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How to simulate systems including multi-frequency signals varied greatly? (Read 4708 times)
flz
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How to simulate systems including multi-frequency signals varied greatly?
Jun 28th, 2009, 7:47pm
 
I am working on simulating a system of three frequncies which are about 5Hz, 5kHz, 500kHz. I found it is really hard because it usually cost too much time to get reliable results, and usually can not  converge. Can anyone give me some advices on how to simulate such systems efficiently? especially, advices on simulating strategies.  :-[
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pancho_hideboo
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Re: How to simulate systems including multi-frequency signals varied greatly?
Reply #1 - Jun 29th, 2009, 6:49am
 
flz wrote on Jun 28th, 2009, 7:47pm:
I am working on simulating a system of three frequncies which are about 5Hz, 5kHz, 500kHz. I found it is really hard because it usually cost too much time to get reliable results, and usually can not  converge. Can anyone give me some advices on how to simulate such systems efficiently? especially, advices on simulating strategies.  :-[

Your question is too lack of information, so no one can answer.

What waveform do you use for 5Hz, 5kHz, 500kHz signals ?
These are all rectangular ?

5Hz and 5kHz are sinusoidal signals ?
500kHz is clock of SCF ?

How do these three signals behave in your system ?

What is your system's application ?

Which is your interest in simulation, transient behavior or steady state behavior ?

Which is your modeling for simulation, signal flow system or energy conservative system ?

What simulator engine do you use ?
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« Last Edit: Jun 29th, 2009, 7:57am by pancho_hideboo »  
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flz
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Re: How to simulate systems including multi-frequency signals varied greatly?
Reply #2 - Jul 2nd, 2009, 2:29am
 
Thanks for pancho_hideboo's reminding.I am sorry I have not described the problem clearly.
The systems I am working on are most micro-electromechanical systems composed of mechanical stuctures and analog circuits. The  structures and the circuit components are modeled with Verilog-a HDL in system level, than they can be simulated by the same analog simulator.The systems built up usually are mixed-model systems, including both signal models and conservative models.
Usually, there are three kind of signals in the system, the sensitive signal from out environment(5Hz), drive signal(5kHz), and the carry wave(500kHz), and all of them are simplely taken as sinusoidal. All the sources such as the drive signals are all given directly by ideal models in order to reduce the compution.
My problem is that the frequncise of sensitive signals and the carry waves differ so greatly that it takes too long time to get a steady result(run several periods ), are there any simulating strategies that can simpfy the simulation for such systems in pure circuits simulation field? I hope I can get some tips from your experience.

ps: Usually the equations of the structures part are much more than the circuits part, and there are connected by coupled models, such as electrode plate, and we can modify the simulator engine we used.

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pancho_hideboo
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Re: How to simulate systems including multi-frequency signals varied greatly?
Reply #3 - Jul 2nd, 2009, 6:23am
 
Use correct terminologies.

Still I can't know how degree you know modeling and various simulator as well as your signal processing scheme.

flz wrote on Jul 2nd, 2009, 2:29am:
The structures and the circuit components are modeled with Verilog-a HDL in system level,
than they can be simulated by the same analog simulator.
"than?" Is it Verilog-A ?
What is same as ?

flz wrote on Jul 2nd, 2009, 2:29am:
and the carry wave(500kHz), and all of them are simplely taken as sinusoidal.
What is "carry wave" ? Is it "Carrier Wave" ?

All three signals are input signals ?
How do they interact each other ?
How much of higher order harmonics do you expect for each tone, 5Hz, 5kHz and 500kHz ?

flz wrote on Jul 2nd, 2009, 2:29am:
are there any simulating strategies that can simpfy the simulation for such systems in pure circuits simulation field?

If there is no hidden state in models, you can use Multitone Steady State Analyis such as QPSS or Envelope Analysis.
Here there are many possibilities in how to apply QPSS or Envelope Analysis for your target system.
But I can't give you clear suggestion since your descriptions or explanations about your targets are still very very poor.

flz wrote on Jul 2nd, 2009, 2:29am:
ps: Usually the equations of the structures part are much more than the circuits part,
and there are connected by coupled models, such as electrode plate,
and we can modify the simulator engine we used.
I can't understand what you mean ?
Do you make original simulator ?
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« Last Edit: Jul 3rd, 2009, 6:14am by pancho_hideboo »  
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