I use PSS to simulate VCO. A voltage pulse with amplitude of 0.1V is added to stimuli the circuit and the circuit can oscillate. I just wonder whether this simulation really represent the circuit's performance since 0.1V is large compared to the noise.
And another question is that how to reduce the simulation time? With this method, it takes me a few minutes to finish the simulation.
Any good tutorials about VCO simulation in SpectreRF?
Now I am thinking manye that my oscillator doesn't start up to oscillate at all. It is just a simpel PMOS cross-couple structure on .18um CMOS. The tail current is about 10mA. Isn't this current enough to oscillate?
try to check the resistance of ur resonator , and design the negative gm of the cross coupled pair , to be 2 to three times of the resistence of he resonator