This article introduces a power-efficient and lowcost CMOS 28-GHz phased-array beamformer supporting fifthgeneration (5G) dual-polarized multiple-in-multiple-out (MIMO) (DP-MIMO) operation. To improve the cross-polarization (crosspol.) isolation degraded by the antennas and propagation, a power-efficient analog-assisted cross-pol. leakage cancellation technique is implemented. After the high-accuracy cancellation, more than 41.3-dB cross-pol. isolation is maintained along with the transmitter array to the receiver array. The element-beamformer in this work adopts the compact neutralized bi-directional architecture featuring a minimized manufacturing cost. The proposed beamformer achieves 22% per path TX-mode efficiency and a 4.9-dB RX-mode noise figure. The required onchip area for the beamformer is only 0.48 mm 2 . In over-the-air measurement, a 64-element dual-polarized phased-array module achieves 52.2-dBm saturated effective isotropic radiated power (EIRP). The 5G standard-compliant OFDMA-mode modulated signals of up to 256-QAM could be supported by the 64-element modules. With the help of the cross-pol. leakage cancellation technique, the proposed array module realizes improved DP-MIMO EVMs even under severe polarization coupling and rotation conditions. The measured DP-MIMO EVMs are 3.4% in both 64-QAM and 256-QAM. The consumed power per

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This article introduces a wirelessly powered phasedarray transceiver for fifth-generation (5G) relay systems. To realize the battery-less relay operation, 24-GHz wireless power transfer (WPT) is employed. This relay transceiver consists of the proposed vector-summing backscatter for Transmitter (Tx) and a passive phase-shifting self-heterodyne Receiver (Rx) with a rectifier for Rx and WPT. The receiver generates dc power from the 24-GHz WPT signal, which is also used as a local oscillator (LO) signal to down-convert the 28-GHz 5G modulated data to a 4-GHz IF. The vector-summing backscatter up-converts the 4-GHz IF signal to 28-GHz using a 24-GHz LO signal while working as a 360 • phase shifter with a 7-bit resolution. Both transmitter and receiver operate only using the generated power from the 24-GHz WPT. The chip area of the eight-path transceiver is 1.8 mm 2 and the transceiver is mounted on a 32-element phased-array antenna board. This module generates 3.1-mW dc power from 6.7-mW/cm 2 received power density at 24 GHz. The transmitter achieves a −2.2-dBm measured saturated equivalent isotropically radiated power (EIRP) and supports a −30 • to +30 • beam range. The measured error vector magnitude (EVM) values are −27.5 dB for Tx mode and −31.3 dB for Rx mode with a 400-MHz 64-QAM orthogonal frequency division multiple access (OFDMA)-mode signal (5G new radio (NR), MCS 19). The power consumption for each path is 0.03 mW in both Tx and Rx modes.

This article introduces a four-element 300-GHzband bi-directional phased-array transceiver (TRX). The TRX utilizes the same antenna, signal path, and local oscillator (LO) circuitry to operate either in transmitter (TX) mode or receiver (RX) mode. The TX mode adopts the outphasing technique to increase the average output power for higher order modulation schemes by utilizing the two mixers that are connected directly to the antenna in a mixer-last fashion. The two signal paths also enable the canceling of the LO feed-through (LOFT). The RX mode also benefits from the LOFT cancellation technique to suppress the LO emission, which is a common issue of the mixer-first RXs. The RX has a separate Hartley operation mode to reject the image signal coming from the TX. The TRX chip was implemented using CMOS 65-nm process, and a four-element phased array was implemented by stacking liquid crystal polymer (LCP) flexible printed circuit boards (PCBs). The stacked structure provides the required narrow antenna pitch at the 300-GHz band. The measured beam angle range is from Manuscript

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