On-chip non-reciprocal components based on angular-momentum biasing

Ferromagnetic media have dominated the nonreciprocal device industry for a long time, but cost, weight, and integration limitations have led researchers in recent years to seek alternative solutions. Among the different magnet-less concepts proposed to date to realize on-chip non-reciprocity, the idea of using angular momentum to replace the magnetic bias has been shown to provide unprecedented levels of isolation and nonreciprocal response, with advantages in terms of tunability, linearity and low-noise response. Here, we present the recent advances on this class of microwave components, and propose a lumped-element circulator with optimized performance based on this concept. Furthermore, we study the linear properties of the component, and propose approaches for improving them.