cannot find anything, you might want to talk to Cadence. Unless this is known problem with a known workaround, it is hard for other users to help you with an internal error.

-Ken

Title: Re: pss and pac analysis for chopper stabilized op-amp
Post by Andrew Beckett on May 28^th, 2017, 9:44am

Perhaps you didn't save the signals used in the result calculation? It's hard to tell from the little information you provided, as Ken says...

Regards,

Andrew.