mmWave Spatial-Temporal Single Harmonic Switching Transmitter Arrays for High Back-Off Beamforming Efficiency

• Published in: IEEE transactions on antennas and propagation Vol. 70; no. 9; pp. 8122 - 8136
• Main Authors: Yu, Zhehao, Lu, Xuyang, Gu, Changzhan, Venkatesh, Suresh, Mao, Junfa
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna arrays; Array signal processing; Arrays; Beamforming; boldsymbol Back-off efficiency; Circuit design; Computer architecture; Harmonic analysis; Millimeter waves; phased array; Phased arrays; Power amplifiers; power amplifiers (PAs); Power system harmonics; spatial-temporal modulation; Switching; time-modulated array (TMA); Transmitters
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2022.3177551

This article presents a spatial-temporal single harmonic switching (STHS) transmitter array architecture with enhanced efficiency in the power back-off (PBO) region. STHS is an electromagnetic circuit co-designed and jointly optimized transmitter array that realizes beamforming and back-off power generation at the same time. The temporal dimension is originally added in STHS to achieve back-off efficiency enhancement, which can be combined with conventional PBO enhancement methods such as Doherty amplifiers and envelope tracking. The design is validated through a simulation of a two-stage power amplifier (PA) in 65-nm CMOS at 77 GHz, which achieves a peak drain efficiency (DE) of 24.2%, a 22% DE at 3 dB PBO, 16% DE at 6 dB PBO, and 10.2% at 9 dB PBO. The efficiency exhibits a 57% improvement at 3 dB PBO, 100% improvement at 6 dB PBO, and 190% improvement at 9 dB PBO compared with class A/B amplifiers.