matched transistors in chips

[Jim Patchell]

danial stocks wrote:

> Dont know if anyone already knows about these, but I just identified more
> chips in my box of weird maybe they'd be useful oneday box and came out with
> matched transistor quads!
>
> MPQ series or in surface mount MMPQ series some are straight equivalents to
> the number of the corresponding transistor ie MPQ3904 = 4x 2n3904 also
> 2907, 3906 in this fashion, there are others that seem to just have
> arbitrary numbers, and the TPQ series seems the same too from tests I've
> tried but no data.

    Somebody will have to correct me if I am wrong.  But when I investigated the
MPQ series, the spec sheet had no spec on Vbe or Hfe matching.  I was also under
the impresion that these parts were not monolithic.  The reason I had this
impression was that there is no substrate pin.  I figured they just mounted and
bonded four die.  If the die came from the same waffer, and what I deduced above
is true, you might be able to screen parts to find matched transistors.  I never
purchased parts (I do believe at least at one time Jameco had MPQ2907's).
Having four die in the same package will at least allow them to somewhat
thermally track at least.

    Let me know how useful you find these parts.

> .
> Anyway I thought I might mention this as they could be a good alternative to
> the CA3046 etc and probably loads of them lying around in old junk, hard
> drives etc if you neeed matched trans for 2am project..
> some are available on partminer etc.. I got a .pdf cant remember where which
> is a general summary of these, I'll send it to anyone who's interested..
> Cheers,
> Dan
> ________________________________________________________________________
> Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com

    -Jim