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vp1953

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Cadence ADE vs Matlab
Feb 24^th, 2011, 3:44pm

I am wondering if it is possible to do loop filter and open loop gain phase plots for PLL's using Cadence ADE. Normally I use Matlab for this and several people in this forum have alluded to the fact that it is possible to do the analysis in Cadence ADE itself.

I am specifically interesting in knowing how to use laplace domain models for the oscillator, phase detector etc in Cadence ADE.

Thank you in advance.

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sheldon Community Fellow Offline Posts: 751	Re: Cadence ADE vs Matlab Reply #1 - Feb 24^th, 2011, 4:33pm vp1953, You could try laplace functions in Verilog-A or look at spectre -h svcvs. Best Regards, Sheldon
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vp1953 Senior Member Offline Posts: 172	Re: Cadence ADE vs Matlab Reply #2 - Feb 25^th, 2011, 2:48pm Hi Sheldon, Many thanks! For laplace functions in verilog-a, what analysis would be recommended for gain/phase plots. I am just reading up on this and there seems to be an opinion that small signal ac analysis is not supported for laplace functions in veriloga.
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sheldon

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Re: Cadence ADE vs Matlab
Reply #3 - Feb 25^th, 2011, 9:26pm

vp1953,

I was a little bit lazy and used an svcvs source and ran a quick
test, as you can see the laplace function does work with ac analysis.
I have not tried the Verilog-A laplace but it should work also. I saw
the comment also and it was not directly related to the laplace
function. The comment was related to using the z-transform
capability of Verilog-A.

Best Regards,

Sheldon

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vp1953

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Re: Cadence ADE vs Matlab
Reply #4 - Feb 26^th, 2011, 8:58am

Hi Sheldon,

Thank you very much again!!

I tried small signal ac analysis with the low pass filter available in the ahdl library and it does not seem to work with ac analysis; the filter however is a time domain model and does not have any laplace functions in it.

I have one other question -

I am currently reading up on the phase domain model of the PLL available at

http://www.designers-guide.org/Analysis/PLLnoise.pdf

Can this model be used to run small signal ac analysis to get gain/phase plots?

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