An Ultracompact 6-bit Phase Shifter Using Active Balun Embedded Vector-Sum Core

Abstract

This letter introduces an ultracompact, high-resolution X-band active phase shifter (PS) featuring an active balun embedded vector-sum (VS) circuit. With a compact size of $0.22~\text {mm}^{2}$ , it utilizes a novel structure that integrates the balun within the vector summing circuit, eliminating the need for extra baluns to generate a differential signal. It also employs a small-size ribbon-type inductor for input matching of in-phase (I) and the quadrature-phase (Q) generator. The proposed PS has high accuracy due to both a low IQ error caused by the constant input impedance of the VS circuit regardless of the phase changes and high-resolution digital-to-analog converters (DACs). The chip is manufactured using a 65-nm CMOS process, achieving a high phase resolution of 5.625° and exhibiting low root-mean-square (rms) phase and gain errors of less than 1.14° and 0.34 dB within 7.15–8.9 GHz. It demonstrates a peak gain of −1.3 dB and has a power consumption of 10.38 mW.