A 4-element 60-GHz CMOS phased-array receiver with transformer-based hybrid-mode mixing and closed-loop beam-forming calibration

A 4-element 60-GHz phased-array receiver employs transformer-based hybrid-mode mixing featuring high linearity and high gain. Closed-loop beam-forming calibration is achieved by sequentially performing gain equalization, I/Q calibration, and successive-approximation phase tuning. Implemented in 65nm CMOS, each element measures NF of 6.5dB, gain of 20dB and IP_1dB of -12.5dBm. With the proposed beam-forming calibration, the peak-to-null ratio of the array pattern is improved from 16.5.dB to 28.5dB, corresponding to phase error of ±0.6° and amplitude mismatch of ±1.1dB.