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I've got a 900MHz downconverter design which I'm trying to convert for a 100kHz single ended RF input and LO input. I'm not sure how to calculate the required capacitor and inductor values, so any help would be greatly appreciated!

900MHz Downconverting Mixer

Ricardo
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Shane
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1 Answers1

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I think you may be pushing the data sheet to extremes for a frequency of 100kHz. The nearest circuit in the data sheet that matches your requirements is this: -

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This down converts to 450kHz and uses an op-amp on the output so immediately you don't need to worry about a bunch of inductors - just use the op-amp instead for servicing your needs. Should you require additional filtering - use more op-amp stages.

The above circuit down converts at 90MHz using a 90.45MHz local oscillator - the two remaining inductors are there to match impedances for the RF input. At 100kHz just use an op-amp to drive IN+ and don't worry about matching at all because at this frequency it just won't matter - the input op-amp I mentioned needs to be reasonably fast and feed it's output to the IN+ via something like a 220R resistor.

Andy aka
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  • @Shane feel free to accept the answer if you think it's useful but maybe wait another day (or so) to see if anyone else answers. – Andy aka Sep 11 '14 at 07:21