GaAs Monolithic Balanced Mixer for C Band Direct Demodulation Receiver

This paper describes the performances of a GaAs monolithic balanced mixer for C band direct demodulation receiver front-end. Direct demodulation implies design choices, such as the use of Schottky diodes and a 180° balanced configuration. The coupler used is a monolithic solution of a rat-race hybrid, synthetised with lumped element low-pass and high-pass networks. The circuit, with a size of 1.5 × 2. mm2, exhibits a conversion loss of less than 7.5 dB for signal and LO frequencies from 6.5 GHz up to 9 GHz, and for IF frequencies from 10 to 100 MHz.