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Vector Mixer Calibration with PLL in LO path

Question asked by cserrano on May 8, 2017
Latest reply on May 9, 2017 by daras

On a PNA-X, I want to perform a vector mixer calibration where the LO for my DUT’s mixer is being set by a PLL (internal to the DUT).  The signal generator for the “LO” is really setting the PLL reference frequency, so it is not equal to f[Port 1] – f[Port 2].  What is the best way to set up this type of vector mixer calibration?

 

As a simple example shown below, say I have an 8 GHz reference signal with a PLL generating a 9 GHz LO, with the DUT input = 10 GHz and DUT output = 1 GHz.  If I set up the VMC with an LO of 9 GHz, it won't work since the source needs to be 8 GHz for the DUT.

 

Do I need to add an identical PLL to the Reference Mixer path, and tell the PNA that the LO is 9 GHz instead of the 8 GHz reference frequency?  Or would a calibration work with two sources generating 8 GHz & 9 GHz if their 10 MHz ref are tied together?  Any other way to do this?

 

VMC with PLL diagram

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