Hi everybody,

I read the Kundert paper on PSS/Pnoise but still like to ask for your help in some questions.

I am simulating a differential SC sampling circuit applying an OTA, which itself uses a SC-CMFB. Thus if running the transient analysis it takes some clock periods to be stable (until the CM output level is fixed). The DC-OP is not constant each cycle until it reaches its final value (though it works then considering settling time and error only).

1 Is it allowed to run a PSS over this? Or do I have to fix the circuit (e.g. by reading the final DC data of the trans first) before starting the PSS?

2 When doing the Pnoise then, can somebody tell me what spectrum of the output noise I am to expect? Now, it still looks like 1/f + thermal , but shouldn't it look periodically?

3 I am sampling frequencies up to 8MHz (if this matters) with 40 MSamples/s. What maximum sideband shall I use, and from where to where shall I integrate to get the noise power? Like 1Hz to fc/2 only?

Thanks a lot, I really appreciate your help!

Johannes.

Thanks a lot, chase! The tstab was exactly want I needed. Now it works as expected with me, I got the noise spectrum I wanted.

But it does not look like 1/f + white noise. I don't have flicker noise at all anymore, because it is folded up to the sampling frequency. I thought this is the case for all SH circuits, but maybe it's only with the certain switching scheme I looked up. I am doing a pipeline ADC gain stage with offset cancellation and two clocks - Don't worry about that and thanks for your help!
Johannes