A Mm-Wave Phase-Time Co-Apertured Transceiver Array with Beam Squinting Mitigation for Wideband Beamforming/Spatial-Nulling

The swift progression of mm-Wave phased arrays is aimed at addressing the escalating demand for high data rates and link throughput. Simultaneously, harnessing the arrays capabilities for multifunctionality, specifically in the realms of joint communication and sensing, has stimulated growing technical interests. Both facets mandate architectures that support larger modulation/beam bandwidth (BW) and are easily scalable to large arrays. However, as phased arrays use phase shifts to approximate time delays, scaling them in instantaneous BW is fundamentally limited by the beam squinting effect, especially for large-sized arrays and wide field-of-view (FoV), resulting in challenges in realizing both wideband beamforming (BF) and wideband spatial nulling (SN). In practice, wideband SN is often more critical, as broadband spatial interference rejection is essential to protect the receiver (Rx) frontends from unknown jammers. In [1], a four-element self-interference cancellation (SIC) Rx array with 320 MHz cancellation bandwidth (BW) is proposed using baseband-to-RF impedance translation. However, this cancellation BW is solely demonstrated at 0° incident angle, where the array received signals experience no time-delay difference and thus no beam squinting. In [2], a four-element MIMO Rx array with autonomous spatial filtering is proposed. However, its phase-shifter based method cannot support BF/SN with large instantaneous BW. A 500-modulated-BW four-element baseband chain with true-time-delay (TTD) based BF/SN capabilities is proposed in [3]. However, it requires sophisticated digital signal processing to set the simultaneous BF/SN angle of arrival (AoA), an approach that is not suitable for low-latency communication. In [4], SN is achieved by setting the TTD of the array elements to point toward the interferer, instead of the desirable signal, then subtracting half of the time-aligned outputs from the other half. However, these systems do not have a degree of freedom to control the BF AoA and rely on back-end digital equalization to reconstruct the desirable BF signal, an approach that is not scalable to larger arrays and is not suitable as well for low-latency communication.