An eight-way phased-array TRX front-end with RF phase shifting and on-chip transmit/receive switching is implemented in 28-nm CMOS. The TX P_1dBout and RX noise figure (NF) are 10 dBm and 6.8 dB, respectively. The active phase shifter shows less than 5° phase resolution and amplitude errors within ± 0.35 dB. The 9.6-mm²chip consumes 231 mW in RX and 508 mW in the TX mode from a 0.9-V supply. When combined with PCB antennas, a ±46° scan angle is obtained with <;0.4 dB peak-to-peak gain ripples without calibration. We also present an approach to express the noise performance of a phased-array receiver in terms of the effective isotropic NF, as an extension to the NF, which is only defined for a two-port system.