D-Band Branch-Line Coupler Using 0.18 μm CMOS Technology for 6th Generation Wireless Communication

In this article, a D-band branch-line coupler in the form of a microstrip line is designed in 0.18 μm CMOS technology. A microstrip line ensures that the signal is transmitted at the designed frequency and realizes a stable signal output with a 90° phase difference. At the end of the paper, a practical verification is also carried out. The bandwidth of the proposed branch coupler is measured from 149 to 158 GHz. The input signal can be divided into two balanced signals with a phase difference of 90 ° . The lowest simulated S21 transmission loss is 4.8 dB and the measured S31 coupling loss is 4.47dB. The wafer size is 1.2 × 0.5 mm², which is suitable for application in the design of the sixth-generation mobile communication system.