Multiplier/detector for SAW spectrum analysers

Surface-acoustic-wave (SAW) spectrum analysers such as compressive receivers can be used to perform real-time, wideband, transform-domain correlation. A major practical difficulty in such systems is the design of a bilinear analogue multiplier with wide input and output bandwidths and good dynamic range. A simple circuit is presented for such a multiplier, and the circuit performance as a square-law detector and correlator is illustrated.