This letter presents a novel graphene-embedded optical ring modulator that significantly enhances the modulation efficiency and tunability. Due to the enhanced light-matter interaction of ...graphene-embedded design, the shift rate of the resonance peak has been improved to 1.08 nm per applied voltage, which is two orders of the magnitude higher than previous ring modulators. The narrow bandwidth of the resonant modulator has been ameliorated to 149 GHz. In addition, our proposed modulator exhibits the advantages of high extinction ratio (22.13 dB) and smaller power consumption. Furthermore, a good tolerance of temperature drift (27 K) has been demonstrated in the proposed modulator.
Placing ground vias plays a crucial role in mitigating electromagnetic radiation from printed circuit board (PCB) edges. Stitching dense ground vias along PCB edges is not always feasible due to ...limited layout areas. Finding a ground-via placement strategy to achieve the best electromagnetic interference (EMI) mitigation using a specified number of ground vias is desired in the industry. However, this process is usually tedious and labor-intensive because of the enormous search space. This article proposes an optimization algorithm based on deep reinforcement learning to adaptively seek the optimal ground-via placement strategy in complex packages. First, an evaluation module based on convolutional neural networks (CNNs) is trained to predict the EMI mitigation for any possible ground-via placement. Then, relying on the well-trained CNN, an optimization module based on dueling double deep Q network is developed to find the best ground-via placement strategy through exploration and training without prior electromagnetic knowledge. The final optimization strategy obtained by our proposed algorithm has more effective EMI mitigation than the commonly used "edge-wrapping" solution in industrial products. Our proposed algorithm also provides guidelines and insights about the design rule and the behind physics.
As the radiation leakage from solder balls of system-in-package becomes increasingly significant, this article presented a novel analysis and design method for pin map distribution scenarios by ...combining electromagnetic theory and machine learning technology. First, an empirical virtual boundary generalized T-matrix (VBGT) method is proposed in this article to analyze the pin map structure with finite dimensions and imperfect boundaries, enabling rapid computation of edge-field and far-field radiation. Subsequently, an enhanced deep Q-network that couples the VBGT method and deep reinforcement learning is developed to optimize the pin allocation. Finally, the results from various real-world pin map cases demonstrate the efficiency and reliability of the proposed VBGT-DRL algorithm, which holds promising application potential in the automatic pin assignment design of system-in-package for electromagnetic interference self-shielding.
System-in-Package (SiP) has been facing the problem of excessive radiation leakage. In this article, a novel technique of absorptive sheet is proposed for suppressing unwanted microwave radiated ...emission in an advanced high-speed SiP module backed with a heat sink. Different from the conventional periodic resonant structure or absorptive film, the electromagnetic energy is consumed based on the mechanism of spoof surface plasmon polaritons (SSPP) in our design. By adjusting the length of the metallic strip to control its k-dispersion characteristics, the SSPP modes could be excited around one frequency point. Therefore, a relatively wide absorption band is created by arranging stepped strips in arrays on a dielectric medium. According to the electromagnetic distribution in the SiP module, SSPP-based absorptive units are circularly arranged to constitute the complete proposed absorptive sheet with adequate absorption efficiency. From the simulated results, the proposed design can provide 90<inline-formula><tex-math notation="LaTeX">\%</tex-math></inline-formula> absorption performance covering a wide frequency range of 26.3-31.6 GHz, with a substrate thickness of only <inline-formula><tex-math notation="LaTeX">\lambda _{L}</tex-math></inline-formula>/228 and a total thickness of <inline-formula><tex-math notation="LaTeX">\lambda _{L}</tex-math></inline-formula>/134, where <inline-formula><tex-math notation="LaTeX">\lambda _{L}</tex-math></inline-formula> is the wavelength at the lowest operating frequency. Finally, the proposed absorptive sheet is fabricated and measured, where measurement results agree well with the simulated ones, which corroborates the feasibility and effectiveness of applying the SSPP-based absorbing techniques for suppressing the radiated emission in microwave and millimeter-wave frequency range in SiP modules.
Four new gallate derivatives-ornusgallate A,
-cornusgallate A, cornusgallate B and C (1a, 1b, 2, 3)-were isolated from the wine-processed fruit of
. Among them, 1a and 1b are new natural compounds ...with novel skeletons. Their chemical structures were elucidated by comprehensive spectroscopy methods including NMR, IR, HRESIMS, UV, ECD spectra and single-crystal X-ray diffraction analysis. The in vitro anti-inflammatory activities of all compounds were assayed in RAW 264.7 cells by assessing LPS-induced NO production. As the result, all compounds exhibited anti-inflammatory activities at attested concentrations. Among the tested compounds, compound 2 exhibited the strongest anti- inflammatory activity.
A metamaterial unit cell with a low refractive index over a wide frequency band is proposed and designed. The effective material parameters of the unit cell are extracted, and the unit cell forms a ...planar three-layer metamaterial structure used as a superstrate for broadside gain enhancement of a patch antenna at 10 GHz. The proposed superstrate is optimized along with the antenna to enhance its beam-focusing ability, taking into account the oblique wave incidence from the radiation source. Both simulation and measurement of the antenna with the optimized superstrate show that this configuration is able to achieve a broadside gain 70%-80% of the maximum gain from the ideal effective radiation surface.
Heat sink is widely mounted on the integrated circuits to optimize thermal performance. Unfortunately, the cavity resonance between heat sink and package substrate could lead to severe radiation ...problem, causing that the product fail to satisfy the relevant electromagnetic interference (EMI) standards. It is a critical challenge to simultaneously obtain the excellent radiation attenuation and desirable thermal performance. In order to solve the problem, a combination of ring-shaped absorbing material and flat-shaped graphite is proposed in this paper. Based on a typical wire-bonded package, the effect of graphite on mitigating radiation and optimizing the thermal performance is investigated. As the graphite size varies from 20 to 45 mm, temperature reduction 5 °C and radiation attenuation 10 dB absorption bandwidth is realized. The experiment for EMI radiation is conducted in a semianechoic chamber, and the results of simulation and experiment matched well.
A vertically polarized (VP), electromagnetic interference (EMI) suppressed millimeter-wave (mm-W) active heatsink antenna based on the gap waveguide technology is presented, which combines a compact ...passive heatsink antenna and an mm-W power amplifier (PA) circuit. The passive heatsink antenna consists of the groove-gap waveguide (GGW) and the feeding structure, which can enable the VP radiation, introduce two adjustable out-of-band filtering nulls, and enhance the in-band interference suppression level. Meanwhile, the feeding structure is compatible with the PA circuit layout, and the GGW-structure well improves the heat dissipation performance, which achieves an excellent fusion between the antenna and the PA circuit. A prototype was fabricated, assembled, and tested. The measurement results demonstrate that the proposed active heatsink antenna can achieve a VP radiation with the peak effective gain of 18.17 dBi in the 3-dB passband 23.45-26.58 GHz. Besides, the active heatsink antenna exhibits good EMI suppression performance, including >16.71-dB out-of-band filtering in the effective gain curve and >17.25-dB in-band shielding between the antenna and the adjacent circuits. Moreover, the thermal performance of the heatsink is enhanced and it guarantees that the PA circuit works in a stable state. The proposed design is a good candidate for mm-W applications in complex electromagnetic (EM) environments, such as vehicle radar.
This paper presents the efficient systematic methods for modeling and analysis of spike signal sequence in crossbar arrays for neuromorphic computing chips. A novel spike signal sequence is proposed, ...where the ideal spike sequence with only spike time information in the original spiking neural network (SNN) algorithm is mapped onto actual spike waveform by stitching neighboring sequential spikes together with certain overlaps. We thoroughly investigate and analyze the performance of the input encoding as well as the implementation of spike timing dependent plasticity (STDP)-based SNN on memristor crossbar arrays with the proposed spike signal sequence. A detailed circuit model of a crossbar array, consisting of resistance, capacitance and inductance derived by the partial equivalent element circuit (PEEC) method, is created to simulate the training process of SNN. The proposed spike signal sequence is demonstrated that is able to achieve accurate input encoding as well as high recognition accuracy when it is used to perform the classification task on MNIST handwritten digits. The spike signal sequence is further analyzed and assessed in terms of the main factors affecting its encoding accuracy and the parasitic effects of crossbar arrays on its robustness.
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