A 5G 28-GHz Common-Leg T/R Front-End in 45-nm CMOS SOI With 3.7-dB NF and −30-dBc EVM With 64-QAM/500-MBaud Modulation

This paper presents a 28-GHz common-leg phased-array front-end in 45-nm CMOS silicon on insulator with transmit and receive capabilities. The design alternates cascode amplifiers with passive switched-LC phase-shifter cells to result in 5-bit phase control with an rms phase and gain error <;4° and <;0.8 dB, respectively, at 24-30 GHz, over 32 phase states. The front-end has 2- and 3-bit variable gain amplifiers with 7.5-dB total gain control, without affecting the system noise figure (NF). Two low-loss high-linearity single-pole double-throw switches are used to switch between transmit and receive modes. In the receive (Rx) mode, the measured gain, NF, input 1-dB compression point (P1dB), and input third-order intercept point are 16 dB, 3.7 dB, -15 dBm, and -7 dBm, respectively, with 54-mW dc power consumption. In the transmit (Tx) mode, measurements show 16.5-dB gain, an output P1dB of 8 dBm, and an output IP3 of 16 dBm with 100-mW dc power consumption. The error-vector magnitude and adjacent-channel-power-ratio measurements demonstrate quadrature phase-shift keying, 16-quadrature amplitude modulation (QAM), 64-QAM, and 16-QAM orthogonal frequency-division multiplexing modulations with several symbol-rates reaching up to 8 Gb/s data-rate for both the Rx and Tx modes at 2- and 5-dB back-off. The application areas are in fifth-generation phased arrays requiring high-linearity receivers and using external front-end modules for added transmit power.