[sdiy] Temperature Compensated Exponential Converter Using SSM2164

[Ian Fritz]

At 06:15 PM 8/29/2009, Michael Zacherl. wrote:

>On Aug 29, 2009, at 11:41 PM, Ian Fritz wrote:
>
>>At 02:51 PM 8/29/2009, Magnus Danielson wrote:
>>>Ian Fritz wrote:
>>>>At 11:37 AM 8/29/2009, David G. Dixon wrote:
>>>>>  2164 is advertised to give more than five orders of
>>>>>magnitude of log conformance, and we only need about three for a
>>>>>VCO, so I'm
>>>>>not worried.
>>>>Conformance at what level?  Do they say?
>>>
>>>The SSM2164 has log control input and claim good conformance for
>>>100 dB, which cranks out as 5 orders of magnitude. If you look at
>>>the design you will see that CV hits the control voltage input
>>>while the current input is wired to -15V.
>>
>>The question is how *accurate* is the conformance over the 5
>>decades.  1%?  5%? ...
>
>that's the point: I wouldn't mind if the scaling is 0.9 or 1.1 V/Oct.
>or whatever or how's the log conformance in general, only if the VCOs
>in use behaved exactly the same as much as possible. IOW connect them
>to the same CV and how much they do get apart over the range?

To be clearer, it is magnitude of the deviation from a log function that I 
am asking about.  It has nothing to do with .9 vs 1.1, since that is set by 
the v/o trimmer.

Ian