Peak-amplitude detector for sinusoidal signals

A circuit technique is proposed for detecting the peak amplitude of a sinusoidal signal using Pythagoras's law without requiring a simultaneous equal-amplitude quadrature signal. The number of four-quadrant multipliers required is only two.

[1]  Frank Doorenbosch.  An Integrated Wide-Tunable Sine Oscillator , 1975, 1975 First European Solid State Circuits Conference (ESSCIRC).

[2]  R. Barker.  Phase-shifting technique without reactive components , 1978 .