Sorry I missed your question, but I don't have a good answer. Maybe coupling through the substrate?
P channel mosfets have the S/D doped with boron, on a n type substrate. For good physical reasons (P+ concentration is usually one order of magnitude lower compared to the N+ concentration) the metallization contact on p+ is worse than on n+ so the source contact will have a larger contact resistance than the substrate contact resistasnce. This leads to the situation in which the body diode (drain-substrate, through the shorted source) will have a lower drop voltage for a given current. and will also be rather fast. A drawing of the mosfet cross section is worth more than any short written explanation.
N channel is exactly the other way around.
Note that the body diode properties have nothing to do with the channel carrier mobility in P and N mosfets. The body diode matters in switching applications with reactive loads, don't know why this would matter in linear applications.
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I'm afraid you would need to use the Larry Page amazing product and then try to understand at least the very basics of the mosfet body diode. Till then, nice try again, talking through the hat will never get you more than that.
Good luck.
Hi David,
Yes, as Scott says, TV sound is FM, and TV stereo sound uses dBx. I need a frequency generator for the FM broadcast band that modulates in Stereo. It would be nice if it was xtal controlled as my current solution is a Radiometer Copenhagen SMG1. Adjustable frequency that drifts badly. I've even attempted to take the MPX output and use that to modulate my HP 8656B generator, but I have to use a modulation analyzer (HP 8901A) to set the pilot level and modulation levels. It's an extreme pain in the rear, let me tell you! It also takes far too long, but then at least my frequency is rock solid, and I can set it anywhere in the FM band. The Radiometer is only good around 100 MHz, a busy part on the dial.
-Chris
Yes, as Scott says, TV sound is FM, and TV stereo sound uses dBx. I need a frequency generator for the FM broadcast band that modulates in Stereo. It would be nice if it was xtal controlled as my current solution is a Radiometer Copenhagen SMG1. Adjustable frequency that drifts badly. I've even attempted to take the MPX output and use that to modulate my HP 8656B generator, but I have to use a modulation analyzer (HP 8901A) to set the pilot level and modulation levels. It's an extreme pain in the rear, let me tell you! It also takes far too long, but then at least my frequency is rock solid, and I can set it anywhere in the FM band. The Radiometer is only good around 100 MHz, a busy part on the dial.
-Chris
Yes but FM broadcast is within the channel space of TV. Perhaps a small mod to a Shibasoku would work. There's so much of that stuff around and no longer any use for it. So it's cheap.
Shaw went 100% digital last week in my system. There is no more analog just QAM.
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Chris we carried FM station over the cable. This was discontinued about 3 years ago and I believe the equipment is now disposable. I'll bet it still sitting in the rack at our remote hub.
These units are essentially low power stereo FM transmitters.
Would something like this be useful to you? I can ask my supervisor if the stuff is being disposed off.