I had forgotten about one quite promising candidate -- the THAT300
matched monolithic quad. I have some of those, too. I'll put it on
the to-do list. To the best of my knowledge, they do not have
reverse protection diodes across the B-E junctions (I've never had
any reason to check).
Best regards,
Charles
I wrote:
Once upon a time, Motorola made monolithic quad BJTs -- but I'm
not aware of any matched quads similar to 2N2222s at this time.
Gerhard replied:
There still are
MAT04
HFA3046-3096-3127-3128
if duals are enough:
SSM2220
MAT12
also mat02, mat03, maybe SSM2110 [probably meant SSM2210? also,
there is SSM2212]
I had thought of these, but unfortunately, all of the AD parts (MAT
and SSM) -- which otherwise look promising -- have reverse diodes
across the B-E junctions, which rules them out as diode substitutes.
The HFA parts are small-geometry, ultra-high frequency devices (Ft =
8GHz for the NPNs), not at all like 2N2222s. It is doubtful they
would have the low flicker noise of 2222s. They are monolithic, so
they should be pretty well matched, but only the differential pair
in the 3046 is actually specified for matching -- and you couldn't
use both of the diff pair in a ring structure because of the common
cathodes. The 3127 would be the part to try. I have some, so maybe
I'll try them (but I'm not hopeful).
Best regards,
Charles
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