Hello,

I am currently simulating the phase noise of a VCO wih cadence spectreRF AA simulation tool. I have read the help files of AA concerning the phase noise simulation of oscillators and cadence's whitepaper "oscnoise.pdf" available on the net.

The problem which I am having is the following:

What exactly is the meaning of a "sideband" (referred by the "maxsidebands" field located in the PNOISE form)?

In the help file,a sideband Ki is defined by the following equation:
f(noisesource)= f(out)+ Ki*fund(pss)
Does this mean that a sideband defines the noise frequencies which are used in the computation of the PN around the desired harmonic of the output?

According to the help files, one should set the maxsideband field to 0 (at least for PN of oscillators). Shouldn't one set the maxsidebands field to a large number as to evaluate the PN due to all sidebands (whatever they are)?

My problem is that my results improve by 40dBs when I shitch from a "maxsidebands" of 0 to a "maxsidebands" of 1 ?
I would like to know which of the the results is the real one.

Any help will be appreciated.
Regards
-Frank

P.S This is msg is posted for the 2nd time, since I can't seem to find the original posting. So if it is doubled somewhhere in this forum and I just can't seem to find it, please ignore this post.