Tempco Resistors

[Joachim Verghese]

On Fri, 3 May 1996 gstopp at fibermux.com wrote:

>   Also, it the optimum tempco +3300ppm/C'? I've seen +3000 used before...

Good question. I've seen anything between +3000 and +3600 in
commercial designs. I seem to recall that +3300 is theoretically
the best near room temperature (from calculations based on Vt = kT/q),
but I fear that in practice, this is individual per transistor. Maybe
if we select only those transistors with -3300ppm/C:..... :))

Anyway, I've used the 1k Farnell type a lot, but only for VCFs.
(The VCOs are compensated with software). I seldom use VCFs for
oscillators, so I can't really comment on the performance or
suitability of the Farnell type (+3000ppm/C).

-joachim