[sdiy] Temp comp of OTA and the expo!

[Karl Dalen]

NS once reported that the tempco of the Gm in their LM13700 is 
-3300ppm C. Since this would then be the very same amount of
temp drift as in a ordinary exponential converter (-3300ppm/C)
how would i temp compensate for the "total" temp shifts" properly"
if a standard PNP exponential converter used as current controll? 
What if the drift in the expo are e.g -3100ppm and the Gm cell 
are -3350ppm, how do one actually temp compensate this situation??

And what if they are phusically spaced a bit from each other,
then the temp drift rate would not be equal, e.g i suspect they 
start to drift at different time positiuons!!! Urgh!!!

I mean, it would be nice to have a drift free multimode filter
in resonating mode!
Any sugestions?? Heating the Gm cell by using the darlington pair
as heater would perhaps remove the 3300ppm of the Gm cell!!!

Thanks!
  
Regards
KD

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