[sdiy] PCB op-amp layout - 2x2 or 1x4

[Quincas Moreira]

Thanks David.  I noticed the crosstalk issue in a Module I was testing for
production. Voltages in the buffer for the multiplexer was affecting the
one for the CV input.  Our designer has since changed it to avoid the
problem.

On Sat, Nov 7, 2015 at 11:46 PM, David G Dixon <dixon at mail.ubc.ca> wrote:

> >> I don't get the issue with the power being on the "wrong side" as these
> chips are symmetrical, one could just turn it around and have the power
> pins
> facing the "right direction."  What I do worry about is interaction between
> opamps in the same package.  Depending on what you're doing it may indeed
> be
> better to use a few duals rather than quads.  In the real world, isolation
> between Opamps in the same package can be less ideal than the specs say.
>
> The quad power pin thing is an annoyance, but a bloody needless one.  Why
> did they do it that way?  It just means all the quads need to be installed
> upside-down.
>
> The isolation thing is true.  "Crosstalk attenuation" for TL07X is rated at
> 120dB.  It ain't!  At least not at 2000 Hz.  120dB should be dead silence.
> However, high-pitched squeals will happily slip from one opamp to another
> in
> a TL074.
>
>


-- 
Quincas Moreira
Test Pilot at VBrazil Modular
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