double quadrature detection - RF Cafe Forums

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jmariano
 Post subject: double quadrature detection
Posted: Thu Feb 03, 2011 10:51 am 
 
Lieutenant

Joined: Tue Nov 30, 2010 11:36 am

Posts: 1

Dear All,

Does any one know her I can find a description/analysis of the so called double quadrature detector? This is basically two IQ detectors acting on the RF signal and on a 180 shifted version of RF. Then, you make 0-180 and 90-270, to get I and Q.

This is supposed to have better performance than the simple IQ detector, but I don't know why.

Tanks

josé mariano
 
   
 
troy
 Post subject: Re: double quadrature detection
Posted: Thu Apr 28, 2011 4:30 pm 
 
Lieutenant
 

Joined: Mon Feb 25, 2008 4:53 pm

Posts: 4

If I understand what you're talking about, a double quadrature converter is where basically where two sets of I/Q mixing paths are used. The I signal is mixed with the 0deg and 90deg LO signal to create basically an Ii and an Iq signal, and the Q path is mixed with the same 0deg and 90deg LO to create a Qi and a Qq signal. Then the Iq and the Qi are mixed to generate the Q output, and the Ii and Qq are mixed to generate the I output. What results is a cancelling of the image frequency in a way that is more broadband that when done only with diodes and transformers. I tried to find a good picture of it for you online but couldn't find anything.

Posted  11/12/2012