In electronic
signal processing
Signal processing is an electrical engineering subfield that focuses on analyzing, modifying and synthesizing ''signals'', such as audio signal processing, sound, image processing, images, and scientific measurements. Signal processing techniq ...
, a square law detector is a device that produces an output proportional to the square of some input.
[''IEEE Std. 100 Authoritative Dictionary of Standards Terms Seventh Edition'', IEEE, 2000, ,''Square law detection''] For example, in demodulating radio signals, a semiconductor
diode
A diode is a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other.
A diode ...
can be used as a square law detector, providing an output current proportional to the square of the amplitude of the input voltage over some range of input amplitudes.
[H. C. Torrey, C. A. Whitmer, ''Crystal Rectifiers'', New York: McGraw-Hill, 1948, pp. 3 - 4](_blank)
/ref> A square law detector provides an output directly proportional to the power of the input electrical signal.
References
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Signal processing