Differential measurement with baluns - RF Cafe Forums

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mbergmann
 Post subject: Differential measurement with baluns
Posted: Tue Jun 17, 2008 5:55 pm 
 
Captain

Joined: Mon Jun 19, 2006 10:27 am

Posts: 13

Hello,

I have to make measurements on differential devices with a network analyzer, for which I purchased two Baluns from Minicircuits (ZFSCJ-2-1, SMA).

How do I have to carry out the calibration on the VNA ?

open is open

short is simply a connection between the two inner conductors of the two outputs of each balun ?

match would be a 50 Ohm resistor mounted on each output or do I have do connect the two inner conductors with each other with a 100 Ohm resistor between them ?

Frequency range is 1 MHz - 500 MHz.

P.S.: Please don`t tell me that measurements with baluns are a piece of !"ยง$%&(/%$?, I talked about this topic with my boss, but we just have got an old VNA and we don`t have got the money for a new one with differential capabilities.

P.P.S.: I also know that there doesn`t exist anything like a `real` calibration standard for differential measurements, but I talked about this with my boss and ... you know the rest of the story, don`t you ?
 
   
 
FSomma
 Post subject: Re: Differential measurement with baluns
Posted: Wed Jun 18, 2008 5:05 pm 
Actually...

open is open

short is short

and load is the characteristic impedance of your VNA
 
  
 
gui076
 Post subject:
Posted: Fri Jul 25, 2008 7:02 am 
 
Captain

Joined: Mon May 05, 2008 9:56 am

Posts: 17

Location: France

Hi all,

My question is pratically the same.

I would like to measure a differential Low-Pass filter with a VNA.

I have seen some subjects with S parameters transformations or something like that but i have not found procedures on how use the VNA for this measures.

Does anyone have an idea ?

guillaume
 
   
 
nccu1990
 Post subject:
Posted: Sun Aug 10, 2008 10:05 am 
 
Lieutenant

Joined: Sun Jul 27, 2008 10:29 am

Posts: 1

You can read the R&S application note

1EZ53: Measuring Balanced Components with Vector Network Analyzer ZVB

https://www2.rohde-schwarz.com/en/produc ... |-904.html

More important one is you must define the correct differential impedance in the port configuration of VNA.

gui076 wrote:
Hi all,

My question is pratically the same.

I would like to measure a differential Low-Pass filter with a VNA.

I have seen some subjects with S parameters transformations or something like that but i have not found procedures on how use the VNA for this measures.

Does anyone have an idea ?

guillaume
 
   
 
mac
 Post subject:
Posted: Tue Dec 16, 2008 4:24 am 
 
Captain
User avatar

Joined: Fri Nov 02, 2007 3:45 am

Posts: 10

Location: germany

Hi,

just a simple coment -

don't know if it helps but

think about it

can't you use two baluns of the same kind,

measure them back to back and calibrate them into your

network analyzer setup -

now connect your filter or whatever in between and measure your response etc.

mac

_________________

regards

mac

Posted  11/12/2012