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Question Re: AD8343 S-Parameter Data

Question asked by Angie on Aug 16, 2011
Latest reply on Sep 19, 2011 by Qui

Hi all,

 

I've been trying for some time to figure out how to use the AD8343 (first time trying anything RF, actually), and I just wanted to verify a few things. I've been using the S-Parameter file supplied by AD to do impedance matching (using LVDS data output from an FPGA as the LO input and ~300 MHz signal from a function generator as the IF input), and when I simulate in Cadence, after impedance matching the IF and RF ports to 50 Ohms (so that at least S11 and S22 are minimized at my frequencies of interest), I get that the magnitude of S21 is on the order of 0.13 (before impedance matching, it was <<0.1). As far as I understand, S21 = VRFOut/VIFIn, so I'm a little confused as to what I'm doing wrong, if the mixer is speced for a typical conversion gain of 7dB. Is there any way to know what kind of conversion gain to expect at an output frequency of around 300-350MHz if the conversion gain # can't be used? If I'm not mistaken, the LO power also affects the gain, so is it appropriate to expect that the LO power used to test was the "typical" -10dBm?

 

Is the S-parameter data file actually sufficient to be able to create a matching network, or would it be very much advised to get impedance measurements for myself? Also, I'm having trouble understanding how I should go about verifying that the mixer is common-mode stable at the output, since I'm doing a differential to single ended conversion there.

 

Are there better recommendations for mixers operating at that frequency requiring differential inputs/outputs with 50Ohm impedances?

 

Thanks for the help,

 

Angie

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