AW: LOG100 current mirror

[Rene Schmitz]

At 13:47 30.08.99 +0200, you wrote:
>Not many replies to this topic so far ...
>Interesting circuit - selected diodes should work as well as the expensive
>LM394 (?) - the transfer courve of the transistors / diodes performs a
>compression
>of the operating voltage for the opamp mirror - this should help avoiding
>offset
>problems from them opamp, and keep the voltage drop low.

The LM394 has reverse protection diodes, so that one wouldn't need the
extra diodes.
This may be the reason why they chose it, but as you say it should work
with matched diodes.

>Next shot, use a p-channel JFET. Should work, but not a cheap
>solution either.

What about darlington connected PNPs as common base amplifier? 
The 1/beta error should become insignificantly small. 
Same order of error term as for a three transistor current mirror...

Bye 
 René
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