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Open source alternative for PSS, PAC and Pnoise

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Junior Member level 2
Jul 20, 2015
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Hi, I use Spectre for all my analog design simulations. Unfortunately, I am writing a proposal that requires some simulations and I cannot simulate using Virtuoso/Spectre for legal reasons. I need to simulate an N-Path filter "like" circuit and require PSS, PAC and Pnoise or some alternative that will get me similar results... but like I said, I can't use Virtuoso or Spectre.

I can use ADS though and I'm familiar with ngspice. ADS has a "harmonic balance" simulation framework for its PSS simulations but its not nearly as intuitive as Spectre's. I'm not even sure I can do what I need to do in ADS but it looks promising. Same for ngspice.

Does anyone have any suggestions?


PSS is a property technique of Cadence and nobody can use that without written authorization.
But I'll tell you that HB results are more accurate in my opinion. PSS is not a perfect technique as claimed.

PSS just describes an analysis that can be performed using different methods e.g. shooting or HB. ADS has their version of PSS but it only uses HB. I agree that what we all call "PSS" in industry usually means Spectre's but ngspice also does PSS and so does ADS albeit its not as nice.

Maybe I wasn't clear in my original question. I know there are other SW platforms that do this. I'm 90% sure ADS will do it but not exactly sure how. I want to get the noise figure and gain vs. freq of a switched capacitor circuit. This requires PSS. I can run HB (e.g. PSS) in ADS but can't do a small signal AC analysis (e.g. PAC). I can probably run many transients and use MATLAB to calculate the gain and maybe that is the way to go but is there an easier way?

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