On Wednesday 03 March 2010 11:57:36 Greg Cunningham wrote:
> On Tue, 2010-03-02 at 21:21 -0800, Donald Tillman wrote:
> > On Mar 2, 2010, at 2:35 AM, Peter TB Brett wrote:
> > > The usual approach is to buy SMT packages containing 2 or 4
> > > transistors on
> > > a single piece of silicon (i.e. literally back-to-back on the wafer).
> > > They're invariably well-matched enough for all but the most ultra-
> > > precise
> > > applications, in my experience.
> >
> > Which dual/quad transistors are these? Who makes them?
Well, just about everybody who makes transistors makes them. NXP have the
BCM847, for example. Admittedly quads are much rarer than duals.
> > (And back-to-back? Are you sure? That doesn't sound right. That
> > would have to involve separate processes for each side, and so the
> > transistors wouldn't be matched.)
> >
> > Most dual transistors I've seen have the transistors on separate
> > dies. And so there's no matching and no offset spec; it's just like
> > picking up 2 or 4 individual transistors.
>
> ...me thinks Pete had a long-tail-pair schematic in his head at the
> time. Probably meant side-by-side on the die.
Correct.
Peter
--
Peter Brett <peter@xxxxxxxxxxxxx>
Remote Sensing Research Group
Surrey Space Centre
Attachment:
signature.asc
Description: This is a digitally signed message part.
_______________________________________________ geda-user mailing list geda-user@xxxxxxxxxxxxxx http://www.seul.org/cgi-bin/mailman/listinfo/geda-user