gEDA-user: analog switch idea

[gene glick <carzrgr8@xxxxxxxxxxxxx>]

I'm looking for some ideas on how to multiplex some single-ended audio 
signals.  The plan is to connect the mux to a differential amp, which in 
turn drives an ADC.

The obvious (at least I think it's obvious) choice is to use some 
variety of analog switch IC. ON-semi has some decent ones actually, but 
they have a THD numbers around 0.01%.  Not bad, but not good enough 
either.  I'd like to get at least an order of magnitude better.

I recently saw a "design idea" in EDN where the author used an analog 
switch to change the gain of an op-amp to zero.  Cute idea actually. 
But, he used a really expensive low-noise op-amp.  So I guess my next 
criteria is low cost.  How low? not sure.

If it the cost gets high enough, I will design in a separate ADC such 
that each analog input has a direct and single path to an ADC.  I'll 
handle the rest in digital-land.

Any ideas?

thanks

gene



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