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Simulators >> Circuit Simulators >> Cadence Varactor's Simulation
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Message started by pcardoso73 on May 6^th, 2011, 2:32am

Title: Cadence Varactor's Simulation
Post by pcardoso73 on May 6^th, 2011, 2:32am

Dear all,

I would like to obtain the c-v and Q curves for a varactor. How can I do this ?

Best regards,
Pedro

Title: Re: Cadence Varactor's Simulation
Post by Ken Kundert on May 6^th, 2011, 8:54am

Take a look at http://www.designers-guide.org/Modeling/varactors.pdf. Listing 2 shows how to plot C versus V.

-Ken

Title: Re: Cadence Varactor's Simulation
Post by pcardoso73 on May 6^th, 2011, 1:46pm

Thanks a lot Ken. You are the master, so I am very grateful for you to answer this small question.
Well the thing was a bit the other way around, I was reading your document, and I thought that would be a good idea to plot those curves to the technology I am using (130 nm IBM). So my doubt is how to accurate simulate it ? I just did an AC analysis, and got current and capacitance. The rest was done in Matlab.

Another completely different question about Spectre. I am simulating a Crystal VCO on the tree inversion regions. As the BJT has much better behavior than the MOS relating to 1/f noise, I thought that it should be equivalent to weak inversion in MOS (exponential law as well). Simulating this in spectre gives a much better jitter and phase noise in the strong inversion. How can this be explained ? Just the extra amount of power spent justifies this.

I appreciate a lot that you have taken a bit of your time to answer to my post.

Thanks a lot.
Best regards,
Pedro

Title: Re: Cadence Varactor's Simulation
Post by purplewolf on May 21^st, 2011, 2:05pm

This might be inetresting

http://www.cadence.com/Community/forums/t/18829.aspx