Low power consumption vector-sum phase shifters using zero-pi amplifiers for millimeter-wave beamforming

This paper presents a novel circuit configuration of a vector-sum phase shifter for millimeter-wave beamforming to lower power consumption. The proposed configuration has a 90-degree hybrid circuit and two zero-pi amplifiers. The zero-pi amplifiers have a zero-pi phase switching function and a variable amplitude control function. The zero-pi phase switching function is achieved by switching two input ports of a transformer in front of a differential amplifier with a single-pole dual-throw (SPDT) switch. This makes it possible to approximately halve the active circuit scale of a conventional four-phase branch phase shifter. We demonstrate 60- and 28-GHz CMOS phase shifters using the proposed configuration. The 60-GHz phase shifter has a 6.6 dB average insertion loss at 58 GHz with a 5.0-mW average power consumption for a 1.2 V supply voltage. Moreover, the 28-GHz phase shifter has a 6.6 dB average insertion loss at 28 GHz with a 2.3-mW average power consumption for a 0.5 V supply voltage.