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Optimization of the Amplified-Diode Bias Circuit for Audio Amplifiers

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An economic enhancement to the conventional "amplified diode" bias circuit is presented for use in power amplifier circuit topologies which do not allow precise, temperature invariant control of the operating current of the bias circuit. In essence, the modification minimizes the sensitivity of the derived bias voltage to changes in operating current without compromising the desirable temperature tracking properties when thermally bonded to the complementary follower output cell.

JAES Volume 32 Issue 1/2 pp. 31-33; February 1984
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Scott Dorsey
Scott Dorsey

Comment posted May 15, 2020 @ 15:40:51 UTC (Comment permalink)

This is a rather interesting discussion of the very simple topology of the "amplified diode" circuit which is used to provide a constant voltage between two floating points.  Such a thing is very useful for setting the bias of an amplifier output stage, and the author shows that the addition of a single resistor can make for a stiffer and more stable voltage reference.  Note that the basic topology described here has since been replaced with more sophisticated integrated voltage references but the author's mathematical analysis is in great part why we have such IC references today.

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