

What Does Simulator Do to Solve a Circuit?  RF Cafe Forums

rfseek Post subject: What does simulator do to solve a circuit?
Unread postPosted: Sun Apr 24, 2005 12:42 am Offline Lieutenant
Joined: Sun Apr 24, 2005 12:21 am Posts: 1 I would like
to have a knowhow of behind the scene working principle of simulators
for the various types of solutions?
1. What does a simulator
say, ADS, do for S parameter simulation or in other words how does
it solve the circuit when u use lumped elements and when u use the
transmission lines?
2. What is the analysis procedure of
the simulator while performing an ac analysis and Harmonic balance?
3. In time domain solution what kind of equations are solved
by the simulator?
I would appreciate if somebody can explain
me these?
Thanks
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Qacer
Post subject: Unread postPosted: Tue Apr 26, 2005 9:29 pm
Offline Captain
Joined: Sat Apr 23, 2005 2:09 pm
Posts: 17 Location: Tampa, FL I don't have a clue, either.
I actually took a matrix computations class once and the professor
said that circuit simulators such as spice use it to solve problems.
It actually makes sense especially if you're dealing with the DC
stuff and zparameters. You can kinda see how the computer would
solve such a problem by using matrix analysis. I'm assuming that
other simulators do the same thing. Also, it was mentioned that
there are different numerical techniques for matrix computations
that one can use to speed up the calculation.
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AP Post subject: Unread postPosted: Mon May
16, 2005 1:00 pm
Qacer wrote: I don't have a clue, either.
I actually took a matrix computations class once and the professor
said that circuit simulators such as spice use it to solve problems.
It actually makes sense especially if you're dealing with the DC
stuff and zparameters. You can kinda see how the computer would
solve such a problem by using matrix analysis. I'm assuming that
other simulators do the same thing. Also, it was mentioned that
there are different numerical techniques for matrix computations
that one can use to speed up the calculation.
I"m pretty
sure ADS uses ABCD matrices for each element that it just multiplies
together  then converts to SParamters at the end.
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Guest Post subject: Circuit Simulators  How They
Work Unread postPosted: Tue May 17, 2005 11:53 am
An
excellent book on this topic is Applied Circuit Theory by P.R. Adby.
There is a reprint of this formerly outofprint book available
from Oscar Books (you can also search for it on www.bookfinder.com)
He covers both passive circuits ("ABCD" or "Chain Matrix" approach,
for example) and active circuits.
Good Luck!
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Guest Post subject: Unread postPosted: Wed May
18, 2005 11:47 am
I think that time domain simulation and
Frequency domain have quite different approach.
ABCD matrix
are for frequency domain steady state solutions.
Time domain
simulation as I remember use discretised differential equations
networks and very small step sizes to make time incremental simultation.
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guest Post subject: circuit sim Unread
postPosted: Sun May 22, 2005 4:16 am
this might help!
http://web.engr.oregonstate.edu/~karti/ece521.html
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Guest Post subject: Unread postPosted:
Sun May 29, 2005 12:40 pm
Anonymous wrote: I think that
time domain simulation and Frequency domain have quite different
approach.
ABCD matrix are for frequency domain steady state
solutions.
Time domain simulation as I remember use discretised
differential equations networks and very small step sizes to make
time incremental simultation.
I think this is somehow
a right answer
LLY
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Guest Post
subject: Unread postPosted: Tue May 31, 2005 3:09 pm
I agree with the time domain differential equation solver and then
conversion to sparameters for programs like ADS.
I remember
the Runge Kutta method taught in my ODE class and always wodnered
at the time who the heck would use such a thing!
Im sure
it's this or another more efficient numerical method to solve the
DFQs..... Processor power, throughput time and pipelining, is key
with these huge models!!!! :shock:
Posted 11/12/2012



