[sdiy] SSM2164 and *one unit* tempco idea!

[HOSHUYAMA]

Hello KD,

I considered similar idea a couple of years ago, but abandoned. 
(I'was and am thinking of 2164-based synth like Roman Sowa ;-)  
Your approach looks different from mine.  I'd like to know the 
details of your idea.

I tried to design a VCO (without tempco) using one unit in 2164 for 
exponential converter and another for tempco.  The disign was very 
difficult for me because its temperature dependency is not linear.  
After compromise, I managed to draw a schematic.  However, I couldn't 
think it is a better design than ordinary tempco-based method, 
because it is complicated and requires adjustment.

Sam HOSHUYAMA
Saitama, JAPAN


Date: 2007/04/04 06:10:39
karl dalen <dalenkarl at yahoo.se> wrote:
> Idea!
> 
> In order to compensate for the temp drift in the SSM2164 one usually takes
> a tempco, or ntc for each expo,but since here all the expos are on the same
> die and therefore (not matched) but at least on the same die close they
> would be quite equal in terms of temp drift one could take one tempco/ntc
> thermally place it in contact with the top SSM2164 or below (missionary sex
> formation) then take the sensed value, scale it to match each expo input and
> then simply add this drift coefficient to each expo input.
> 
> The idea are instead of having four tempcos (which would be expensive)
> you can use one dirt cheap NTC for instance, if the NTC bails the entire 
> chip will bail instead of having to figure out which OTA of four or more bails
> out in the case of using four NTC's.Also you save components, and PCB
> real estate and its cheaper!
> 
> Ideas about this idea!
> 
> Reg
> KD
> 
> 
> 	
> 	
> 		
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