[sdiy] Nice info on decoupling caps

[David G Dixon]

> A nice little intro on decoupling caps for the uninitiated. 
> Some good links for more info at the bottom of the article too:
> 
> http://www.analog.com/en/all-operational-amplifiers-op-amps/op
> erational-amplifiers-op-amps/products/RAQ_JBryant_In_and_Out_I
> ssue76/resources/faq.html?display=popup

I found this article to be frustratingly terse.  "Many ICs have internal
circuitry which generates HF noise on the power rails" doesn't really tell
me anything!  Am I to believe that an opamp generates HF, just because?
Why?  If so, then wouldn't every transistor also require decoupling?  Where
does it end?

I tend to use only one pair of decoupling ceramics on each module; two pairs
if it is a big module, or if it has digital stuff on it (which is fairly
rare).  I've never had any problem which could be solved with more
decoupling.  Maybe I've just been lucky, but I think that, for most analog
synth circuits, this advice of putting caps on every IC is simply needless
overkill.