A 24–32 GHz Bidirectional Variable-Gain Phase Shifter Using a Novel Quadrature Generator and Dual-Function Bidirectional Amplifier With Phase Compensation

Abstract

This paper presents a 6-bit bidirectional variable-gain vector-summing active phase shifter (BVG-AVSPS) in TSMC 65nm CMOS technology. The proposed BVG-AVSPS consists of a novel bidirectional quadrature generator, four dual-function bidirectional amplifiers and two input/output matching networks. The proposed hybrid-based quadrature generator achieves low orthogonal amplitude and phase mismatches over a wideband with bidirectionality. Dual-function bidirectional amplifiers are employed to achieve either vector modulation or gain control functions in different operational directions. To improve the phase shifting accuracy during gain tuning, compensation transistors are employed in the dual-function bidirectional amplifiers to minimize additional phase variation. The proposed input/output networks based on L-type coupled inductors ensure proper impedance matching for both input and output in TX and RX modes. For both TX and RX modes over 24 GHz~32 GHz, the measured RMS phase and gain errors are $1.25^{\circ } \sim 2.4^{\circ }$ and 0.42 dB~0.56 dB throughout 12.3 dB gain tuning range, respectively. With the help of the compensation transistors, measured phase variation is less than ±2.1° during output gain tuning. The core area of proposed BVG-AVSPS is $625~\mu $ m $\times 355~\mu $ m.