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Turning off non-linearity contribution of cells

FPMKh 5 months ago

Hi,
Spectre version: 23.1.0.594.isr12

I was wondering if we can turn off non linearity contribution of a certain blocks in the design. Something similar to what is possible for noise analysis where you can turn ON/OFF certain blocks in the noise simulation.
I run linearity simulation using large signal transient.

Thank you.

Andrew Beckett 5 months ago

No - not sure this makes sense given how transient circuit simulation works. You can linearise the circuit equations around a particular operating point, but making it completely linear would be rather hard... (how would a switch or an inverter suddenly become linear?)

There is the "compression distortion summary" specialised analysis in ac/pac/hbac analyses which allow you to do an AC analysis and choose some of the devices to be weakly non-linear, and it makes those devices non-linear one at a time, and this allows you to look at the contributors to distortion - a bit like you can with a noise analysis.

This is covered in this rapid adoption kit: Operational Amplifier (OpAmp) Stability, CMRR, PSRR, Noise, Slew Rate, THD, Compression Distortion Measurements from ADE Explorer

However, I don't think that's quite what you are asking.
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FPMKh 5 months ago in reply to Andrew Beckett

Thank you, Andrew.
Compression distortion summary could be of help. When I tried to run it, I get the following error:

Error found by spectre during PAC analysis `pac'.
ERROR: More than one frequency matches are found between input and output signals

PSS finished just fine.

Do you know where could I be making a mistake?
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Andrew Beckett 5 months ago in reply to FPMKh

How have you set up the pac analysis? Can you share the analysis statements from the input.scs file?

Andrew
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