A 26.5-GHz 4x2 Array Switched Beam-Former Based on 2-D Butler Matrix for 5G Mobile Applications in 28-nm CMOS

• Published in: 2023 IEEE Radio Frequency Integrated Circuits Symposium (RFIC) pp. 49 - 52
• Main Authors: Lee, Youngjoo, Kim, Juwon, Kwon, Sungwon, Suh, Bosung, Hwang, Jun, Park, Kyutae, Chun, Dohoon, Choi, Kyujong, Choi, Hongseok, Yoo, Dongho, Min, Byung-Wook
• Format: Conference Proceeding
• Language: English
• Published: IEEE 11-06-2023
• Subjects: Antenna feeds; Azimuth; Butler matrices; Butler matrix; dual-port excitation; fast beamswitching; Mobile applications; Radiofrequency integrated circuits; reconfigurable switch; Routing; switched beamformer; Switches
• ISSN: 2375-0995
• DOI: 10.1109/RFIC54547.2023.10186171

This paper demonstrates a 26.5-GHz 2-D Butler matrix based 4×2 array switched beamformer. By using a 2-D Butler matrix, feed lines between IC and antennas are uniform, which is a critical problem in an integrated Butler matrix for a 1- D array since it requires complex phase matched routing on PCB. A proposed switched beamformer consists of a signal distribution IC and two switched beamformer ICs. Reconfigurable switches with a function of power divider/combiner are integrated for additional beam patterns. The proposed switched beamformer can generate total 22 beams, which cover a whole scan angle with a low gain variation. Measured beam patterns show that the proposed switched beamformer can cover any 3-D spatial angle of ±44° in azimuth and ±43° in elevation even with a low spatial beam resolution. To our knowledge, this is the first 2-D array switched beamformer based on the Butler matrix in millimeter wave bands.