A Frequency Reconfigurable Phased-Array Front-End with Enhanced Image-Rejection and High-Resolution LO Phase Shifter for 5G FR2 n258/n260/n261 Bands

This paper presents a frequency reconfigurable phased-array front-end covering 5G FR2 n258/n260/n261 bands in 65-nm CMOS. The front-end adopts a local-oscillator (LO) phase-shifting architecture with a frequency reconfigurable power amplifier (PA) and low noise amplifier (LNA) to realize multi-band operation while relaxing LO phase shifter bandwidth requirements. Benefiting from the proposed passive and active frequency-reconfigurable matching network, an image-rejection ratio (IMRR) of 22.8-43.4 and 37.3-57 dBc can be achieved for TX and RX, respectively. To enhance the phase resolution of the LO vector-summing phase shifter, a layout-flexible transmission line phase shifter as well as PMOS varactors are introduced, resulting in <1° RMS phase error with 7-bit phase control. The measurement results show that the front end can delivers 17.6 and 16.4 dBm saturated output power, 19% and 12.2% peak power added efficiency, and a minimum noise figure of 6.5 and 8.1 dB at 27 and 37 GHz, respectively.