[sdiy] unbuffered CMOS

[anthony]

> I assume that you are referring to using an unbuffered CMOS inverter as a
> "linear amplifier" by using input and feedback resistors to control the

Yes exactly.

> amplifier's gain.  Doing this actually consumes more current than 
> operating
> the gate as a logic gate.  And if you're trying to simulate an opamp, the 
> same
> application will usually consume less power if an opamp is used.  A gate 
> used

I remember reading at least in some applications they're biased like a Class 
A amp.

> in this manner will have a  current draw at maximum when both output
> transistors are presenting the same resistance, i.e., when the output is
> (Vdd-Vss)/2.  The actual current depends on supply voltage and a set of 
> V-I
> curves are found in the datasheets.  Gates are used like this in things 
> like
> the WASP filter.  Their nonlinearities are tube-like.  There are guitar

Tube-like. That's good to know. But is the reason for using an unbuffered 
inverter because of the increased current usage or that it sounds better? 
I've seen similar applications that don't specify unbuffered.

(I put unbuffered CMOS as the subject, and inverters were the only thing I'd 
seen used in this manner, but I wasn't sure if it would be doable with other 
types of gates and uses or not...)

> distortion boxes using the technique.  The René Schmitz 4069UB VCO employs 
> it.
> I have an ADSR that uses it.

I just started building that VCO last night. Pretty cool.

That's the main one that got me thinking about this.

Also Osamu Hoshoyama's excellent web page.

>
>>
>>And what's up with 4007UB? It wouldn't B what it B if it wasn't UB...
>
> Well, it probably just conforms to a sort of standard, the unbuffered ICs 
> had
> UB appended.

That's what I thought.
>
>>I wish there was a bipolar version of sorts. I have lots of NPN arrays, 
>>but
>>PNP's I don't find much. Both in one package might be very useful.
>
> That's why I like the 4007...

Yeah I like it just about as much as the 4046.