[sdiy] Bending a Sum

[ASSI]

On Monday 18 November 2013, 14:29:48, Tom Bugs wrote:
> It is around the area of linearizing the response of an SSM2164 - but,
> at the moment (blah blah) I wanted to see if I can achieve a rough
> linearization WITHOUT using the well documented Irwin EDM technique.
> 
> http://bugbrand.co.uk/images/SumBend.jpg
> 
> I just have a simple opamp sum stage to generate 5V to 0V from a 0V to
> 10V control - that's the green line.
> The standard linearization technique achieves the blue line.
> How could I bend green to blue without too much extra complexity and,
> crucially, without using another 2164 cell?

You need a logarithmic amplifier, which are a bit difficult to compensate 
but otherwise standard fare. But other than that you would want it to be 
matched to the SSM2164 response, both in control curve and thermally.  It 
may be a better use of resources to just suck it up and spend the extra 2164 
cell.


Regards,
Achim.
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