Hi,

Simulation set-up:       (A)  gnd -- res -- sw -----              (B)  gnd -- res -- sw -------- sw -- res -- gnd
                                                        (ck)     |                                       (ck)     |    (ckb)
                                                                 cap                                              cap
                                                                   |                                                  |
                                                                 gnd                                              gnd
res = 500 Ohms (noise turned on)
sw = verilog-A model, noiseless
cap = 300f

For (A) and (B), I turned on the "trans noise" option in ADE and set noisefmax to 10G, and then ran a 10u transient sim. I then used the "rms" function in Calculator on the voltage across the cap.

For (A), the rms voltage is about 108uVrms, close to the theoretical value of 117uVrms ( sqrt(kT/C) of 1pF cap is 64uVrms ). For (B), I got the same number!     I was expecting sqrt(2) * 117 uVrms, since there are 2 clock phases, 2 different resistors, and hence no correlation on the 2 noise generators from res.

Can I use the rms function this way to compute the sampled kT/C noise, or .... what's really the problem?

Daffy