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How to reduce/eliminate PSS convergence errors?

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iVenky

iVenky

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Hi,

I am running PSS on Cadence Virtuoso for a wide-range Quadrature VCO. I am facing convergence issues sometimes. Sometimes it works. Do you know the reason behind these convergence issues and how to reduce/solve those?
 

* Some simulators insist that there be at least one 0V ground icon in your schematic.'

* Sometimes it helps to add a high-ohm resistor, at any node that the simulator might have trouble with. Tie it to a supply rail, or 0V ground.

* Capacitors and inductors should have a low-ohm resistor inline, to ensure the simulator can calculate a time constant for them, regardless of neighboring components.
 

iVenky said:
I am running PSS on Cadence Virtuoso for a wide-range Quadrature VCO.
I am facing convergence issues sometimes.
Sometimes it works.
Do you know the reason behind these convergence issues and how to reduce/solve those?
Click to expand...
Show me log file.

Can your QVCO satisfy oscillation condition surely ?
Did you confirm initial transient results ?

https://www.edaboard.com/threads/346180/#6
 
Last edited:

PSS requires that you truly have a stable and on-period
solution. If (for example) your tune voltage is still creeping,
is that then true? Maybe the trouble lies with your initial
conditions.
 

Is it possible for the oscillator to oscillate in transient sim but not in pss sim? It's oscillating in transient sim and I have given enough tstab for the pss sim.

- - - Updated - - -

pancho_hideboo said:
Show me log file.

Can your QVCO satisfy oscillation condition surely ?
Did you confirm initial transient results ?

https://www.edaboard.com/threads/346180/#6
Click to expand...

I will include the log file when I face an error once again. Thanks for your help!
 

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