Detector/diode question
Many detectors using diodes have an active bias voltage/current applied.
An Autek WM-1 peak reading watt meter is a great circuit of said. cheers skipp http://sonic.ucdavis.edu : Clifton T. Sharp Jr. wrote: : I was going through my bookmarks when I came upon one about diodes : (http://uweb.superlink.net/bhtongue/7diodeCv/7diodeCv.html). In his : third paragraph, the author asserts: : For RF diode detectors to work, one needs a device that has a : non-linear V/I curve. In other words, the slope of the V/I curve : must change as a function of applied Voltage. The slope must be : steeper (or shallower) at higher voltages and shallower (or steeper) : at lower voltages than at the quiescent operating point. : If there's any truth to this, someone please enlighten me. I've always : been of the belief that an envelope detector diode would be most perfect : if the diode was a perfect switch, i.e. zero attoamps reverse current : and perfectly linear forward current (as though the diode was a wire : during the forward conduction period). I don't see how a changing slope : during forward conduction could do anything other than distort the : demodulated waveform, especially on tiny signals. : -- : The function of an asshole is to emit quantities of crap. Spammers do : a very good job of that. However, I do object to my inbox being a : spammer's toilet bowl. -- Walter Dnes |
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