A 24-28 GHz Power and Area Efficient 4-Element Phased-Array Transceiver Front-End with 21.1%/16.6%Transmitter Peak/OP1dB PAE Supporting 2.4 Gb/s in 256-QAM for 5-G Communications

This paper presents a 24-28 GHz 4-element phased-array transceiver (TRX) front-end (FE) for 5-G communications. A transformer-based embedded T/R switch is proposed which minimizes TX and RX losses to ensure high TX output power and power efficiency while maintaining a low noise figure (NF) and extremely compact chip area. The chip prototype is fabricated in a 65-nm CMOS process, the TX path achieves a record level measured 16.4 dBm/18.8 dBm OP1dB/Psat with 21.1%/16.6% peak/OP1dB PAE for each element (including T/R switch, off-mode LNA) while maintaining a minimum 4.4 dB NF in the RX path (including T/R switch, off-mode PA) at 28 GHz. Under the 64/256-QAM modulation, the TX path achieves a state-of-the-art average output power of 13.5/10.2 dBm per element (8.4%/3.5% TX PAE) with-30.8/-26.4 dB EVM and 27.8/30.1 dB ACLR at 28 GHz, making the proposed TRX FE can be effectively deployed in both base stations and user equipment for 5-G communications. The chip size of the 4-element TRX FE excluding I/O pads is only 3.4 × 1.1 mm2.