PSRR of a VCO using spectre-RF?

Is there a way to simulate the PSRR of a VCO using spectre-RF? I want
to plot the delta-frequency of the VCO vs. the input frequency of a
sinusoidal tone on the power supply. It seems PXF can give me the
delta-voltage of the VCO output vs. the frequency of the tone on the
power supply, but not the delta-frequency. The true brute-force method
would be to run several transient sims of the VCO each with a different
frequency tone on the supply (e.g. 1MHz - but this would take 1us of
sim time to see one cycle of the tone! and the VCO is at 5GHz.)
Any ideas? thanks.

 

I think you could probably do this using the "modulated" option on the PXF
analysis introduced in IC5033 and later.

This allows you to look at the AM and PM component of the transfer function.

I _think_ that ought to do it, but not 100% sure without thinking about it a
bit more...

Andrew.