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'[OT]: Multiple emitters and collectors'
2001\10\20@165458 by Jinx

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Just wondering -

Was drawing up a couple of circuits and had an IC internal schematic on
the desk for comparison. Many of the trannies in the IC schematic appear
to have multiple emitters or collectors, others don't and are drawn
conventionally. Seen them for years but never thought to ask before. Do/
can embedded trannies have multiple E/Cs ? Reasons ?

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2001\10\20@174042 by Gerhard Fiedler

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At 09:52 10/21/2001 +1300, Jinx wrote:
>Was drawing up a couple of circuits and had an IC internal schematic on
>the desk for comparison. Many of the trannies in the IC schematic appear
>to have multiple emitters or collectors, others don't and are drawn
>conventionally. Seen them for years but never thought to ask before. Do/
>can embedded trannies have multiple E/Cs ? Reasons ?

Yes, they can. The reason is that a transistor is a three-dimensional
structure in a semiconductor block, with different donations creating
emitter, base and collector, one usually inside the other. So it's well
possible to create structures with multiple donation areas.

The reason that they get used more inside ICs than as discrete parts is
probably that the usefulness of these multi-whatever parts is usually
limited to a very specific circuit.

ge

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2001\10\20@190945 by Bob Barr

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Gerhard Fiedler wrote:
>
>At 09:52 10/21/2001 +1300, Jinx wrote:
>>Was drawing up a couple of circuits and had an IC internal schematic on
>>the desk for comparison. Many of the trannies in the IC schematic appear
>>to have multiple emitters or collectors, others don't and are drawn
>>conventionally. Seen them for years but never thought to ask before. Do/
>>can embedded trannies have multiple E/Cs ? Reasons ?
>
>Yes, they can. The reason is that a transistor is a three-dimensional
>structure in a semiconductor block, with different donations creating
>emitter, base and collector, one usually inside the other. So it's well
>possible to create structures with multiple donation areas.
>
>The reason that they get used more inside ICs than as discrete parts is
>probably that the usefulness of these multi-whatever parts is usually
>limited to a very specific circuit.
>

Could another possibility be that you get an increase in current handling
capability by having multiple bond wires from the die to the package pins?
(This may a way-off-base possibility. I don't know what range of wire sizes
is possible for the wire bonding process.)

Does anyone know if discrete transistors are die-bonded with heavier wire
than IC's? It almost seems that they'd have to be.

Regards, Bob


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2001\10\21@054659 by uter van ooijen & floortje hanneman

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> Was drawing up a couple of circuits and had an IC internal schematic on
> the desk for comparison. Many of the trannies in the IC schematic appear
> to have multiple emitters or collectors, others don't and are drawn
> conventionally. Seen them for years but never thought to ask before. Do/
> can embedded trannies have multiple E/Cs ? Reasons ?

AFAIK the these multi-emitter T's are use only in TLL input stages. They are
used as a multi-diode AND stage. The only reason to use a multi emitter T
instead of separate diodes is that the T uses less chip area.

Wouter van Ooijen

Van Ooijen Technische Informatica: http://www.voti.nl
Jal compiler for PIC uC's:  http://www.xs4all.nl/~wf/wouter/pic/jal

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2001\10\21@105712 by Gerhard Fiedler

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At 19:09 10/20/2001 -0400, Bob Barr wrote:
>Does anyone know if discrete transistors are die-bonded with heavier wire
>than IC's? It almost seems that they'd have to be.

With respect to bonding, there's no difference between a single transistor
chip and a more complex integrated circuit; both are usually silicon
substrates wth donation areas. There are ICs with high-current connections
that need thicker bonding wires than CMOS inputs or low-power transistors
(and that have the corresponding larger donation areas for the current).

ge

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2001\10\22@091144 by SkinTech

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> ----- Original Message -----
> From: "Bob Barr" <spam_OUTbob_barrTakeThisOuTspamHOTMAIL.COM>
> To: <.....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU>
> Sent: Sunday, October 21, 2001 1:09 AM
> Subject: Re: [OT]: Multiple emitters and collectors
>
>
> > Gerhard Fiedler wrote:
> > >
> > >At 09:52 10/21/2001 +1300, Jinx wrote:
> > >>Was drawing up a couple of circuits and had an IC internal schematic
on
> > >>the desk for comparison. Many of the trannies in the IC schematic
appear
> > >>to have multiple emitters or collectors, others don't and are drawn
> > >>conventionally. Seen them for years but never thought to ask before.
Do/
{Quote hidden}

are
> having equal currents. Assuming the emitters have the same area; if not,
you
> can scale current ratio's by area scaling. That gives you easy way to set
> ref/bias currents or to built current mirrors.
>
> Jan Didden
>
> >
> > Could another possibility be that you get an increase in current
handling
> > capability by having multiple bond wires from the die to the package
pins?
> > (This may a way-off-base possibility. I don't know what range of wire
> sizes
> > is possible for the wire bonding process.)
> >
> > Does anyone know if discrete transistors are die-bonded with heavier
wire
> > than IC's? It almost seems that they'd have to be.
> >
> > Regards, Bob
> >
> >
> > _________________________________________________________________
> > Get your FREE download of MSN Explorer at
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> >
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> > (like ads or off topics) for you. See http://www.piclist.com/#topics
> >
> >
>
>

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2001\10\22@163425 by Peter L. Peres

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> Does anyone know if discrete transistors are die-bonded with heavier
> wire than IC's? It almost seems that they'd have to be.

Some discretes are bonded with really thick wires, like TO3 cased
semiconductors. Beyond that (about 20A) stud-mounted devices are used.

Peter

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