A Millimeter-Wave Non-Magnetic Passive SOI CMOS Circulator Based on Spatio-Temporal Conductivity Modulation

Quasielectrostatic Wave Propagation Beyond the Delay-Bandwidth Limit in Switched Networks

“…In principle, it is also possible to configure any of the three sections to act as a gyrator; however, the scattering parameters are already nearly symmetrical. At the center frequency, the circulator exhibits the insertion loss of around 2.5 dB, on par with other magnetless circulator topologies [38][39][40][41][42][43][44], while being electrically a much smaller device. Similar to the rat-race coupler, the circulator bandwidth is limited only by different slopes of the phase profiles of reciprocal sections and the gyrator, and, therefore, the center frequency can be dynamically tuned by changing f s .…”

“…The fact that commutated networks provide nonreciprocal phase shifts has been successfully employed to realize a variety of magnetless nonreciprocal devices, such as circulators, gyrators, and isolators [40][41][42][43][44]. All these designs, however, rely on transmission-line sections or LC tanks operating as delay lines to obtain required reciprocal phase shifts.…”

“…Inspired by all these interesting developments, in this paper, we show that synchronized spatial and temporal periodic modulation may be used to fundamentally overcome the delay-bandwidth limit of time-invariant systems by breaking the dependence of phase and group velocities on the properties of the constituent elements. Over the past few years, spatiotemporal modulation has gained significant attention, in particular, due to the possibility of realizing miniaturized nonreciprocal components enabling the realization of magnet-free isolators [31][32][33][34], phase shifters [35], miniaturized radio frequency gyrators, and circulators [36][37][38][39][40][41][42][43][44]-important breakthroughs on the way towards integrated communication systems. However, all these nonreciprocal devices, as well as many reciprocal ones, rely on large delays that provide the necessary phase shifts among their constituent subunits, fundamentally limiting their further miniaturization.…”

Integrated Conductivity-Modulation-Based RF Magnetic-Free Nonreciprocal Components: Recent Results and Benchmarking

“…Inspired by the N-path-filter-based RF circulator discussed in the previous subsection, we proposed a generalized conductivity modulation concept using switched transmission lines [32], [33]. The concept, shown in Fig.…”

“…In this letter, we will cover our recent research on using commutated circuits to break reciprocity and build high- [30], [31]. (b) Millimeter-wave switched-transmission-line circulator [32], [33]. (c) RF switched-transmission-line circulator with >1W powerhandling capability and inductor-free antenna balancing [34].…”