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IQ phase Error and Image rejection - RF Cafe Forums
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wallace0075
Post subject: IQ phase Error and Image rejection Posted:
Tue Sep 12, 2006 12:06 pm
Lieutenant
Joined: Fri Feb
11, 2005 6:32 am
Posts: 4
hello guys,
two questions:
I have a device (Zero-IF) and an analyzer with IQ inputs , I'd like
to measure- the image rejection. How can I do it?
-what is the
relation between IQerror and image rejection??
regards,
Wallace
Top
jaslovkel
Post subject: Posted: Tue Jul 10,
2007 10:53 am
Captain
Joined: Tue Jun 26, 2007 10:27
am
Posts: 11
Location: Dallas, TX
Hi wallace0075,
For Image Rejection you may need to do a basic theoretical analysis.
You can set up a basic block diagram (signal flow diagram) for an I/Q
receiver. Add some gain mismatch in one path and add some phase mismatch
to the LO path. Then, sum up the outputs of the I and Q paths (you can
take the difference also, and get the same relationship) so that you
end up with a SSB response at the output.
Your expression will
then contain an expression for the desired frequency and for the sideband
frequency. You then take the powers of the desired and undesired and
take the quotient. This will then give you an expression for SBRR based
on amplitude and phase mismatch.
An example of this can be found
here:
http://ieeexplore.ieee.org.ezproxy.tamu ... mber=33037
Hope this helps!
-J
Posted 11/12/2012
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