A reconfigurable balanced loaded‐line phase shifter based on slot line

Abstract

A reconfigurable balanced phase shifter is designed in this paper, which can achieve stable differential mode (DM) phase shift and high common mode (CM) suppression. The proposed balanced phase shifter is mainly composed of micro strip/slot line transition structure and π-shape slot line. The U-shaped micro strip line and the stepped impedance slot line are employed to form the differential input and output ports, which can make the DM response and the CM one are independent. By switching the PIN diode on or off, a stable 180° DM phase shift difference is achieved between two states. In order to verify the design, a 180° balanced phase shifter with a central frequency of 4.7 GHz was simulated and fabricated. DM insertion loss of the design is 1.1 dB, DM phase deviation range is ±5°, 10 dB DM impedance matching fractional bandwidth is 45%, and phase fractional deviation bandwidth is 42%. Meanwhile, the CM rejection can reach about 35 dB. The simulation and measurement are in good agreement with the theory.