QVCO pss could not convergent

[wccheng]

Dear all,

I design a QVCO and connect to the divider as loading. It could oscillate in the transient simulation. However, it could not convergent in the pss simulation. Could you teach me to fix this problem in order to run pss?

Thanks

wccheng

 

[BigBoss]

Because there are 2 fundemantal frequencies and PSS can not converge in standard setup.
HB can be more suitable for this circuit.
As I remember, Cadence has released a AN for this phenomena, if you find it somewhere, it will help you to determine the PSS setup..

 

[wccheng]

AN is stand for what?

Because there are 2 fundemantal frequencies and PSS can not converge in standard setup.
HB can be more suitable for this circuit.
As I remember, Cadence has released a AN for this phenomena, if you find it somewhere, it will help you to determine the PSS setup..

Added after 24 minutes:

On the other hand, my QVCO connects with all divider for the simulation. Will it increase the difficult in convergent?

 

[BigBoss]

AN is stand for what?
On the other hand, my QVCO connects with all divider for the simulation. Will it increase the difficult in convergent?

AN:Application Note

Of course, due to nature of PSS analysis, if there are 2 frequencies which are unknown ( in the case of Oscillator simulation) PSS wouldn't find the oscillation frequency because of existence of two frequencies at the same time.

PSS seeks oscillation frequency as unique one.When it finds two or more, creates convergence problems.