Frequency Independent Framework for Synthesis of Programmable Non-reciprocal Networks

TL;DR

This paper introduces a frequency-independent framework for synthesizing multi-port nonreciprocal microwave networks, enabling broadband, programmable, and scalable nonreciprocal devices for advanced wireless communication systems.

Contribution

The authors present a novel, highly expandable framework for designing frequency-independent nonreciprocal networks with arbitrary ports and high programmability, demonstrated by a broadband 4-port circulator.

Findings

Achieved broadband nonreciprocal performance from 10 MHz to 900 MHz.

Demonstrated high programmability with temporal switching at 23.8 MHz.

Framework is scalable to multiple ports with balanced performance.

Abstract

Passive and linear nonreciprocal networks at microwave frequencies hold great promises in enabling new front-end architectures for wireless communication systems. Their nonreciprocity has been achieved by disrupting the time-reversal symmetry using various forms of biasing schemes, but only over a limited frequency range. Here we demonstrate a framework for synthesizing theoretically frequency-independent multi-port nonreciprocal networks. The framework is highly expandable, and can have an arbitrary number of ports while simultaneously sustaining balanced performance and providing unprecedented programmability of non-reciprocity. A 4-port circulator based on such a framework is implemented and tested to produce broadband nonreciprocal performance from 10 MHz to 900 MHz with a temporal switching effort at 23.8 MHz. With the combination of broad bandwidth, low temporal effort, and high programmability, the framework could inspire new ways of implementing multiple input multiple output (MIMO) communication systems for 5G.