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How to design a square-law diode detector?

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raed_microwave

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Hi dears,

I'd like to design a diode detector with square-law characteristics and I need to how to design it? As I know from its basic circuit that it consists of impedance transformer, RF choke, diode and bypass capacitor. I need to know how to calculate the input impedance of diode to design the impedance transformer and how to calculate the bypass capacitor?[/img]
 

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Re: Square-Law Detector

biff44 said:
try these papers on diode detectors:

Hi biff44,

I have checked these papers but I couldn't find any formula that can be calculated the bypass capacitor or the components of impedance transformers.
please I need to know how to calculate it or to find an example of design.

Thanks in advance
 

biff44

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Re: Square-Law Detector

Here are a few papers on RF input impedance.

As for bypass cap, you want it big enough (and low inductance) so RF energy does not go flying out the DC port. On the other hand, you do not want it so big that the video bandwidth of the detector is small. Remember, there is a big R-C time constant, since the diode R is big. I would guess you want 100 pF or so.
 
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