Hi!
I simulate phase noise from LO through mixer with PSS+Pnoise. All blocks are implemmented with veriloga. One mixer input is connected to the DC signal, another to LO. With this setup I get the correct results of the phase noise at the mixer output. The problem comes when I connect low pass filter (which is modeled with laplace function) between DC signal and mixer. The phase noise at the mixer output drops down proportionally to the filter cut-off frequency, i.e. the higher the frequency, the lower phse noise I get. Same order of the filter implemmented as a RC chain gives the correct result.
Any clues where to start digging into this problem?