I have been attempting this a few various ways, each way is giving me different number results. the integrator is followed by another sc integrator so I am using noisetype=timedomain

I tried tying setting the inputs dc to cm with each having a .5 AC in opposite polarity, and make the pss period long enough to see integration in both chop phase. but this didnt seem to work. I also tried allowing it to integrate a signal and resetting the integrating cap periodically, but the frequency of the reset impacted noise results. I also was told by the local cadence rep spectre wouldnt work with chopping...but az and chopping seem like common techniques that it would be designed to handle.  And lastly I was recommended by a coworker to attempt to make a .va SH  and add the SH delay output to the non delayed output to basically try to cancel the low freq noise out to mimic statistical cancellation a chopper would see over time.

Are any of these the right method? Is there a tried and true procedure for handling chopping circuits?
-Pb

You need to run a PSS analysis before running PAC. PSS analysis requires that the have a periodic steady-state solution. It sounds like your integrator is actually integrating, so that output is not periodic. To run PSS/PAC you probably want to remove the large signal input, provide feedback so that there is a stable periodic operating point, and then run PSS/PAC.

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That person is wrong.
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PAC just computes voltages and currents. The testbench determines what is measured.
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There must be a periodic solution, so the chopping and sampling frequencies must be co-periodic. Use the lowest common multiple as the fundamental frequency.
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Linearization means that it is as if the input signal is very small, so small that it cannot generate a nonlinear response.

-Ken

Please remember that we cannot see your circuit or your testbench, so it is difficult to say with any confidence what you are doing. It sounds like you are running the integrator open loop, which is probably wrong.

PNoise can compute the input referred noise directly. No need for you to combine the PAC results with the PNoise results to get input referred noise. Just specify the input source to the PNoise analysis and it will work.

-Ken

To get meaningful results, the testbench should try to mimic the way the circuit is intended to be used. Since integrators have very large gains, one tends to use them in one of two ways:

• They are embedded in a feedback loop (ex. in active filters).
• They are active for a fixed period of time and then reset.

To use SpectreRF, you need a periodic solution. That is generally easy in the first case, you include the feedback in the testbench and then run PSS with the clocks applied and the input amplitude set to zero. In the second case, you would add reset circuitry to your testbench and allow the integrator to operate for a fixed number of cycles (the PSS fundamental would then be set to the reset frequency).

After the PSS analysis you would run the PNoise analysis. If in your overall system the output of the chopper will be sampled, then you should probably use a sampled noise analysis. This is because only the noise at the sample point is of interest, noise at other time is ignored by the overall system because of the sampling. If instead the chopper is driving a continuous time filter then you should use 'sources' ('sources' is a non-descriptive name, a more descriptive name would be 'time-average noise').

I don't understand your comment on the input referred noise. I don't know what the 'very input' is. If there is additional circuitry between the true input and the input modeled in your testbench, then you can get the true input referred noise by adding that additional circuitry, or at least a model of that circuitry, to your testbench.

-Ken

Sorry I messed up with the input , no issue there.

as far as adding feedback, As long as the system works without using reset, the noise numbers shouldnt be affected correct? example  having a system feedback that swaps the inputs every three samples vs every 5 samples. the noise/xfer function should be the same since the integrating cap is never losing charge due to a discontinuous reset.