Quote:
Originally Posted by Argus25
Firstly there is the problem (for a detector with a positive output polarity) of negative peak clipping that always occurs when the modulation reaches some frequency threshold. It occurs because of the RC time constant that the filter the detector feeds, has an exponential discharge profile. The frequency at the point this distortion starts to appear is approximately 0.375/RC when the modulation is around 50%. It's a lower frequency when the modulation is higher. Basically the detector diode gets reverse biased due to the charge stored on the filter capacitor on the negative modulation peaks and it's not able to track the modulation envelope.
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Thanks for that gem Argus25. I have often wondered why changing the time constant of the components in the (effective) diode load can have an effect on distortion figures.