[sdiy] Matched transistors - critical parameters?

Ian Fritz ijfritz at comcast.net
Tue Feb 7 04:06:03 CET 2012

One reason sometimes given is that the newer (SMT) parts are not 
monolithic, ie the devices are not on a common substrate.  This makes the 
thermal coupling worse, although it may not matter that much.


At 07:07 PM 2/6/2012, Matthew Smith wrote:

>What are the critical parameters of old matched transistor arrays, such as 
>I've been looking at various modern ones, and the only thing that seems to 
>stand out is that the hFE of the CA3096 is somewhat higher. (I'm comparing 
>with the DMMT5551.)
>Is this a critical factor in, say, a VCF, or is it the actual matching 
>that is of greatest importance?
>Just trying to figure out what the "magic" is that makes the old parts 
>desirable over a nice little SOT-26 part costing somewhat less than half a 
>Matthew Smith
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