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AD603 outpout impedance match

Question asked by huletlab on Sep 25, 2017
Latest reply on Sep 25, 2017 by jstaley

Hi all,

 

I am using the evaluation board of AD603 to control the output power of a VCO. The problem is  the input and output impedance of this VGA is not 50 ohm. But all of my other components have a 50ohm impedance. 

 

For the input port, I put a 100ohm resister in parallel, and it works fine. Then I added a rf attenuator at the output port to match the impedance. But it seems like there are still some portion of the signal got reflected by the attenuator, so the power output is 10-20dB's lower than what it should be. I just want to ask what should I do to eliminate the reflection? Should I use a balun instead, or can I replace the 453ohm resistor at the output port with a 50ohm one? Thank you so much for your help.

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