Mon May 26 21:04:56 EDT 2014
temperature and v_be mismatch - final words?
Assumptions (seem to be correct):
* I -> V_be -> r x V_be -> I
is temperature stable as long as transistor are thermally coupled.
* Offsets are static and can be calibrated at production time as long
as a significant margin is used.
-> This is different from "real" analog gear where either good
matching is required, or trimpots are used to compensate offsets.
Why is this "averaging" circuit not used in more classical analog
designs? Dependence on opamp offset maybe? No, that can be
compensated for. Yes, what's wrong with it?