[SI-LIST] Re: crystal oscillator spice simulation
- From: "Mike Monett" <vya-4l0j@xxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Fri, 06 Oct 2006 10:51:02 -0400
Hello Canes,
Sorry forthe dupe. I sent the original the wrong address.
>Hi all,
> I'm involved in characterizing crystal oscillator cell (available
> as netlist). I thought of putting the equivalent circuit of
> crystal and package parasitics and simulate it, for finding the
> frequency deviations in all process corners. I'd used some kick
> start for inductor by initializing it with some current. Does it
> represent the realtime situations. Or should we have to insert
> noise into the oscillator, which mimics actual scenario.
> Also I want to know whats the challenge involved in characterizing
> such scenarios. I mean, what we have to look in such
> characterizations. Why people say it takes much time to simulate,
> convergence issues etc. Are there any procedures for
> characterizing the crystal oscillator cells, which tells what and
> how to analyse.
> I just pasted my spice file. Please look into and tell where I may
> be making mistakes or what more analyses I should do to make it
> full fledged analysis.
>Regards
>Canes
Crystal oscillators are difficult to analyze in SPICE due to the
high tank Q, which requires a long settling time. But the analysis
is needed to prevent overdriving the crystal or operating the
oscillator in the saturation region.
A link below shows a simple method to set the initial current in the
inductor to the desired power level, and how to adjust the feedback
so the oscillator maintains that level. This method speeds the
analysis by a factor of perhaps 4,000 or more.
It uses a waveform analysis feature that is provided in Spectrum
Software's Microcap 8 SPICE. You can download a free demo at the
link provided in the paper.
If you have any questions, please post them here so others can see.
Regards,
Mike Monett
Antiviral, Antibacterial Silver Solution:
http://silversol.freewebpage.org/index.htm
SPICE Analysis of Crystal Oscillators:
http://silversol.freewebpage.org/spice/xtal/clapp.htm
Noise-Rejecting Wideband Sampler:
http://www3.sympatico.ca/add.automation/sampler/intro.htm
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