[sdiy] Speaking of OTAs/Matched Pairs????

[harry]

Picture the cost of testing every chip... the question is do you pay for
a guarantee of performance, or shoot the dice. Many designs just care
that there is a TRANSISTOR in that package....

Its like the generic brand food cans... Often they are over production by the
same national brands, who don't want to compete with themselves. Why queer
your own market?

The only problem would be if you happened to get a whole sh!tty batch at the same
time.

Or you could do like I do, and use some ridiculous price premium brand... can
you say AD ???

H^) harry

patchell wrote:

> Colin Fraser wrote:
>
> > > -----Original Message-----
> > > From: owner-synth-diy at node12b53.a2000.nl
> > > [mailto:owner-synth-diy at node12b53.a2000.nl]On Behalf Of Jim Patchell
> > > Sent: 12 March 2001 21:08
> > > To: Kevin Peek
> > > Cc: synth-diy at node12b53.a2000.nl
> > > Subject: Re: [sdiy] Speaking of OTAs/Matched Pairs????
> > >
> > >     Arrays like the CA3046 are actaully pretty well matched.  Even on
> > > the speck sheet, typical matching is 500uV (worst case is 5mV).  The
> > > CA3086 does not garentee any matching (it is the same part, just not
> > > tested).
> >
> > If the CA3086 is just a 3046 without matching guaranteed, isn't that likely
> > to mean that matching is guaranteed to be outside the spec for the '46 ?
> >
> > i.e. 3086 = 3046 that failed the matching test
> >
> > Colin f
>
>     That's where FUD comes into play (Fear Uncertainty and Doubt).  You will
> gamble.  They could have failed, they could have just never been tested.  You
> don't know.  Even with the CA3046, the typical Vbe matching is 500uV, with the
> worst case being 5mV.  All this means is that in some sample, most of the parts
> were around 500uV.  I have seen designs fail because the first production run
> was done with a batch of parts that were typical, the next batch had a wider
> distribution.
>
> --
>  -Jim
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> * Visit:http://www.silcom.com/~patchell/
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