Lumped element model and circuit fitting

[Supaswing]

Lumped element model

Sorry I am not a electrical engineer and I cant find help around me to help me on this problem.
Can someone explain me the basics of circuit fitting. I want the frequency independant lumped values of a circuit.
I determined a circuit with unkowns parameters (C1-Cn,L1-Lm,R1-Rp,etc..):

1. How do resolve it and how should find the good parameters? Do I need a crcuit simulator or can I do it easily in Matlab for example?
2. Do I need V-I meausrement, R+iX, or S-parameters or both?

Thank you in advance
David

 

[flatulent]

Re: Lumped element model

For passive circuits this is called synthesis. There are books on the subject. You have your impedance or transfer functions in the form of polynomials and there are standard ways to get the circuit component values.


For transistors there are equivalent circuits that have been show to work well. Their values are based on measurement of the transistor performance at different frequencies.

 

[Syukri]

Re: Lumped element model

Circuit simulator is easier to use than MAtlab if u have an electrical basis. The parameters is already determine thus make it easy to be analyse.

Matlab also can be used, but to get a good analysis, other than simulating the equation of the circuit, all different aspect like noise need to be calculated also.

 

[Supaswing]

Re: Lumped element model : Equivalent circuit

Thank you for answers but i am not sure about the first step which is the determine the parameters of the (passive) circuit before simulating it.
I still dont know :
1. I have my impedance Z11 or my S11 data (complex), first I a do a polynomial fitting But how do you do when you complex data.

2. I build my equivalent circuit and I extract the polynomial form. With active circuit its easy because of the Zin and Zout almost ideal and you build the transfer function Uo/Ui with blocks like (1/ｊｗｃ、１/（１+ｊｗL),etc..) but I dont know about passive circuit.

To simulate the circuit, I think its the easiest part if you have a linear system with coefficent determined.