Reconfigurable True-Time-Delay Phase Shifter Using Defected Ground Structure With Loaded Stubs

This letter presents a novel and high-performance reconfigurable true-time-delay (TTD) phase shifter. A compact dumbbell-shaped defected ground structure (DGS) is introduced to achieve a certain amount of TTD phase shift and low-transmission insertion loss. The p-i-n diode is used to control the on and off modes of the DGS unit. To enhance the impedance matching in both on and off modes, additional matching circuits are designed using microstrip stubs. Moreover, to realize a larger phase shift value, a six-unit DGS-reconfigurable TTD phase shifter is reported. The result reveals that the operating bandwidth ranges from 0.5 to 2.5 GHz, with a maximum phase shift of 120° and an insertion loss of less than 1 dB across the entire bandwidth. A prototype is simulated, fabricated, and successfully measured, and the measured results show excellent agreement with the simulation ones.