A compact, monolithic radiofrequency demodulator-modulator for 64-QAM digital radio links

The design, fabrication, and performance of a GaAs monolithic radiofrequency demodulator with phase and amplitude trimming in the quadrature coupler and balanced mixers in the 5.9-8.5 GHz range is described. This circuit includes amplitude and phase trimming circuits, two single balanced mixers, couplers, and a quadrature phase comparator. The design is such that the same chip can be used either as a direct 64 QAM (quadrature amplitude modulation) demodulator or a modulator. The small chip size is 2.7 mm*3.65 mm. >