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

Abstract

The delay-bandwidth limit implies a stringent trade-off between the time delay, bandwidth, and propagation distance of an electromagnetic signal. Here, we show that temporal modulation can overcome this constraint, enabling extremely broadband wave propagation with close-to-zero group velocity dispersion in switched multipath electronic networks. Contrary to time-invariant waveguides, in which wave propagation implies a delicate balance between electric and magnetic stored energies, in such modulated networks the stored energy is largely electrostatic in nature. We show that in this case the phase and group velocities become independent of the properties of their constituent elements, and they are controlled only by the modulation scheme. Based on these findings, we provide practical designs of deeply subwavelength CMOS-compatible reciprocal and nonreciprocal microwave components, such as delay lines, phase shifters, couplers, and circulators. The obtained results also explicitly show that temporally modulated systems are not bound by constraints of time-invariant systems and can achieve arbitrarily large delay-bandwidth products.

Time-modulated Patch Antennas with Tunable and Nonreciprocal Polarization Ellipticity

“…It should be noted that the main goal of this paper was to demonstrate nonreciprocal polarization control, and thus the devices were not fully optimized for other applications. Future antennas will benefit from available techniques based on timemodulation [48,49] or switched networks [50,51] to enhance their operational bandwidth and reduce loss while keeping their nonreciprocal nature. Additionally, the proposed concept can be extended to account for any polarization state of the Poincaré sphere.…”

A Clock-Phase Reuse Technique for Discrete-Time Bandpass Filters

“…A key advantage of this structure, however, is that the I /Q CS BPF does not suffer from replicas and can provide robust filtering covering the entire range − f s /2 to f s /2 [19], especially when lower center frequencies are targeted (e.g., few tenths of megahertz). It is worth mentioning that the N-path filter also has no replicas in the entire range − f s /2 to f s /2 from its center frequency f c even up to f max < N f s /2 [20]. However, as stressed in [1], there is a direct relationship between the sampling and center frequencies in the N-path filter ( f c = f s ).…”

Non-Magnetic Non-Reciprocal Microwave Components — State of the Art and Future Directions

“…While these implementations have paved the way towards integrated non-reciprocal components with performance metrics that are beginning to be relevant for practical applications [76], the use of conventional reciprocal elements such as transmission lines and couplers within these non-reciprocal structures still imposes limits on size, bandwidth and insertion loss. In a different context, N-path, commutated, switched-capacitor networks have been shown to exhibit extremely-broadband slow-wave propagation beyond the conventional delay-bandwidth limit, enabling the realization of a low-loss, ultra-broadband, reconfigurable, reciprocal/non-reciprocal delay element [77]. Due to the usage of just switches and capacitors, such a delay element can be implemented in an extremely-compact form factor.…”