Hello to the community,
I have designed a 14 GHz VCO on schematic view that I usually simulate using harmonic balance (HB) analysis and everything works fine for the extraction of its typical figures of merit.
My goal is to study the effect of various small perturbations, with different frequencies, on different nodes of the circuit. Say the perturbations I want to inject are in the MHz range, my hope is that I can see spurs generated in the output spectrum of the VCO that would be there either because of FM or AM.
I use a sinusoidal voltage source to generate these perturbations but unfortunately, HB analysis doesn't work on an autonomous circuit when a voltage source is present on the design so I can't simulate my circuit. I also tried using ' tran ' analysis but the VCO won't start up on its own when I'm not using HB. Other analysis types for periodic circuits require an input fundamental frequency but I effectively have two in my circuit : the 14 GHz signal generated by the VCO itself, and the MHz signal I inject on different nodes.
Has anyone been in this situation before ? If anyone could give me advice on how to simulate such an effect I would be grateful.
Thank you.
Youssef
