Pseudo-Linear Time-Invariant Magnetless Circulators Based on Differential Spatiotemporal Modulation of Resonant Junctions

Kord, Ahmed; Sounas, Dimitrios L.; Alù, Andrea

doi:10.1109/tmtt.2018.2818152

Cited by 69 publications

(44 citation statements)

References 32 publications

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“…In [22], circulating the fluid physically in a resonant ring cavity splits the ring's azimuthal resonant modes and produce significant acoustic nonreciprocity. In the electronic domain, STM has been used to achieve angular-momentum biasing and non-reciprocity [23]- [29]. For example, in [23], angular momentum-biased devices are presented in a ring structure with continuous capacitive loading.…”

mentioning

confidence: 99%

Isolating Bandpass Filters Using Time-Modulated Resonators

Liu

Hickle

et al. 2019

IEEE Trans. Microwave Theory Techn.

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In this paper, we demonstrate for the first time an isolating bandpass filter with low-loss forward transmission and high reverse isolation by modulating its constituent resonators. To understand the operating principle behind the device, we develop a spectral domain analysis method and show that same-frequency non-reciprocity is a result of non-reciprocal frequency conversion to the intermodulation (IM) frequencies by the time-varying resonators. With appropriate modulation frequency, modulation depth, and phase delay, the signal power at the IM frequencies is converted back to the RF frequency and add up constructively to form a low-loss forward passband, whereas they add up destructively in the reverse direction to create the isolation. To validate the theory, a lumped-element 3-pole 0.04-dB ripple isolating filter with a center frequency of 200 MHz, a ripple bandwidth of 30 MHz, is designed, simulated, and measured. When modulated with a sinusoidal frequency of 30 MHz, a modulation index of 0.25, and an incremental phase difference of 45 • , the filter achieves a forward insertion loss of 1.5 dB and a reverse isolation of 20 dB. The measured non-modulated and modulated results agree very well with the simulations. Such nonreciprocal filters may find applications in wide-band simultaneous transmit and receive radio front-ends.

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confidence: 99%

Isolating Bandpass Filters Using Time-Modulated Resonators

Liu

Hickle

et al. 2019

IEEE Trans. Microwave Theory Techn.

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“…Note that BW IX is smaller than transmission bandwidth BW 3dB . This is generally true in other STM-based circulator/isolator works [21]- [29], [35], [36]. The non-reciprocal bandwidth is bounded by the inherent static bandwidth and 2f m [28].…”

Section: MMmentioning

confidence: 82%

Frequency Tunable Non-Reciprocal Bandpass Filter and Diplexer Using Time-Modulated Microstrip λg/2 Resonators

Wu¹,

Nafe²,

Melcón³

et al. 2020

Preprint

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This paper presents novel designs of frequency reconfigurable distributed non-reciprocal bandpass filter and diplexer based on spatio-temporally modulated microstrip λg/2 resonators. The modulation is achieved by loading both ends of the λg/2 transmission line resonators with time-modulated capacitors. To provide an inherent biasing isolation between the RF and the modulation signals, the modulation voltage source is connected at the center of the resonator, where there is a natural voltage null. A single inductor is used to further enhance such biasing isolation. The wideband nature of this isolation scheme enables the tuning of the devices over a wide frequency range. With more than 30-dB RF to modulation isolation, the proposed resonator structure also enables low insertion loss by eliminating RF signal leakage to the modulation ports. Two examples of a 3-pole bandpass filter and a diplexer are demonstrated with good agreement between the measurement and the simulation. The fabricated filter shows a minimal insertion loss of 3.9 dB, a 20-dB isolation bandwidth of 42 MHz at 1.0 GHz, and frequency tuning range of 885-1031 MHz. The measured diplexer has two non-reciprocal bandpass channels at 829 MHz and 997 MHz, respectively. The two channels can be independently reconfigured without affecting each other.

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“…The insertion loss of the coupler at the center frequency is 4.8 dB, which is sufficiently close to the 3 dB insertion loss of an ideal lossless RR coupler. The 1.8 dB increase in the insertion loss is associated with the excitation of intermodulation products [41,56]. Impressively, the whole circuit is nearly inductorless and can be implemented on chip in a deeply subwavelength footprint [40].…”

Section: A Miniaturized Rat-race Couplermentioning

confidence: 99%

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

et al. 2019

Self Cite

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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.

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Pseudo-Linear Time-Invariant Magnetless Circulators Based on Differential Spatiotemporal Modulation of Resonant Junctions

Cited by 69 publications

References 32 publications

Isolating Bandpass Filters Using Time-Modulated Resonators

Isolating Bandpass Filters Using Time-Modulated Resonators

Frequency Tunable Non-Reciprocal Bandpass Filter and Diplexer Using Time-Modulated Microstrip λg/2 Resonators

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

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