A Novel Switch-Less Active Bi-Directional Phase Shifter With In–Out Impedance Equalization via Staggered Structure for K<i>u</i>-Band Applications

In this article, a switch-less vector-sum active bi-directional phase shifter (VABPS) is proposed that operates in the Ku-band and has low root-mean-square (rms) gain and phase errors with low power consumption. While conventional amplification structures address the varying input and output (IO) impedances in bi-directional operation by adding a reconfigurable matching network, this article presents the equivalent IO matching technique that eliminates the need for any additional variable matching network. The three-stack switch-less staggered structure is unveiled to facilitate identical IO impedances. This feature significantly enhances the reliability of bi-directional phase shift operations by mitigating both gain and phase errors. In addition, the optimized transformer-based hybrid coupler (HC) is adopted for generating accurate I and Q signals, followed by a biphase modulator (BM) that creates accurate 180° phase inversion of I and Q signals by resolving the nonideal effect of the HC. The proposed VABPS supports a 6-bit resolution with a phase shift range of 360° and has an rms phase error of less than 2.4° and a gain error of less than 0.55 dB in 13–15 GHz. The suggested VABPS consumes about 15.8 mW. The chip is fabricated in a standard 28-nm CMOS process and the core area is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.25\times 1.08$ </tex-math></inline-formula> mm2 including the pad.