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Differential RF input for ADL5380 eveluation board

Question asked by biancajs on Sep 10, 2014
Latest reply on Sep 11, 2014 by bsam

Hi there,


I have the ADL5380 evaluation board (I think the newer version which is smaller and doesn't have the enable pin SMA input. We have the older one also). I would like to use the differential output from a fast photodiode as the RF source. We are currently using just one output with the demodulator in it's single-ended config, but would like to benefit from the doubling in signal we would get from using both outputs.


There are obviously differential inputs (RFP and RFN) for the RF, though no instructions on how to reconfigure the board in the data sheet (there are instructions on how to reconfigure the I and Q outputs).


I assume that I am able to do this by removing R11 and populating R24 with 0 Ohms, then removing the two capacitors C5 and C12 then populating C4 and C14 with... 0 ohm resistors? Or should the capacitors from C5 and C12 be placed here?


There is also a blue spot on the board over the tracks for the RFN input - I haven't seen this before, is this just to mark the board in some way or does it have a purpose?


I have attached a photo of my board if this helps.


Thanks for your help,