View Single Post
  #6   Report Post  
Old May 25th 04, 03:46 PM
Michael Black
 
Posts: n/a
Default

"John" ) writes:
Does anyone know of a multimode detector IC that will handle SSB, AM and FM?
Looking at an old ARRL handbook I can see LM373. Is there a more modern
chip?

Thanks



The LM373 was a whole IF strip, a variable gain stage and then a fixed gain
stage feeding the detector. The detector itself is relatively simple.

A "Gilbert Cell" mixer can be a multi-mode detector. Obviously, it's
a product detector for SSB and CW. But put the incoming signal through
a limiter and use that as the "BFO" input and you've got an AM detector
(while the 373 has a separate AM detector, the application notes even
suggest this scheme). Limit the incoming signal, and then feed it
through a suitable phase shifter into the "BFO" input, and you've got an
FM detector.

"Gilbert Cell" mixers show up in plenty of places. The MC1330 AM detector,
and all kinds of FM detector ICs (where they are used as quadrature
detectors, as I describe above)

But I suspect at this late a date, an IC designed to be a multi-mode
detector or IF is realtively rare. There is not much demand for it.
So you have to create the function yourself.

Michael VE2BVW