I tried to simulate the KT/C noise by PSS+PNOISE analysis as explained in "Simulating switched-capacitor filters with SpectreRF" (http://www.designers-guide.org/Analysis/sc-filters.pdf).
I used an ideal switch (relay) controlled by square wave clock signal series with a 770ohm resistor, dc input and a 10fF sampling capacitor as seen in attached netlist. The sampling clock was 7GHz and the S/H bandwidth around 20GHz, I lunched a shooting PSS with beat frequency of 7GHz with 100 harmonics and specified 770GHz for maxacfreq (as recommended in article 10xfc+Nmsbxfc). My first interesting range of noise folding in PNOISE analysis was up to 100 sidebands and that is why I choosed the above value for maxacfreq. The PNOISE was defined in range of 0 to 3.5GHz (half of the sampling clock) and I used time domain option and integrate the output noise from 0 to 3.5GHz. The result was 621.2425uV for 100 sideband, while it was 621.8437uV for 500 and 1000 sidebands of pnoise simulation (Just to note that I increased maxacfreq when I increase Nmsb). It seems that the stabilized value is around the 621uV while it has -3.5% error with the calculated analytical value of 643u (sqrt(KT/C)) and noise analysis of shorted switch ideal RC filter sim result. Is there anything wrong in my test bench or simulation setting, cause in the article the error is achieved less than 1% by increasing the number of sidebands?

Thanks for your reply, I am interested in sampled data noise analysis at specific time point and I think it is the same time averaged noise by time domain feature of PNOISE. It is consistent with the setting of LISTING1 (page 3) and first paragraph of page 13 in reference. Meanwhile integrating the power of noise output from pnoise analysis with 'source' feature of noise type gives 325uV stabilized value.

I suggest that you use pnoise jitter analysis. It is equivalent to pnoise tdnoise but allows you to specify the sampling instant by giving a threshold level for the signal (see also http://www.designers-guide.org/Forum/YaBB.pl?num=1224609785).

I also recommend that you use the fullspectrum option of the pnoise analysis, which is available in APS mode (see http://support.cadence.com/wps/mypoc/cos?uri=deeplinkmin:DocumentViewer;src=pubs...). It takes into account all sidebands for white noise, so you only need to specify the number of sidebands required to cover colored noise sources (usually 1/f-noise). If you use the fullspectrum option, be sure to set the value of the maxacfreq parameter of the pss analysis large enough (because it cannot be verified automatically against the specified number of sidebands in the pnoise analysis).