Wideband input impedance invariant active phase shifter for millimeter-wave 5G communication

Abstract

In this study, we propose a wideband input impedance-invariant active phase shifter tailored for millimeter-wave 5G communication systems. The compensation for high path losses inherent in the millimeter-wave frequency band necessitates beamforming technology, underscoring the importance of an active phase shifter capable of controlling phase and gain. To mitigate input impedance variations in the active phase shifter, we propose a Miller capacitor neutralization technique. This ensures a consistent input impedance across all phase and gain states, effectively resolving IQ imbalance issues caused by input impedance variations. Consequently, it minimizes the degradation of maximum available gain per unit power. Moreover, we address bandwidth limitations problem in the Gilbert cell-based vector adder by proposing an inter-stage CLC π-network. Inserting this network between common source and common gate stages introduces a complex pole in the transfer function, creating gain peaking at higher frequencies and extending the bandwidth. Additionally, low-power circuit biasing significantly reduces the power consumption of the active phase shifter.