Magnetic-Free Isolators Based on Time-Varying Transmission Lines

Abstract

Two magnetic-free reconfigurable isolators based on a doubly balanced gyrator (DBG) are designed in this paper. One of the isolators is a single-ended transmission isolator (STI), which uses two matching resistors to absorb the signal transmitted in the reverse direction. In theory, it has infinite isolation bandwidth, which is verified by simulation and an experiment. The other isolator is a differential transmission isolator (DTI) to improve the anti-interference performance, which consists of four Wilkinson power splitters (combiners) and two reciprocal transmission line segments. The DTI uses two pairs of differential signals to prevent the reverse signal. Compared to the STI, the DTI has higher power capacity. Furthermore, when the phases of the control signals acting on the switches are changed, the isolation directions of the two isolators will be changed, to obtain the reconfigurable property.