I am wondering about whether  power supply coupled with a large tone, which  will modulate VCO to cause large spur at VCO output, how can I simulate it? I try to use QPSS, but VCO frequency is autonomous, I don't know how to set it as one fund of simulation.

Daxigua,

    You might want to try semi-autonomous PSS analysis. It enables you
to include a driven signal with an autonomous signal. Semi-autonomous
analysis is a large signal analysis.

                                                             Best Regards,

                                                                Sheldon