[sdiy] Temperature Compensated Exponential Converter Using SSM2164

[Michael Zacherl.]

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?

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