[sdiy] Having a hard time finding the chips you want - roll your own!

[Scott Bernardi]

Gad, I would love to do my own custom chips.  Just a standard bipolar process
(that gives you the best analog performance, anyway); but even that has 7-8
layers. Even if you had a nifty program to do your component layout with,
there's still the cost to shrink and step-and-repeat to produce the masks, then
go through wafer fad, then saw the die apart, test and package.
Here's some simple stuff I'd start out with:


"Kit parts". These are standard geometry transistors in various sizes and
configurations that you could wire up to breadboard your design. Just use
regular 1% resistors and silver mica caps (integrated circuit resistors have a
20% tolerance, but match with 0.1 - 0.2%. Caps bigger than about 100pf are
impractical on ICs due to size).
Matched transistors; dual MAT nun's, and decent pap arrays up to quints (the
quads always have one missing when you want to do a current mirror with four
outputs to drive stages for a four pole filter!).
High quality temperature compensated exponential current sink/source.
Oat's
SSM2040 type filter, with gm stages independent so you can hook them into
whatever configuration you want.
VICARS


Rob B wrote:

> Oh my god!! Geek hell!!!
>
> HAHA!!
>
> It *does* look very interesting though.. I mean, most books I have read
> lately all say that in the future, the only way to make money will be to own
> a small home factory with doing ultimately customizable one offs for each
> customer. Where the economy started with 1-2 man operations, then progressed
> to million man operations, so shall it again fall back to 1-2 man operations
> when technology catches up. This is a harbinger of the *real* new economy,
> not that virtual crap all the silly ppl threw money at (okay, ill admit, i
> was tempted)
>
> No storage, no warehousing, very little wait, no overhead to speak of, just
> great products in exactly the functionality, colors and schemes the customer
> wants.
>
> Maybe I smoked some bad stuff in my heydey too, but, who knows for sure..
> hehe.
>
> So, in this new barter system/small scale economy, who wants to be the town
> chipsmithy? hehe. Im already the plastics parts/machining smithy.
>
> aim : cybrgzr0 <--last thing is a number
> ----- Original Message -----
> From: Magnus Danielson <cfmd at swipnet.se>
> To: <synth-diy at dropmix.xs4all.nl>
> Sent: Tuesday, August 28, 2001 4:58 PM
> Subject: [sdiy] Having a hard time finding the chips you want - roll your
> own!
>
> > Dear all,
> >
> > I constantly hear people looking for this and that chip, but have a
> > hard time finding it. Since we are all more or less into the mad
> > scientist level, it is just logical that we eventually will go for the
> > Chip-DIY trend.
> >
> > Here is only one place to look:
> > http://www.universitywafer.com/
> >
> > There's more...
> >
> > Actually, I'm not very serious about this... but if we only pretend
> > for a moment, just how much stuff would be necessary for a not overly
> > complex analog design, say up to 20-40 transistors, about the equalent
> > numbers or resistors and a few caps and a bunch of diodes. I think
> > I've heard the voices (keyboards actually) of a few sufficiently
> > knowledgeable people.
> >
> > Sure, there are some pretty hefty chemicals in use...
> >
> > But if someone think he could spare a garage-place and has been pretty
> > lucky in both gamble and love (I think an understanding wife is
> > required if one has one).
> >
> > But anyway, it would be fun to just pick up some of the knowledge in
> > this field! Please speak up!
> >
> > Cheers,
> > Magnus - has no spare space, no spare money and no wife
> >
> >

--
Scott Bernardi
sbernardi at home.net