Sat May 31 01:58:12 EDT 2014

Reverse saturation

I'd like to derive this again[1]: an explanation for the use of a
transistor in reverse saturation to make a current controlled
resistor.  I'm not sure I really get why it has to be reverse and not
forward.  Is this just to make the resistance value say 50x larger?

To understand, look at the point where reverse and forward beta are
compared: that's where the approximations will differ.  Though
following that through gives a similar expression.

Check again...

[1] http://www.timstinchcombe.co.uk/synth/MS20_study.pdf