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Old May 6th 04, 12:41 AM
Tom Bruhns
 
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Paul Burridge wrote in message . ..
....
It'd be fun to see just how fast you can force current in and out of
an ordinary, GP power MOS FET gate to get it switching as fast as
possible, I reckon, before pressing ahead with the dedicated devices.


Back when hexfets first came out (1981 or so), I was having trouble
with them self-destructing. Back then, at least, if you read far
enough in the fine print, you'd find a maximum drain dv/dt rating. I
was seeing close to 100V in about 5nsec just before the
self-destruction as I recall. And the Siliconix V-mos transistors
were good for RF power back in that era.

If you're thinking driving it "digitally", that's probably the wrong
answer. Resonate the input and output capacitances, and life will be
much easier. Charging and discharging capacitance through a resistive
source is quite inefficient. Remember, too, that tuned triode valve
amplifiers are generally neutralized. Be VERY careful to not exceed
the gate-source voltage rating! Have fun playing, but expect some
"surprises."

Cheers,
Tom