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Review of Jim Williams: AN23 Micropower Circuits for Signal Conditioning

Download AN23 Micropower Circuits for Signal Conditioning (1987, Linear Technology, 24 pages, 2.1 MB pdf file)

AN23 discusses several examples of micropower circuits: Sensor signal conditioning for temperature sensors and strain gauges, micropower A/D converters and also micropower switching regulators. One application that is discussed in much detail is a 10kHz voltage to frequency converter with a linearity of 0.02% and a maximum current consumption of only 145uA (see p.10 - 13 and also Box Section A, p.18 -20). Williams shows how he developed the circuit in several steps until he reached its extraordinary performance. By the way, this is the famous "Zoo Circuit". If you have access to Analog Circuit Design, you can find its very interesting history (together with more technical details) in chapter 23, p. 215. Box Section B (Sampling Techniques and Components for Micropower Circuits, p. 21) and Box Section C (Parasitic Effects of Test Equipment on Micropower Circuits, p.23) of AN23 are also interesting.

If you want further information about micropower circuits you should also have a look at The Art of Electronics, chapter 14 Low Power Design (p. 917). But please note that both AN23 and The Art of Electronics are from the late 1980s: Both contain very interesting design ideas, but the specified ICs may not be available any longer, or you may get ICs with even better performance today.

You may also be interested in some other Application Notes by Jim Williams.

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