pss analysis doesn't converge

[us1710]

hi , i have done PSS analysis for VCO . but it is giving error messege that " pss analysis doesn't converge . what could be the error ? i hv checked the ckt for different tstab , but it does not work. should i increase maxperiod?

 

[tfwee]

Before you run the PSS, maybe you would like to run a transient analysis to check how long does it take for your oscillator to start oscillating. From this, you can key in the tstab. If the same problem occured, maybe you should change the tolerance options under simulator options to a finer resolution. This may help in your convergence issue.

 

[GDF]

Check all the warning from the simulator.
Don't ignore it.

 

[rjshmadala]

Here i have uploaded a file on how to perform PSS and Phase noise analysis using candence tools. hope it will help to u

 

[sunking]

simple your circuit and try

 

[zenisle]

maybe you can set the init nodes voltage.

 

[pi331133]

For PSS the guessed beat frequency should closed to the real oscillating frequency. Also need a long initial transient time.

 

[us1710]

thanx rjshmadala , i did not specify the max step parameter ,now it is ok.

 

[eejli]

How much max time step you put there compared to your oscillation period?

Thanks