Plotting osillation frequency vs. current

Hello,
I have 4 stage current-controlled ring oscillator. I need to plot
oscillation frequency vs. control current plot. Control current - dc
current, it needs to be varied using parametric analysis. The frequency
of oscillators depends on the control current. Therefore, it is not
defined anywhere.
Can anyone help me.
Thanks,
Vitaliy

 

What's not defined anywhere?

You can measure the frequency of the oscillators several ways:

1. Using PSS analysis in oscillator mode, and then sweeping the control current.
You can then plot "harmonic frequency" on the PSS direct plot form, and it
will be versus the control frequency.
2. You could use the "frequency" function in the calculator, which will give
average frequency (you might want to use clip so you can miss out the
startup condition).
3. You could use the freq_meter component in ahdlLib to measure the
instantaneous frequency during the transient, and then do a sweep
4. Recently (may be in IC5141 USR3?) a "freq" function was added in the
calculator to give instantaneous frequency.
5. In older versions you could use the SKILL code in my solution 11015938
on http://sourcelink.cadence.com to calculate instantaneous frequency.

Regards,

Andrew.