Quote:The PAC linearizes the circuit about a periodically time-varying operating point.
Is that what you mean by the equation sin(phi)+delta_phi*cos(phi) with delta_phi being a small excursion from the operating point, Eugene?
Yes. It would be nice if one of the SpectreRF experts could confirm my claim.
You are not the first to be confused. If I don't use the tool for a few months I have to dig into the manual or e-mail someone. One of my complaints about the SpectreRF PAC, Pnoise, Pxf GUIs is that although the manual is very clear about sidebands, the GUI does not say which field is the input and which is the output. Thus, I am forced to waste time experimenting with simple circuits or searching for someone who remembers. Anyway, I believe that for PAC, the topmost frequency fields in the GUI are for the input range. The rest is output. For Pnoise and PXF, it is reversed. You must deal with sidebands when you have frequency translation. Since you are injecting a frequency perturbation, you are injecting at baseband. However, you are observing it at RF(i.e. passband). You have frequency translation. I duplicated Frank's observations by specifying a baseband range in the topmost fields and selecting the output range in the lower fields. I believe I used a -1 sideband but I'm not sure, I am not at my workstation. Frank included some netlist lines that answer that question. I believe the +1 side band gives similar results because a sinusoid has output at positive and negative frequencies.