[ibis-macro] FW: a s2p example for output impedance and reflection

  • From: <fangyi_rao@xxxxxxxxxxx>
  • To: <ibis-macro@xxxxxxxxxxxxx>
  • Date: Tue, 14 Dec 2010 14:09:04 -0700

Forwarding my analytical analysis shown at today's meeting.

From: RAO,FANGYI (A-USA,ex1)
Sent: Monday, December 13, 2010 4:52 PM
To: Muranyi, Arpad; Walter Katz; Scott McMorrow; Bob Ross; Todd Westerhoff; 
Dmitriev-Zdorov, Vladimir; BIERNACKI,RADEK (A-Sonoma,ex1)
Cc: RAO,FANGYI (A-USA,ex1)
Subject: a s2p example for output impedance and reflection

Hi, AMI colleagues;

Following the discussion in the last ATM meeting about S-parameter file in AMI 
models, I think it might be helpful to use a simplified s2p example to 
facilitate the discussion. Since I dropped out from the meeting before it 
ended, I probably miss the conclusion you guys reached at the end and my 
analysis here may not be relevant.

In the circuit below the reference impedance of the s2p is Z0 and the impedance 
of port 2 termination is Z.
[cid:image003.jpg@01CB9AE6.1F63A250]
The circuit equations are

[cid:image012.png@01CB9AE4.C5C11EE0]

Solve for V2 we get

[cid:image014.png@01CB9AE4.C5C11EE0]

So V2 depends on port 2 impedance Z. When Z=Z0, S22 and S12 disappear in the 
solution.

[cid:image016.png@01CB9AE4.C5C11EE0]

Regards,
Fangyi

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