[sdiy] mached transistors

[Tom May]

"Theo" <t.hogers at home.nl> writes:

> Only the pairs have to be matched, the closer the better.
> For a ladder its enough to have the top and bottom pairs matched.
> But matching all pairs does give slight a improvement.

Certainly matching the transistors in the top and bottom pairs is
necessary for minimizing control voltage feed-through, but what does
matching the other pairs improve?

> Using LM3046 ICs is also an alternative,
> each IC contains one matched pair and 3 separate transistors.
> 
> Theo
> 
> 
> 
> From: Terje Winther <terje.winther at notam02.no>
> 
> > Hello,
> > I am measuring some transistors to get "mached transistors" needed for
> some
> > VCFs (moog-ladders) and VCAs.
> > How close do they have to be to be called "matched"?
> > totally equal? 1% apart? 2% 3-5%?
> > Also, for the moog-ladder filters; do they have to be matched between the
> > ladder "staps", or is it enough to have the two transitors of each "step"
> > to be matched?
> >
> >
> > tw.  :)
> >
> >

Tom.