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- 7th February 2007, 05:05 #1
## 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

- 7th February 2007, 09:13 #2

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## s parameter to rlc model

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---

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- 7th February 2007, 09:13

- 7th February 2007, 23:18 #3

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## s-parameter to rlc model

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.

- 7th February 2007, 23:18

- 8th February 2007, 00:04 #4

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## calculating rlc 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 !!

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- 8th February 2007, 00:04

- 8th February 2007, 23:43 #5
## fitting s-parameters into rlc

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

- 9th February 2007, 06:18 #6

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## r l c equivalent fitting

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---

- 9th February 2007, 21:14 #7
## s-parameters rlc

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

- 11th March 2010, 14:11 #8

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## Re: S-parameters to RLC

exactly !!

broadspice do great convert to RLC from S

it is wonderful !!!

- 10th June 2010, 07:10 #9

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## Re: S-parameters to RLC

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.

- 28th June 2010, 16:26 #10

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## Re: S-parameters to RLC

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

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

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