Design and development of a phase sensitive detector for a microwave receiver

Abstract

A phase sensitive detector employed in microwave/mm wave radiometric systems measures an output as a pure dc, proportional to the difference between the phase of the input modulated signal and a reference signal. This difference signal takes the form of a square wave, one level corresponding to a constant blackbody temperature and the other to the incoming radiation, cancelling the inherent noise of the receiver, thereby achieving a high degree of stability of the radiometer. A phase sensitive (or a synchronous) detector was designed and fabricated to be used in the microwave receiver. The phase sensitive detector was fabricated for a minimum reference signal of 3 V square wave and a minimum signal input of 75 mV with an integration time of 6 s.