A 4-Element 60-GHz CMOS Phased-Array Receiver with Beamforming Calibration

A 4-element 60-GHz phased-array receiver RF front-end (RFE) employing LO-path phase-shifting configuration is presented. A wide bandwidth from 57 to 66 GHz is achieved by using multiple design techniques, including wide-band input matching network using on-chip baluns, peak-frequency staggering in the LNAs, and resonant-frequency tuning of the LC load in the first down-conversion stages. Furthermore, beamforming calibration is implemented by sequentially performing gain equalization, I/Q calibration and successive-approximation phase tuning. Implemented in a 65-nm CMOS process, each element measures gain of 21 dB and NF of 7.2 dB and IP_1dB of -21 dBm in high-gain mode while achieves IP_1dB of -12.5 dBm with gain of -2 dB and NF of 20 dB in low-gain mode. With beamforming calibration, the peak-to-null ratio of the synthesized 4-element array pattern is improved from 16.5 dB to 28.5 dB, corresponding to phase error of ±0.6° and amplitude mismatch of ±1.1 dB. The whole system consumes 320 mW from a 1.2-V supply and occupies a core area of 2.0\times 1.3 mm² excluding pads.