Re: VCO pulling
There are names for the two different effects!
VCO Pulling: Means load variation effect on VCO phase/frequency performance
VCO Pushing: Means effects on supply and control voltages
If you inject a small tone which harmonic related to the natural frequency on the supplies (VDD,VSS, Substrate) you will get a phase reaction. If the small tone is coupled with the VCO output (synthesizer, PA) the frequency will shift.
Simulation of this effect is little tricky. Phase pertubation could be best seen by simulating two VCOs. One impacted, the other not. Make a phase difference plot. If the frequency shift should be observed you have to search for the coupling element. In most cases the substrate or supply. Simulate with and without the coupling but be careful not to change bias conditions. So only inductance change or zero DC current resistive substrate path are allowed. Otherwise the result is not true. You have to search for some kHz at some GHz!!!