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madmozart

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Difference between frequency/time domain simulator
Aug 08^th, 2006, 8:12am

Hi everyone:

What's the essential difference between frequency and time domain simulators?
What's the substantial differnece between their performance?
I was asked this question in an interview with a professor.
I guess the answer is not as trivial as it seems to be.
Could anyone give any comment on this?
Those EDA experts are more than welcomed to add anything on it.
Thanks a lot!

Steve

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byang

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Re: Difference between frequency/time domain simul
Reply #1 - Aug 8^th, 2006, 9:07pm

Hi, Steve,

If you have access to IEEE digital library, you can read a couple of my DAC papers on a method called "Multi-Interval Chebyshev" method. That is a high-order time-domain method for combining the advantages of time-domain and frequency-domain methods. You'll understand the difference between time-domain and frequency-domain methods if you can take a look at the paper.

Baolin

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David Lee

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Re: Difference between frequency/time domain simul
Reply #2 - Aug 8^th, 2006, 9:38pm

Steady state analysis methods include time-domain shooting, multi-tone frequency-domain harmonic balance, multi-tone mixed-frequency-time methods. A similar set exists for envelope analysis, and for noise analysis.
Have a look at:
Mayaram, K. Lee, D.C. Moinian, S. Rich, D.A. Roychowdhury, J.
"Computer-aided circuit analysis tools for RFIC simulation:algorithms, features, and limitations",
IEEE Transactions on Circuits and Systems II, Volume 47, No 4, Apr 2000, Page(s): 274-286
http://laoo.dtc.umn.edu/~jr/research/PDFs/2000-TCAS2-Mayaram-Lee-Moinian-Rich-Ro...

and Ken Kundert's "Introduction to RF Simulation and its Application,"
http://www.designers-guide.org/Analysis/rf-sim.pdf

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« Last Edit: Aug 9^th, 2006, 10:19am by David Lee »

- David

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madmozart

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Re: Difference between frequency/time domain simul
Reply #3 - Aug 10^th, 2006, 8:26am

Hi Baolin & David:

Thanks for your note. I found them very informative.
Basically I understand how HB and time-domain (finite-difference) simulators work.
HB is trying to use sinusoidals as base function to construct the signal specturm, but due to nonlinearity in the circuit, it gotta do FFT/IFFT.
In purely time-domain simulators, we are using different algorithms to fit the first order derivative, am I right?
Both approaches use Newton method to linearize the nonlinear equations.
But does either one have any edge on converge in nature than the other one? If not, why?
And it seems like no purely time-domain method can solve the modulation problem, is that true?
Thanks a lot for your help.

Steve

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