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Best method for low frequency de-embedding

Question asked by mikejvir- on May 22, 2014
Latest reply on May 22, 2014 by mikejvir-
Hello All,

I am looking for opinions for creating an evaluation board.  My goal is the following.  I have a device, in a QFN package that is mounted to a evaluation board. This device has 200 ohm differential input and output ports.  The frequency range is 10 MHz to 500 MHz.  I only have access to an ENA (E5071B in fact).  I need to generate the S-parameters (both single ended and balanced) to the device while making the measurement at the SMA connectors of the evaluation board.  I plan to use grounded coplanar waveguide and there could be a 50 to 100 transition in the path.  Here are few ideas I have:

TRL
    Not practical since the Line must be 40 inch long.

SOLT
     Because it is low frequency, just create the SHORT (grounded via or 0 ohm SMD to ground), OPEN, LOAD (50 ohms SMD to ground) and a line.

Adapter Characterization
    Unless there is something I am missing I would need a probe for one connection which is impractical.

Modeling
     Use ADS to de-embed the device. Two ideas:

Idea 1.   Create a through line.  I would have to find it, but ADS did have a way to generate 2 S-parameters files from 1 file.  The restrictions are:

     M is used for the S-parameter measured data.
     L is for the left S-parameter data.
     R is for the right S-parameter data.

     S22L = S11R
     S21L = S21R
     S12L = S12R

This is a recursive set of equations.

Idea 2.  Find or create a S-parameter file for the SMA connector.  Create a circuit that models the connector, 50 ohms transmission line, transition, and 100 ohm transmission line.  Use this with the de-embedding element (NEG2).


I did browse the forum but everyone seems to be talking high frequency.  I am looking for opinions on the pros and cons of the above approaches.  If I missed a solution, please let me know. If I missed a previous post on this subject, I apologized.

Thanks in advance for you help.

Sincerely,

Mike Virostko
Integrated Device Technology  

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