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SpectreRF pnoise simulation: sampled output noise of a chopping amplifer

SpiceMonkey

Hello, everyone!

For a sampled output noise of a choping amplifer: how to simulate "chopping modulation" and "sampling aliasing" together?

For a chopping amplfier, choping frequency=1MHz, PSS is automaticaly set to 1MHz by software:
1) in timeaverage pnoise simulation, 1/f noise is moved to choping frequency; This is expected result.
2) in sampled pnoise simulation, we observe the aliasing due to sampling. But 1/f noise is not modulated and still in low frequency; This is not all my expected result.

The reason why I try to use sampled simulation is that:
1) A oversampling ADC is after this choping amplfier. What I want to calculate is "discrete sampled noise" rather than "continues noise".
2) I want to observe both "choping mudulation" and "sampling aliasing".

My thinking:
We know sampling frequency must at least twice lager than signal frequency,after choping, the output signal is actually 1MHz. But in sampled pnoise simultion the sampling frequency seems also to be 1MHz (PSS frequency). The sampled pnoise simulation gives the result that the 1/f noise is not moved to choping frequency, but it does show aliasing due to 1MHz sampling.

My Question:
1) I think if sampling frequecy is 2MHz, then I could get correct sampled output noise, is this possible in spectreRF?
2) How to simulate "chopping modulation" and "sampling aliasing" together?

[Simulator] Spectre 19.1

  • What is "wrong"? Provided you don't sweep the noise analysis beyond half the PSS fundamental, the results should include all the noise aliased into that band.

    So I'm not sure why you would need to do what you're asking for.

    Andrew

  • in reply to Andrew Beckett

    Thank you Andrew, sorry for my previous ambiguous post.
    For a choping amplfier, choping frequency=1MHz, PSS is automaticaly set to 1MHz by software:
    1) in timeaverage pnoise simulation, 1/f noise is moved to choping frequency; This is expected result.
    2) in sampled pnoise simulation, we observe the aliasing due to sampling. But 1/f noise is not modulated and still in low frequency; This is not all my expected result.

    The reason why I try to use sampled simulation is that:
    1) A oversampling ADC is after this choping amplfier. What I want to calculate is "discrete sampled noise" rather than "continues noise".
    2) I want to observe both "choping mudulation" and "sampling aliasing".

    We know sampling frequency must at least twice lager than signal frequency,after choping, the output signal is actually 1MHz. But in sampled pnoise simultion the sampling frequency seems also to be 1MHz (PSS frequency). The sampled pnoise simulation gives the result that the 1/f noise is not moved to choping frequency, but it does show aliasing due to 1MHz sampling.
    So, is it possible to show both "modulation (choping)" + "discrete (sampling)"  by pnoise simulation? or, set pnoise sampling frequency twice larger than PSS? Thank you!

  • I got solution!!!

    pnoise -> option -> additonalParams "sampleratio=2"

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