Thomas,

Your settings imply that you have a large signal input (for the 500Hz signal). You probably don't need that unless this signal is large enough to cause distortion, and you want to analyses the intermodulation of the noise with that distorting input.

So, probably you just want to make the input signal a small signal (or DC for the purposes of noise analysis). This means your PSS will run faster, and also you then need as many harmonics/sidebands of the chop frequency as are likely to contribute noise. Also, the reference sideband would be 0, since the input and output frequencies are the same - there is no shift of the specified output sweep frequency needed in order to get to the input frequency.

If you've not done so, you might want to read http://www.designers-guide.org/Analysis/sc-filters.pdf as much of what is said there would apply to a chopping amplifer.

Best Regards,

Andrew.