AW: Re[2]: gate voltage and logic stds

Haible_Juergen#Tel2743 HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de
Wed Feb 7 21:35:00 CET 1996


>     Remember Juergen that we're talking about ADSR generators, which
>     typically operate exclusively between ground and the positive supply
>     :-)

Sorry for this; I was in a hurry and did risk to say something not
appropriate to the topic ... the Korg stuff I mentioned was the SQ-10 ...
truely far from being an ADSR (;->)

>     You're right about BBDs - my home-built 4096-stage analog delays run
>     between -15 and ground, as shown in EN. If you happen to know any more 

>     details on why -15 is preferred, please share your thoughts because I
>     sure as heck can't figure out why it would make a difference since the 

>     electrons are flowing in the same direction! Maybe fewer (smaller)
>     noise spikes on the ground side???

I *think* that it's NMOS technology that kind of naturally uses the positive
rail as a refference point (similar as these ol' ECL circuits). The BBD's
also need one or more reference voltages between the supplies; they
also are bypassed by capacitors to a certain rail and not the other.
On the contrary, the CMOS chips that are often used to clock the BBDs don't
really care for a certain reference rail, 'cause they are built quite 
symmetrically.

JH.



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