Temperature compensation (Was Re: [sdiy] Exponential converter information)

[Ian Fritz]

At 08:14 PM 6/20/05, James Patchell wrote:
>The major temperature drift term in an expo converter is the scale factor 
>(i.e. the number of Volts/Octave)...changing the reference current to the 
>expo pair will only affect the offset drift.  To compensate for the scale 
>factor drift you must use either a Tempco Resistor in the feedback loop of 
>an op-amp...or use a multiplier

Or you can use a tempco in a voltage divider before the converter transistor.