Magnetic-free non-reciprocal and topological integrated microwave components based on tunable filter networks​

This proposal will explore the design and fabrication of tunable nonreciprocal devices for isolation, full-duplex operation, and incorporation in topological insulators. The topologies will be based on time-modulated Wheatstone bridges of varactors connected through filters. We will explore using dual-mode filters that provide independent control over the common and differential modes of the circuit for better alignment of the scattering parameters. We will investigate circuits with multiple stage filters for reducing loss and the modulation amplitude, while keeping the modulation frequency low. Furthermore, we will target making the proposed circuits tunable by adding varactors in the filters. The proof-of-concept circuit will be a non-reciprocal circulator operating in the S-band with isolation better than 20 dB, insertion loss less than 2 dB, and tuning at least 10% of the center frequency. Later in the program, non-reciprocal integrated circuits will be designed for operating at higher frequencies, such as 5G.