Time-delay array beamforming for millimeter-wave IoT systems

This chapter discusses a scalable mixed-signal architecture for beamforming in time-delay arrays, where the time delays are realized by delaying the sampling clock of the receiver analog-to-digital converters. We derive the requirements on the timing correction and show how they are feasible in standard CMOS manufacturing processes. We then evaluate the impact of timing quantization of the array performance and compare the bit error rate (BER) performance of the proposed approach to phase arrays. For the same number of antennas, the BER of such an array is shown to be several orders of magnitudes lower than that of a phase array, especially at high fractional bandwidths. This chapter concludes by showing how a sub-picosecond requirement on time-delay generation for the beamformer is addressed using an antenna grouping strategy based on a hybrid architecture of a time and phase arrays. This architecture can relax the time correction requirements while enabling large arrays and fractional bandwidths with a modest BER penalty. Extensive simulations are used to evaluate the impact of antenna group sizes on the overall BER of the millimeter wave antenna system.