An 8 x 8 Butler Matrix in 0.13-μm CMOS for 5-6-GHz Multibeam Applications

This paper presents a miniature 5-6-GHz 8 x 8 Butler matrix in a 0.13-mu m CMOS implementation. The 8 x 8 design results in an insertion loss of 3.5 dB at 5.5 GHz with a bandwidth of 5-6 GHz and no power consumption. The chip area is 2.5 x 1.9 mm(2) including all pads. The 8 x 8 matrix is mounted on a Teflon board with eight antennas, and the measured patterns agree well with theory and show an isolation of > 12 dB at 5-6 GHz. CMOS Butler matrices offer a simple and low-power alternative to replace eight-element phased-array systems for high gain transceivers. The applications areas are in high data-rate communications at 5-6 and at 57-66 GHz. They can also be excellent candidates for multiple-input-multiple-output systems.