Importance of matching in expo convertors?!

[mbartkow at ET.PUT.Poznan.PL]

This is one question I was always affraid to ask expecting every temcpo guru
would laugh at me. But I just could not stand it anymore :-)

Why is everybody trying to compensate the temperature dependency of
a bipolar junction using unreachable tempco resistors while it might
be done just using another bipolar junction ?
I guess that an exactly opposite tempco is needed, which is perfectly
achievable using an appropriate placement of a transistor within an
inverting OA configuration (e.g. one supplying the reference current/
voltage). Why the hell isn't it done this way ?

BTW, I think a tutorial on temperature compensation would be greatly
appreciated as it still causes many confusions.

regards,

MB


--

Maciej Bartkowiak, PhD
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