[SI-LIST] Re: Return loss measurement on differential signals

  • From: "Arun kumar P N" <arun@xxxxxxxxxxxxxxxx>
  • To: "'Scott McMorrow'" <scott@xxxxxxxxxxxxx>
  • Date: Mon, 13 Apr 2009 19:52:11 +0530

Hi Scott,
 

Thanks for your info. Let me go through.

 

Regards,

Arun Kumar

 

From: Scott McMorrow [mailto:scott@xxxxxxxxxxxxx] 
Sent: Monday, April 13, 2009 7:50 PM
To: Arun kumar P N
Cc: 'steve weir'; si-list@xxxxxxxxxxxxx; anuj.singh@xxxxxxxxxxxx
Subject: Re: [SI-LIST] Re: Return loss measurement on differential signals

 

Arun

I suggest that you use the Agilent website as a resource.  There are many
papers on these subjects there.

regards,

Scott


Arun kumar P N wrote: 

Hi Steve,
 
Thanks for your reply.
 
Can you reply in details? and if you have docs please forward to me. I will
go through it.
 
Arun Kumar
 
-----Original Message-----
From: steve weir [mailto:weirsi@xxxxxxxxxx] 
Sent: Monday, April 13, 2009 7:36 PM
To: Arun kumar P N
Cc: si-list@xxxxxxxxxxxxx; anuj.singh@xxxxxxxxxxxx
Subject: Re: [SI-LIST] Return loss measurement on differential signals
 
For differential signals you need to do four port measurements.  The 
poor man's solution is to use baluns.  This adds error sources that need 
to be corrected and is limited to the linear range of the baluns.
 
Steve.
Arun kumar P N wrote:
  

Hi all,
 
 
I had gone through the details about return loss measurement and relation
between VSWR(Voltage standing wave ratio) & reflection coefficient in
Google.
 
 
 
Return loss = -20log (Vr/Vt)
 
Where,
 
Vr- Amplitude of reflected wave
 
Vt- Amplitude of Transmitted wave
 
 
 
ñ  magnitude of   Ã 
 
ñ = | Ã | .
 
 
 
Relation between VSWR(Voltage standing wave ratio) and reflection
coefficient.
 
VSWR = (1 + ñ)/(1 - ñ)
 
 
 
Will this equations applicable for differential signals?, if I am going to
measure Signal P with respect to Signal N in the differential pair.
 
 
 
If you would have any alternate solution to measure return loss of
differential signal, please suggest me.
 
 
 
Thanks & Regards,
 
 
 
Arun Kumar  P N
 
 
 
 
 
 
 
 
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