AW: [sdiy] Having a hard time finding the chips you want - roll y our own!

[Czech Martin]

We had a lot of discussion about the Moog ladder recently,
even into the finest details. I think we should not forget
that integrated transistors have some disadvantages, too.
E.g. parasitic capacitance. 
And there is latch up, something you will never experience
in a discrete circuit. Lots of parasitic effects.
Basically it is not much fun to design a circuit as
integrated device, because of these parasitics.
This does not apply for matching and equal temperature, 
of course, this is really the big bonus feature of integration,
and the only one I can think of (for 10 analog transistor
circuits).
So perhaps some care is needed
to develop a good integrated clone of a discrete original.
It would be fascinating, no doubt!

Perhaps it would be better to concentrate on originals
that where integrated from the beginneng, ie. SSM and
CEM designs, but then we have patent issues, as well as
reverse engineering effort.

But after wafer out we have bonding and packaging issues.
We don't want to place test needles on wafer every time
we want to play, do we? (Hey, like in the old self driven
"crystal detector" radios, ... wait a minute, I have to
make a junction ....

Very often research labs do not package their parts at all,
they actually never solder something.


m.c.


> -----Ursprüngliche Nachricht-----
> Von: Theo [mailto:t.hogers at home.nl]
> Gesendet: Mittwoch, 29. August 2001 11:50
> An: Czech Martin; 'Magnus Danielson'; synth-diy at dropmix.xs4all.nl
> Betreff: Re: [sdiy] Having a hard time finding the chips you 
> want - roll
> your own!
> 
> 
> I know one list member that actually has cleanroom access and 
> a "free" waver
> every 2 months.
> Tried to get him make moog ladders, but think in the end he 
> did only dual
> trannies for a 303 clone.
> Say H are you still on the list?
> If anybody knows about DIY ICs its you, lets hear it!
> 
> Ain't there any studends on the list following a IC design practicum.
> Try convince your prof that you _need_ some exstra wavers.
> If you don't know what to do with  them, there are 
> suggestions enough on
> this list.
> (3 tranny OTAs ?, moog ladders?, expo with temp compensation 
> in IC form?)
> 
> Theo
> 
> 
> 
>