Beamforming for Large, Wideband Phased Arrays: Advanced True-Time Delay and Associated Digital Control Implementations

Si-based mm-wave phased arrays have reached a significant level of maturity enabling commercial adoption. While scalability techniques to create arrays with 100s of elements haven been demonstrated, such large arrays have opened additional challenges, in particular for wideband operation. Specifically, large wideband arrays require true time delays and their digital beamforming control scheme must support fast switching among a large number of narrow beams. This presentation will address these challenges describing (1) the design of variable true time delays for mm-wave frequencies and (2) a digital beam control technique that supports fast beam switching among 10k+ beams and can be adapted to wideband, narrowband, or wide-tuning narrowband arrays. Results from a 5G scaled phased array employing a true-time delay based phase shifter and an advanced digital beam control implementation will be presented.