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Simulators >> RF Simulators >> Problem in SC filter simulation
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Message started by shyboy on Jan 4^th, 2005, 8:37pm

Title: Problem in SC filter simulation
Post by shyboy on Jan 4^th, 2005, 8:37pm

Hi all,

I was trying to simulate an SC lowpass filter using spectre and I found that the output is very small, almost zero...So i guess i didn't give the correct input signal...
The input i used was a dc voltage source with dc level 1V and a PAC of 1V...Can anyone tell me whether this input is correctly set? If not, how should I set it?

Thanks~~

shyboy

Title: Re: Problem in SC filter simulation
Post by Andrew Beckett on Jan 4^th, 2005, 9:47pm

Well, without knowing what analyses you ran, it's hard to know...

Andrew.

Title: Re: Problem in SC filter simulation
Post by shyboy on Jan 4^th, 2005, 10:00pm

Hi, Andrew,

Thanks for your reply...I am new to cadence, so i may be asking silly questions...Is it true that, to simulate an SC filter using Spectre, I need to run a PSS analysis followed by a PAC analysis? Can I simply use just an AC analysis?

shyboy

Title: Re: Problem in SC filter simulation
Post by Frank Wiedmann on Jan 4^th, 2005, 11:37pm

Yes, you need to run a PSS analysis followed by a PAC analysis. No, you cannot simply use just an AC analysis. Have you already read http://www.designers-guide.com/Analysis/sc-filters.pdf ?

Title: Re: Problem in SC filter simulation
Post by shyboy on Jan 5^th, 2005, 6:25pm

yes, i did read that paper, but i don't quite understand it...Could you kindly clarify some of my doubts?

1. Vin: if i set the type to dc, how can i specify the frequncy, amplitude, etc.? And where can i find the "alter" statement?

2. pss analysis: What are fundamental tones and beat frequency and what is the correct manner to specify them? And where can i specify the maxacfreq? Also what are the parameters in Options that are normally specified during SC filter simulation?

3. pac analysis: what effect does maxsideband have on the sim result? The paper mainly talked about the effect of maxsideband in the noise analysis, i think...

Sorry for so many questions...BTW, i am a student struggling with a design project, and i don't have much background on this project...So any help from you guys will be appreciated...

Title: Re: Problem in SC filter simulation
Post by Andrew Beckett on Jan 11^th, 2005, 4:22pm

You could always read the documentation, or do you want us to do that for you as well?

Sorry for the cutting remark, but there is some fairly decent documentation for SpectreRF which would get you most of the way there.

Andrew.