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Reduced order derivation of the two-dimensional band structure of a mixed-mode resonator array
摘要： In this paper, the 2D band structure of a mixed-mode metamaterial resonator array for in-plane waves is investigated. The band structure in the interior and on the boundary of the irreducible Brillouin zone and 1D dispersion diagrams for different propagation angles are calculated numerically and presented. Additionally, a reduced order analytical method is established to compare and approximate the band structure. The studied metamaterial, with a T-shaped cantilever beam as the resonator in its square array repeating unit cells, exhibits branches with mixed P and SV waves except at exactly one angle of propagation. This paper also reports on the occurrence of avoided level crossings, which are related to the existence of exceptional points in the complex domain. A reduced order analytical approach is used that can generate partial (low branches) band structure with relatively little computational effort. The reduced order model agrees well with the numerical results for these low branches and can provide support in mode identification and band sorting. With proper adjustments in parameters, this analytical method will be applicable to other metamaterials that have a similar unit cell structure.
关键词： band structure,reduced order model,resonator array,metamaterial,avoided level crossings,mixed-mode waves
更新于2025-09-23 15:23:52
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Single-Layer Dual-Band Balanced Substrate- Integrated Waveguide Filtering Power Divider for 5G Millimeter-Wave Applications
摘要： A single-layer substrate-integrated waveguide (SIW) filtering power divider (FPD) with fully differential operation at 28 and 39 GHz is proposed in this letter. This FPD consists of three SIW cavities where the differential and common modes of each cavity were properly designed to form three-pole dual passbands, facilitate deployment of isolation resistors, and introduce transmission zeros while attaining high in-band common-mode rejection. To improve the output return loss and isolation in dual bands, a novel and simple approach to find the proper location of isolation resistors is presented. At operating frequencies, the measured differential-mode input or output return loss, minimum insertion loss, isolation, and common-mode suppression are >14.1 dB, <(3 + 2.2) dB, >14.9 dB, and >30.3 dB, respectively. The amplitude and phase imbalances between outputs are <0.48 dB and <4.2?, respectively.
关键词： balanced,dual-band,isolation resistor,common-mode rejection,substrate-integrated waveguide (SIW),differential,single-layer,mixed-mode,filtering power divider (FPD),5G
更新于2025-09-23 15:21:01
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A Balanced-to-Single-Ended Wilkinson Power Divider
摘要： A balanced-to-single-ended (BTSE) Wilkinson power divider of planar microstrip structure is proposed in this paper. It has a balanced input and two single-ended outputs. Cascade of a balun and a conventional power divider can be replaced by this proposed structure. Based on the theory of mixed-mode S parameters and the admittance matrix method, the critical parameters are determined. The four-port network is analyzed by simplifying it to two-port network with other ports matched at the central frequency. Then the key parameters are derived and the impact of a freely selected variable on the bandwidth is also discussed. An example of 2.4GHz BTSE power divider is designed. The simulated and measured results show the effectiveness of the method: differential-mode transmissions are better than -3.25dB, common-mode transmissions are lower than -28.6dB, common- mode return loss is -0.10dB, differential-mode return loss and isolation is lower than -23.7dB. While the operating bandwidth is 20%.
关键词： mixed-mode S-matrix,balanced circuit,power divider
更新于2025-09-23 15:21:01
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Rare events in mixed-mode oscillations from weakly coupled lasers
摘要： We study a dynamical system consisting of two mutually coupled molecular lasers, each of which shows mixed-mode oscillations and chaos when uncoupled. The type of coupling, incoherent laser interaction via saturable absorbers is an example of inhibitory nonlinear coupling, which is also found in Hodgkin-Huxley models that describe action potentials in neurons. We have carried out extensive numerical bifurcation analysis and numerical simulations to show that for small-enough coupling, well below the chaotic synchronization threshold, the presence of distinctive resonances in a symmetric mirror con?guration of the system generates a type of rare events characterized by very small amplitudes. When this symmetry is broken by introducing a relatively small difference between the lasers pump parameters near an in-phase Hopf bifurcation, we observe extreme rare events (rogue waves) in one of the lasers. In this case the outliers deviate from power-law distributions and are reminiscent of those known as dragon kings. We consider the conditions for both types of rare events to occur, their origin, as well as relevant statistical features.
关键词： mixed-mode oscillations,dragon kings,rogue waves,weakly coupled lasers,rare events
更新于2025-09-12 10:27:22
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - On-Wafer CPW Standards for S-Parameter Measurements of Balanced Circuits Up to 40 GHz
摘要： The Multimode Thru-Reflect-Line (TRL) calibration technique is applied to perform mixed-mode scattering parameter measurements of on-wafer differential circuits. The paper describes the design and the realization of coupled coplanar waveguide (CCPW) standards on quartz (SiO2) substrate in the Ground-Signal-Ground-Signal-Ground (GSGSG) configuration. Simulation and measurement results for a mismatched transmission line demonstrate the validity of the method up to 40 GHz.
关键词： Coplanar waveguide,Multimode TRL calibration,vector network analyzer,mixed-mode Scattering parameters,differential circuits,microwave measurements
更新于2025-09-10 09:29:36
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Engineering Interface-Dependent Photoconductivity in Ge <sub/>2</sub> Sb <sub/>2</sub> Te <sub/>5</sub> Nanoscale Devices
摘要： Phase change materials are increasingly being explored for photonics applications, ranging from high resolution displays to artificial retinas. Surprisingly, our understanding of the underlying mechanism of light-matter interaction in these materials has been limited to photothermal crystallization, because of its relevance in applications such as re-writable optical discs. Here we report a photoconductivity study of nanoscale thin films of phase change materials. We identify strong photoconductive behaviour in phase change materials, which we show to be a complex interplay of three independent mechanisms: photoconductive, photo induced-crystallization and photo-induced-thermoelectric effects. We find these effects also congruously contribute to a substantial photovoltaic effect, even in notionally symmetric devices. Notably, we show that device engineering plays a decisive role in determining the dominant mechanism; the contribution of the photothermal effects to the extractable photocurrent can be reduced to < 0.4 % by varying the electrodes and device geometry. We then show that the contribution of these individual effects to the photoresponse is phase-dependent with the amorphous state being more photoactive than the crystalline state and that a reversible change occurs in the charge transport from thermionic to tunnelling during phase transformation. Finally we demonstrate photodetectors with an order of magnitude tuneability in photodetection responsivity and bandwidth using these materials. Our results provide insight to the photo-physics of phase change materials and highlight their potential in future opto-electronics.
关键词： Mixed-Mode Operation,Photothermal effects,Tuneable Photodetector,Phase Change Materials,Photoconductivity
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE BiCMOS and Compound Semiconductor Integrated Circuits and Technology Symposium (BCICTS) - San Diego, CA, USA (2018.10.15-2018.10.17)] 2018 IEEE BiCMOS and Compound Semiconductor Integrated Circuits and Technology Symposium (BCICTS) - Revisiting Safe Operating Area: SiGe HBT Aging Models for Reliability-Aware Circuit Design
摘要： This paper presents and validates a physics-based compact aging model for predictive simulation of hot-carrier degradation in SiGe HBTs. Separate aging functions model the effects of high-field mixed-mode and high-current Auger-hot-carrier stresses and are integrated together to provide predictive capability across a wide bias range. The variation of aging rate with device geometry and the incorporation of multiple parameter shifts due to hot carrier polysilicon degradation are explored. Additionally, aging simulation results of a driver circuit are presented to begin to demonstrate how such models may be incorporated as part of the circuit design process.
关键词： SiGe HBT,safe operating area,mixed-mode stress,high-current stress,reliability
更新于2025-09-04 15:30:14