How can I extract resistance,capacitance,and inductance from S-parameters?

Hi Guys...
How can I extract resistance,capacitance,and inductance from S-parameters..
I keep finding these papers and they all conatain this phrase "the S-parameters were fitted into an RLC circuit model"...I want to do the same thing to get the values of RLC of a structure modeled in HFSS..
Please help

Thank You

Hello nghalion,

The attached document on TESTING S-PARAMETERS FOR TYPICAL PASSIVE CIRCUITS (3TestSpars4Circuits.pdf) discusses about this issue...

You can do
Effective Inductance (nH) of a Series RL network
L(nH)=1.0E9 * imag( 1 / Y11) / ( 2*PI* FREQ )
Series Inductance (nH) between any pair of ports assuming a PI-model
L(nH)=-1.0E9 * imag( 1 / Y21) / ( 2*PI* FREQ )

Effective Capacitance (pF) of a Series RC network
C(pF)=-1.0E12 / ( 2*PI* FREQ * imag( 1 / Y11) )
Series capacitance (pF) between any pair of ports assuming a PI-model
C(pF)=1.0E12 / ( 2*PI* FREQ * imag( 1 / Y21) )


---manju---

There are software packages that fit RLC equivalent circuits to S-parameters, such as http://www.emwonder.com/.

Microwave Office and Sonnet will also. I believe Ansoft sells a seperate package to do this.

Using good judgement you can come up with an equivalent RLC circuit by hand and run an optimizer to fit it to the s-parameters.

the BoardSpice from Sigrity can fit very excellent results , then the extract RLC model can run under HSpice , try it
But , do precisious measurement is a the first and the most important key Step !

I thank You all for ur replies..but I'm still a bit confused here..

Exactly which parameters should I plot in HFSS (S, Y, or Z) and in what function (im, re, mag, dB..etc.) and at which frequencies should I apply the equations provided by Manjunatha_hv

I provided the S-parameters (dB) earlier, and here is a pic of the project in HFSS..

Thanx in advance

Hello nghalion,


Is this capacitive MEMS Switch or CPW structure ?...
upload the DXF file with dielectric layer details I will try to help using may be Microwave Office or Sonnet ( if it is planar structure)...

You need to plot Im of Y parameters to use with the mentioned equations....


---manju---

Hi manju,

It's a capacitive shunt switch but this is not my original project. I'm working on this one for it's simplicity. Unfortunately I don't know how to to create a DXF file of it because the model was made in HFSS and no export to DXF option is available. I heard that it is possible to fit the S-parameters into RLC in MATLAB. I don't know if someone has a code for the operation but anyways, thanks alot for your help..

nghalion

Added after 3 minutes:

Forgot to say that it's a capacitive Mems shunt switch positioned on top of a CPW..
And I must find S-parameters in both Up-state and Down-state and the equivalent circuit model for each case..

Thanks

exactly !
broadspice do great convert to RLC from S

it is wonderful !

Hi there,

I am facing similar problem RLC extraction from S-Parameter. I understand that the inductance of a simple RF MEMS switch is abt 7pH for a 80um wide armature over a 60um/100um/60um CPW. However when I extract it using Sonnet with the effective inductance formula, the value is about 30pH.

Can anyone please help to enlighten me on this issue?

Thanks in advance.

you can see also here to find Y Z matrices and S-->Z

http://www.uwaverf.altervista.org/in...d=48&Itemid=53