[sdiy] Quad transistor sources

[Magnus Danielson]

From: James Patchell <patchell at cox.net>
Subject: Re: [sdiy] Quad transistor sources
Date: Sun, 27 Jun 2004 16:40:33 -0700
Message-ID: <5.2.1.1.2.20040627163523.00b22de0 at pop.west.cox.net>

> Also, if you want premium matched parts, THAT Corp ( 
> http://www.thatcorp.com ) has them in either dip or soic.
> 
> THAT300 quad matched NPN
> THAT320 quad matched PNP
> THAT340 dual PNP/NPN pairs
> 
> These parts are dialectically issolated.
> 
> These are all made on the same die, unlike the MPQ sieries, and they are
> matched in VBE and HFE.
> 
> They have a moderate bulk resistance (2 ohms), and while they will work
> for expo converters, the MAT series from Analog devices is better.

The MAT-04 gives you four transistors. The MAT-02 is basically the same
silicon but with a different metal layer hooking them up in two-and-two
(in parallel) such that temperature gradients is cancelled (to some
degree).

There is pretty simple ways to compensate out bulk resistance. With a
diode and a resistor you come part of the way, but there have been several
better solutions that goes even further.

> However, I will say, the MPQ series works pretty good for a lot of 
> applications.  And are a lot less expensive (the THAT parts run
> somewhere between 3 and 4 each, I think).

Well, it's good that there is alternatives.

Cheers,
Magnus - mailing from his "studio" and labb