Resistive diode microwave mixers used as phase comparators

Phase comparators are fundamental blocks of differentially coherent demodulators. In particular, when a 4S-DCPSK on board demodulator with direct r.f. demodulation is considered, the phase detector be haviour strongly influences demodulator performance. In this case, an analysis of output-voltage variations caused by input-power-level variations and circuit nonideal characteristics is rdequired to determine the impairment of the whole demodulator assembly. Single balanced resistive diode mixers used as phase detectors are considered becaurse they are the most common type of microwave mixers, but results may also be representative for other mixer types.