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What does simulator do to solve a circuit?  RF Cafe Forums

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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
Top Profile
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.
Top Profile
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.
Top
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!
Top
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.
Top
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
Top
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
Top
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



