SpectreRF pnoise simulation: sampled output noise of a chopping amplifer

luminedinburgh

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?

david_reg

there is a parameter which can change the sample frequency in pnoise sampled noise analysis
20      sampleratio=1     The ratio between sampled frequency and fund frequency (sampled frequency/fund
                          frequency)..

luminedinburgh

david_reg 发表于 2021-10-27 08:56
there is a parameter which can change the sample frequency in pnoise sampled noise analysis
20      ...

It works, thank you!