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Draft:Clegg integrator

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  • Comment: Currently relies on only one source, which is primary. msk 18:27, 27 May 2026 (UTC)

The Clegg integrator is a nonlinear analog integrator equipped with a reset mechanism, used in feedback control systems. It was proposed by J. C. Clegg in 1958 as a modification of the conventional linear integrator.[1]

Schematic of a Clegg integrator

Description

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The Clegg integrator behaves like an ordinary linear integrator, except that it resets its output to zero whenever its input crosses zero.

The circuit of a Clegg integrator consists of resistors R, Rd, and Rs, two capacitors C, four diodes, and two operational amplifiers. It is assumed that Rd≪R. Let Vin denote the input voltage of the circuit and Vout the output voltage. As long as Vin does not cross zero, the output Vout is proportional to the integral of Vin. However, the integral is reset as soon as Vin=0. Denoting by ti the most recent instant at which Vin=0, we then have:

Vout(t)=−12RC∫titVin(s)ds

Use

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In control theory, controllers with an integral action on the control error (for example PID controllers) suffer from windup phenomena when the actuator saturates (a valve at its limit, maximum voltage, etc.). This is known as the windup problem. By replacing the conventional linear integrator with a Clegg integrator, the integral term is reset to zero at each zero-crossing of the error, which improves the performance of the controller.

References

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  1. ↑ Clegg, J. C. (March 1958). "A nonlinear integrator for servomechanisms". Transactions of the American Institute of Electrical Engineers, Part II: Applications and Industry. 77 (1): 41–42. doi:10.1109/TAI.1958.6367399. ISSN 0097-2185. Retrieved 2026-05-26.