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Mm-wave phased-array receivers (RXs) operating in complicated electromagnetic environments often suffer from spatially diversified interference, which leads to saturation and non-linear distortion in the RXs. One commonly used approach to mitigate this issue is the application of sidelobe suppression methods using window functions 1, 2, which comes with a drawback of array gain reduction. Alternatively, spatial notch filters are proposed, which can generate a spatial notch to undesired in-band blockers. This can be achieved at baseband and intermediate frequency (IF) stages where the blocker received in each channel is amplified, downconverted, and processed 3, 4. However, the blocker handling capability is limited by the linearity of the downconversion mixers and subsequent IF circuits, thereby a power-hungry, highly linear mixer is in demand. Another approach is to suppress the blocker in RF chains, but this approach imposes limitations on the scalability of phased-array RXs since each element requires an individual spatial notch filter and a symmetrical layout 5. In this work, we demonstrate a beam-pattern null-steering (BPNS) technique for mm-wave phased-array RXs, which (1) suppresses in-band blockers before the mixer, (2) eliminates the need for lossy attenuators or power-hungry variable-gain amplifiers (VGAs) in each RF channel, and (3) supports higher scalability. Also, a beam-tracking (BT) method is developed to timely detect the incident angles of blockers, as well as that of the desired signal.
Yu et al. (Sun,) studied this question.