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

  • From: "Arun kumar P N" <arun@xxxxxxxxxxxxxxxx>
  • To: "'steve weir'" <weirsi@xxxxxxxxxx>
  • Date: Mon, 13 Apr 2009 19:43:44 +0530

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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