300-GHz-Band 4-Element CMOS-InP Hybrid Phased-Array Transmitter with 36° Steering Range
This paper presents a 300-GHz-band 4-element phased-array transmitter (TX) consisting of two types of chip, CMOS and InP HBT, to achieve a high equivalent isotropically radiated power (EIRP) and wide beam coverage. The CMOS chips include mixers and control circuits for the phased-array operation and the InP HBT chips include 300-GHz-band power amplifiers and Antipodal Vivaldi on-chip antennas. The two types of chip are connected in a flip-chip-on-chip fashion to reduce the losses. A method utilizing grating lobes is devised to overcome the limited main lobe steering range. The fabricated TX achieves a maximum EIRP of 8.4 dBm with a steering range of 36°, which is the widest among the 300-GHz-band TXs that can handle a high modulation order. The TX also demonstrates the first ever wireless data transmission with beam steering in the 300-GHz band and achieves a maximum data rate of 30 Gb/s over a 50-cm distance.