A 0.8-6 GHz True-Time-Delay Beam-Nulling Receiver Front-End

Hybrid beamformers utilize spatial filtering before the analog-to-digital converter for improved dynamic range performance while also allowing flexibility from digital spatial processing. Using true-time-delays (TTD) in the analog beamforming section of the hybrid enables directivity control for large fractional bandwidths. However, TTD beamforming is not ideal for filtering wide band interferers since the null directions still change with frequency. This paper reports the first published TTD beam-nulling RF receiver front-end for wideband spatial filtering. The receiver implements TTDs with the recently introduced resampling method. The signal inversion required for beam-nulling is implemented on-chip with clock tuning outside of the signal path. The receiver supports an instantaneous beam-nulled bandwidth of 1.6 GHz across the 0.8-6 GHz frequency range, reaching a 100% fractional bandwidth at the low end. The prototype was implemented in a 22-nm FD-SOI CMOS process.