Active rectifier AM demod

Thread Starter

AnalogKid

Joined Aug 1, 2013
9,186
Stringing up outdoor lights, had a thought ...

In the world of analog signal processing, the active ("ideal") rectifier opamp circuits (half-wave and full-wave) have been around since the 60's. Back then, the idea of running 1.6 MHz through one was somewhere between a pipe dream and a joke.

Fast-forward 50 years, and there are some pretty fast opamps available. Has anyone tried, or seen, a broadcast band AM demodulator with an opamp active rectifier as the detector?

ak
 

Audioguru again

Joined Oct 21, 2019
2,998
Does anybody listen to the awful muffled sounds from an AM radio anymore? The radios picked up lots of amplitude clicks and pops.
The old diode detector works fine and does not need to be replaced with an active rectifier.
 

MrChips

Joined Oct 2, 2009
23,250
One of these days I hope to get back to my digital radio project. I can digitize the signal at 50Msps and do the demodulation in software.
 

Audioguru again

Joined Oct 21, 2019
2,998
In the dark ages there was only 1 or 2 AM radio stations in town so selectivity was not needed.
Today there are many AM radio stations near and far so the needed selectivity of an RF stage followed by a few stages of IF filters and amplifiers produce a whopping high output for an ordinary diode to be the detector.
 
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