A $G$ -Band Four-Element Butler Matrix in 0.13 µm SiGe BiCMOS Technology

This paper presents the design and characterization of a 220-240 GHz four-element Butler matrix beam switching chip. It is realized in 0.13 μm SiGe BiCMOS technology. The chip features four 220 GHz amplifiers with 9 dB of gain followed by the Butler matrix core. A single-pole-four-throw (SP4T) switch is integrated to switch between the different beam directions. Finally an amplifier is used to compensate the losses of the matrix core and the switch. The chip exhibits a 2 dB of insertion loss and draws 104 mA from a 3.3 V supply. It also shows maximum phase error of 15° from the ideal phase states and less than 4 dB rms amplitude variations. The chip occupies 1.5 × 2.4 mm² silicon area.