28 GHz Active Monopulse Networks with Amplitude and Phase Control and -30 dB Null-Bandwidth of 5 GHz

This paper presents an active bi-directional monopulse comparator at 28 GHz. The four inputs from the antenna quads are first divided and fed into two 2x2 TRX beamformer chips to perform sum or delta operation in either azimuth or elevation planes. A symmetrical input and output RF routing with multi-layer crossovers is implemented for wideband performance. The amplitude and phase mismatch due to both on-chip variation and off-chip routing is calibrated out with a single-point calibration at 28 GHz using fine-step VGA and phase shifters (0.2-0.3 dB/step, 5.6°/step). The measured sum port gain of 14 dB is achieved with >30 dB null-depths for a 5 GHz instantaneous bandwidth in both planes.