In April and May 2007, audioXpress published a two-part article by Walter G. (Walt) Jung, noted designer and author of the IC Op Amp Cookbook and Op Amp Applications Handbook series. In this article - still being referenced to date - the author discusses audio current regulator circuits and their performance with regard to power-supply-related noise. It also details a test methodology to characterize these audio current regulation elements and circuits for sensitivity to applied voltage and demonstrate how measurement tests can help reveal which configuration is best for your power supply application.
Article Introduction by Walt Jung
This article deals with audio current regulator circuits and their performance with regard to power-supply-related noise. It describes a test methodology to characterize these audio current regulation elements and circuits for sensitivity to applied voltage. In terms of audio power supply circuitry within systems, this would be the line rejection or impedance properties. Because audio current regulators are often referred to as current sources, and the performance aspects of such for audio are basic, the article is logically entitled “Sources 101.”
But, it isn’t the last word on the topic by any means. I hope it can explain to many how to build better current regulator circuits for audio. And, most important, it definitely shows how to test these circuits, and to differentiate their performance.
Click to read the article - Part 1: Basics of Operation
Click to read the article - Part 2: Precise High Current/Voltage Operation
Click to read the article - Addendum
Two letters on the two-part series ‘Sources 101′, were published in AudioXpress, September 2007, pp. 56-60. Included along with this discussion is performance of enhanced circuit versions both in SPICE, and lab tests.
1. Walt Jung, “Regulators for High Performance Audio, parts 1 and 2,” The Audio Amateur, issues 1 and 2, 1995.
2. “LM134/234/334 3-Terminal Adjustable Current Sources,” National Semiconductor, March 2005, www.ti.com
3. Arthur D. Evans, Designing With Field-Effect Transistors, McGraw-Hill, ISBN 0-07-057449-9, 1981.
4. “The FET Constant-Current Source/Limiter,” Application Note AN103, Vishay/Siliconix, March 10, 1997, www.vishay.com
5. “J500 Series Current Regulator Diodes,” Vishay/Siliconix, July 2, 2001, www.vishay.com