Since double gate MOSFET transistors are no longer being made in
silicon, supplying modified transistors is more than a little difficult.
Seems to me that the forward transconductance of 10 to 15 millimhos is
normal for the 3N200, and IDS will have some variations from transistor
to transistor. There might need to be some selection, but since they
haven't been made in several years, finding them in a quantity of 2500
after selection may be impossible. I have no source. You can do an
internet search on the part number, there are a few places with stocks
of obsolete transistors that may be able to supply. I doubt the makers
of obsolete transistors have made any because the silicon double gate
MOSFET went out of production because the production machinery was based
on 2" diameter silicon wafers and the vendors of silicon wafers scrapped
all their crystal growing equipment that small.
NTE Electronics latest cross reference shows a replacement using their
NTE-222. Last I priced it, it was fairly expensive. The specifications
for it show IDS can have a range of 5 to 35 ma, and Gm is typically 12
millimhos. It may be possible to select transistors from their stock to
meet your specifications.
Gerald J.
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Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
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