>
>
> 1.)  What are these things called?  I've been calling them "split emitter"
> or "split collector" transistors because I've seen that in print before --
> but I'm not sure I'm using the term correctly.


That's how I've heard them described, or "multiple collector/emitter".

2.)  I assume that these are somehow doped differently than a normal BJT,
> but I don't know how.  Does anyone?  Would a "split collector" NPN
> transistor be similar to two discrete matched NPN BJTs connected together
> at
> the base and emitter, but connected separately at the collector?


Email Bob Pease at National Semi.  He knows.

  3.)  Why are these used?  I assume it has to do with maintaining current
> ratios in different sections of the op amp by using a common device to set
> those currents.


Yup. The matching is supposed to be excellent.

4.)  Finally, do these devices exist as stand-alone in monolithic
> packages, or are they always buried deep in some silicon wafer?  What I
> mean
> is, are these the kind of thing I could (or would want or need to) use on
> a
> breadboard?



You used to be able to buy them, but they were specialty items.
I haven't seen any in the wild for many years now.


4a.)  Is there some reference book or website that explains these devices
> so I don't have to bother you all?


You've already found AofE, I don't remember anything else that would be all
that helpful, other than studying older National Semi linear databooks.
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