>From memory, the original diodes are matched to a 5mV forward drop at 1mA. You
>can get some funny results if they aren't matched, as you get some of the
>switching signal coming through - from memory. teh effects will be at maximum
>sensitivity.
As Steve says, getting diodes from the same batch will probably do it. It's
just that matched diodes come from about the same place on the wafer: it is not
uncommon to get a variation across a wafer, although it's probably more
apparent with the 12 inch wafers used these days for CMOS. This semiconductor
processing stuff is far more of a black art than the manufacturers would have
you believe - you have to have the right person spit in the mixture!
Not that 27 years working in the semiconductor business has made me cynical -
and no comments from GM3SEK on that!
73
Peter G3RZP
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