Evaluation of a 40-nm CMOS Process 105-to-145-GHz Differential Wilkinson Coupler

In this paper, a method for evaluating D-band differential Wilkinson couplers is proposed: a 4-port differential network analyzer is used to evaluate a 6-port differential Wilkinson coupler by combining two pairs of RF differential input ports (4 ports in total) into two ports using two baluns. To evaluate the proposed method, a differential Wilkinson coupler operating from 105 to 145 GHz was fabricated using a 40 nm CMOS process, and simulation and measurement results were compared. 4-port measurement results up to 130 GHz are in good agreement with simulation results.