Control Voltage vs Frequency [VCO]

[w101nnd]

Hi,

I am trying to plot the control voltage vs frequency in cadence for
vco.
any sugesstions as to which anaylsis do i have to do.

Thanks,

ND

 

[Andrew Beckett]

On Tue, 28 Jun 2005 19:10:28 -0500, n_dalia23@yahoo-dot-com.no-spam.invalid
(w101nnd) wrote:

Hi,

I am trying to plot the control voltage vs frequency in cadence for
vco.
any sugesstions as to which anaylsis do i have to do.

Thanks,

ND

Two approaches you could take - one is to use PSS in oscillator mode, and
sweep the control voltage. Then plot the "harmonic frequency" from the
results->direct plot->main form->pss and you'll get the oscillator frequency
versus the control frequency.

Alternatively, sweep the control voltage slowly, and connect the freq_meter
component from ahdlLib to the output of your circuit - then you can plot the
instantanous frequency (accurately, because it forces a timepoint at the
transition point you choose).

Or you can use the calculator function described in sourcelink solution
11015938.

Regards,

Andrew.

 

[Michael Ritzert]

w101nnd wrote:

I am trying to plot the control voltage vs frequency in cadence for
vco.
any sugesstions as to which anaylsis do i have to do.

We're running a transient analysis for some time, then remove the
intialization phase from the waveform. On the result you can then use
the freq() function.
The resulting term looks like so (simplified): freq(clip("/Q",50n,75n))
You can now use a parametric analysis to sweep the control voltage.

Michael