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Proceedings Paper

Current loop: a measurement circuit topology alternative to the Wheatstone bridge
Author(s): Karl F. Anderson
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Paper Abstract

An analog measurement circuit topology is presented that significantly outperforms the Wheatstone bridge in many measurement and control applications. The initial output level can be simply adjusted to zero volts. Using active subtraction, the topology can provide greater measurement accuracy than the Wheatstone bridge, especially for measurements in difficult environments. When compared to a Wheatstone bridge arrangement of variable impedance elements, some of the advantages of this measurement circuit topology are: double and electrical output for the same sensor element power dissipation, the quantity of sensor elements may be reduced by one half, nearly 6 db improvement in single-to-noise ratio, ratiometric operation, even random lead wire variations are typically irrelevant, linear electrical output even for large changes in a single impedance element, fewer wires from the observing electronics to impedance elements, transducers can have any number of electrical elements (each with different initial impedances), outputs are presented from each individual sensor impedance element as well as an aggregate output from any subset of elements, sensor calibrations can be any function of each individual sensor element change, and temperature at the various monitored impedances can be indicated without additional lead wires.

Paper Details

Date Published: 6 June 1997
PDF: 16 pages
Proc. SPIE 3042, Smart Structures and Materials 1997: Smart Sensing, Processing, and Instrumentation, (6 June 1997); doi: 10.1117/12.275725
Show Author Affiliations
Karl F. Anderson, Valid Measurements (United States)

Published in SPIE Proceedings Vol. 3042:
Smart Structures and Materials 1997: Smart Sensing, Processing, and Instrumentation
Richard O. Claus, Editor(s)

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