Question Re: AD8343 S-Parameter Data

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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