[sdiy] moog high pass flter - Transistor Matching

[Ian Fritz]

Um, well you take one and measure the other n-1 against it.  Then pick the 
good pairs by comparing the numbers, just as if you had measured them singly.

The advantage would be that you are using a differential measurement and 
therefore get better resolution.  You could in principle use a 3 1/2 digit 
DVM to determine offsets in the microvolt range.  It would be quite 
difficult to do this well with the .56 V background you have in a single 
measurement.

   Ian


At 08:49 PM 12/9/2002, Scott Bernardi wrote:
>Although what you describe would work to compare two Vbe's, I'm not sure
>how useful it would be to know just the mismatch between two
>transistors.  If you had n transistors to work from, you'd have to
>potentially make 2^(n-1) comparisons. Probably not bad if you were only
>looking for one matched pair.
>If you record the values of the Vbe's, then you make one measurement for
>each transistor, and you compare values to see which pairs can go
>together.