Role of Synchronization in Magnetless Nonreciprocal Devices Based on Commutated Transmission Lines

Commutated transmission lines have been recently explored as an interesting way to break Lorentz reciprocity, avoiding any resonant structure, and enabling broad bandwidths with giant isolation combined with lenient requirements on the modulation frequency. The scheme relies on precise synchronization among different switches connected through transmission lines, offering in principle infinite bandwidth. Here, we investigate the effects of realistic switching parameters and synchronization on the device performance, providing interesting physical insights on the operation of these devices. Our research shows that the nonreciprocal response of these systems experiences a linear regression of insertion loss and isolation with respect to the timing error among switches. Remarkably, impedance matching and nonreciprocal phase shifts are immune from synchronization issues, and reasonable levels of synchronization errors still guarantee low insertion loss and good isolation. Our study also provides practical guidelines to envision nonreciprocal devices based on commutated modulation of conductivity, opening interesting opportunities for several fields of technology, including wireless communications, quantum technologies, and photonic circuits.