A 60-GHz Positive-Feedback-Based Transmitter Front-End with 22.8% PAEmax in 28-nm Bulk CMOS for Inter-Satellite Communications

This paper presents a power and area efficient 60-GHz RF-beamforming transmitter front-end (TXFE) in 28-nm bulk CMOS for inter-satellite communications. It consists of a vector modulator (VM) for phase shifting and gain control, a driver, and a power amplifier (PA). By applying a gain-boosting technique based on positive feedback, the number of cascaded stages is minimized, which reduces the total power consumption and enables chip area saving. Measurement results demonstrate a peak gain of 25.2 dB at 61 GHz, with a 22.6% maximum power-added efficiency (PAEmax) and a 12.4-dBm saturated output power (Psat). The minimum stability factor (Kf) is 1.5. Additionally, at 61 GHz, this TXFE supports 2.4-Gbps SC/400-MHz OFDM 64 QAM, achieving 5.6/5.3% Error Vector Magnitude (EVM) and -31.4/-30.8-dBc Adjacent Channel Power Ratio (ACPR), at 5.1/3.7-dBm output power (Pout) with 7.4/5.2% TX efficiency. The core area is 0.66×0.27 mm².