This paper provides a comprehensive study of signal integrity issues in RRAM-based neuromorphic chip crossbar arrays due to interconnect parasitic. First, the parasitic parameters of the crossbar ...array are calculated by the partial equivalent element circuit (PEEC) method with an efficient unit-cell approach. Numerical experiments show that for a <inline-formula> <tex-math notation="LaTeX">50\times 50 </tex-math></inline-formula> array scale, this method consumes only 1.5% of the calculation time of the commercial software based 3D model, which translates to a calculation speed up of 72 times. Moreover, the PEEC circuit simulation results match well with those of the 3D model. Then, we investigate the effects of parasitic parameters such as capacitance and inductance, as well as the feature size of the crossbar array on signal integrity. All of them will lead to corresponding changes in parasitic effects, which in turn result in the most common signal integrity issues such as crosstalk, time delay and mutual capacitive coupling induced sneak path problem. Different from other studies, the excitation used in this paper is the neural spike signal generated by the Izhikevich neuron model, which is both rich in dynamic characteristics and high in computational efficiency. Finally, based on the study we propose a simple but effective design scheme for reduction of signal distortion, which can provide valuable design guidance for neuromorphic systems to achieve high performance and high computational accuracy.
This article presents a novel and efficient near-field scanning method for coupling path visualization of conductive electromagnetic interference (EMI) using sparse scanning samples based on active ...machine learning. A high-voltage discharge system with a false triggering problem is studied as the device under test (DUT). Near-field scanning is adopted to measure the time-domain waveform of the conductive current and investigate the coupling path of the conductive EMI that causes the false triggering issue. To facilitate the time-consuming near-field scanning process, an adaptive sampling approach based on active learning is proposed to seek the most informative locations and minimize the number of scanning samples. Through the developed active learning method, the scanning process is more efficient and intelligent than random sampling and a uniform-like sampling strategy called greedy sampling. Moreover, the dominant EMI coupling path in a key area is clearly visualized. By cutting off the identified coupling path, the false triggering phenomenon is effectively eliminated. The proposed active learning method is much more efficient than the conventional full scanning, and can be applied to expedite various near-field scanning scenarios.
This letter proposes an iteration-free-phase retrieval method for directive radiators based on field amplitudes on two closely separated observation planes. Due to the small separation, local ...optimization suffers from converging to local minima, and global optimization consumes long CPU time. In the proposed method, the Huygens' principle and the image theory are applied on the first observation plane, and the complex-valued field quantities on the two observation planes are related through the radiation matrix. The radiation matrix is then scaled by the field amplitudes on the two observation planes. It is shown that, if the phase difference between the two observation planes is relatively uniform, an eigenvector of the scaled radiation matrix constitutes a solution to the phase retrieval problem, which achieves iteration-free-phase retrieval. The problem of convergence to local minima is thus avoided. Simulation results are presented to show the effectiveness of the proposed method.
Recent breakthroughs in deep learning have ushered in an essential tool for optics and photonics, recurring in various applications of material design, system optimization, and automation control. ...Deep learning-enabled on-demand metasurface design has been the subject of extensive expansion, as it can alleviate the time-consuming, low-efficiency, and experience-orientated shortcomings in conventional numerical simulations and physics-based methods. However, collecting samples and training neural networks are fundamentally confined to predefined individual metamaterials and tend to fail for large problem sizes. Inspired by object-oriented C++ programming, we propose a knowledge-inherited paradigm for multi-object and shape-unbound metasurface inverse design. Each inherited neural network carries knowledge from the "parent" metasurface and then is freely assembled to construct the "offspring" metasurface; such a process is as simple as building a container-type house. We benchmark the paradigm by the free design of aperiodic and periodic metasurfaces, with accuracies that reach 86.7%. Furthermore, we present an intelligent origami metasurface to facilitate compatible and lightweight satellite communication facilities. Our work opens up a new avenue for automatic metasurface design and leverages the assemblability to broaden the adaptability of intelligent metadevices.
The flexibility of an antenna structure can influence its S-parameters by affecting resonance frequency. Stability in resonance frequency is essential for flexible applications to ensure consistent ...and reliable antenna performance across varying conditions. In this article, we present the concept of resonance tolerance for different bending cases utilizing the toroidal dipole metasurface. The flexibility of the polyimide substrate allows for a minor 1.043% shift in the resonance when the planar metasurface of the toroidal dipole is curved at a 4.53-radian angle, and applying a stretching of approximately 0.12% to the structure leads to a decrease of 2.01% in the resonant frequency. Furthermore, when the flexible toroidal metastructure is positioned in proximity (5mm-10mm) to a human arm phantom, the consistently favorable reflection coefficients demonstrate that the flexible toroidal metastructure operates effectively within the frequency range of 3.55-3.8399 GHz. This highlights the potential of our proposed flexible toroidal dipole antenna for wearable, flexible electronic devices, with a particular emphasis on its application within the ISM band.
Conventional package lid induces additional unintentional radiation due to the resonances between the conventional metal lid and ground plane on package board. In this paper, a novel package lid is ...proposed based on the gap waveguide theory, which adopts mushroom-type electromagnetic bandgap structures to mitigate the increased unintentional emission. In addition, a scalable equivalent circuit model is presented as an assistance for designing the proposed package lid. Both the simulation and measurement results confirm that the proposed lid can significantly reduce the unintentional radiation within the specific frequency range as designed.
This article focuses on realizing wideband compartment shielding in the shielding can packages of miniaturized high-speed chip modules and circuits. Because the conventional diaphragms with a low ...profile are difficult to cope with the high-order mode interference and evanescent wave interference, a new "meta-diaphragm," which is based on the single-negative (SNG) metamaterial, is proposed to address these inherent problems. It is demonstrated that benefitting from the large propagation attenuation introduced by the proposed meta-diaphragm, a good shielding performance can be achieved at the first higher order resonance mode. Moreover, by elaborately embedding resistors in the meta-diaphragm, the additional interferences at other resonance frequencies can be significantly suppressed. Furthermore, the structure of the meta-diaphragm is optimized with two approaches: evolving from the single-band SNG structure to the double-band one and integrating with the parasitic patches. The two approaches enable its independent controlling ability at different frequency ranges and enhancement of low-frequency shielding performance. Based on the proposed technique, an experiment is implemented to suppress the resonance-dominated interference between the passive traces in a shielding can. The result agrees well with those from theoretical prediction. The final experimental shielding can's profile and width are 5 and 20 mm, respectively; the meta-diaphragm's profile is only 1.5 mm, i.e., < 1/3 of shielding can's profile, and its electrically length is only 3 mm, i.e., <inline-formula> <tex-math notation="LaTeX">0.1\lambda _{0} </tex-math></inline-formula> at 10 GHz, and the measured (simulated) meta-diaphragm can significantly suppress radio frequency interference (RFI) within 10.2-17 GHz (10-16.9 GHz) and realize <inline-formula> <tex-math notation="LaTeX">< -33.5 </tex-math></inline-formula> dB (<inline-formula> <tex-math notation="LaTeX">< -40 </tex-math></inline-formula> dB) coupling within 100 kHz-18 GHz (dc-to-20 GHz). The miniaturized dimension and wideband results indicate that our proposed technique could meet the compartment shielding requirement of a series of miniaturized packages in the practical radio frequency (RF) chip modules and circuits.
The investigation of few-layer graphene embedded in silicon waveguide (GESW) exhibits it has a superior performance than monolayer GESW where the effective mode index variation (Δneff) at the given ...chemical potential change and the number of graphene layers N (N<5) shows in a linear relationship. The results from modal analysis show that the Δneff of quadri-layer GESW can be as large as 0.047, based on which a Mach–Zehnder modulator has been proposed with the advantages of only 16.5μm arm length, low energy consumption (8fJ/bit), high extinction ration (31.8dB) and small applied voltage (<1V). Furthermore, the working temperature of the proposed modulator can span in a large range from 300K to 400K and the modulation performance stays almost unchanged when the input wavelength varies from 1520nm to 1580nm.
This article proposes several low-profile metasurface-based compartment shielding diaphragms for the high-speed and highly integrated circuits located in the space-limited cavities. It was ...demonstrated that the capacitive metasurface (CMS) and inductive metasurface (IMS) partially filled in the cross section of cavities can generate new transverse electric and magnetic resonance modes, which are orthogonal to the TE 10 mode of the cavity. Benefitting from the mode-mismatch between the transverse electric/magnetic resonance modes and the TE 10 mode, a large shielding effectiveness (SE) can be obtained. It is found that, even when the metasurfaces are designed with a low profile (the ratio between the metasurfaces' profile and the cavity's height <inline-formula> <tex-math notation="LaTeX">h/h_{c} < 0.5 </tex-math></inline-formula>), they can introduce a large SE at a desired frequency band, which is deemed difficult to achieve by utilizing conventional waveguide diaphragms with such a profile. Moreover, the CMS and IMS can be aligned as a complementary metasurface (CPMS) to enhance the working bandwidth significantly, by elaborately designing their surface impedances. The CMS, IMS, and CPMS samples with a thickness less than <inline-formula> <tex-math notation="LaTeX">0.1\lambda _{0} </tex-math></inline-formula> and a profile less than <inline-formula> <tex-math notation="LaTeX">0.15\lambda _{0} </tex-math></inline-formula>, i.e., less than one-third of the cavity's height, were fabricated and tested in a compartment scenario, respectively. The developed technique is validated by the good agreement between the simulation and measurement results. The low-profile shielding diaphragms reported in this work can provide the effective solutions in many compartment shielding scenarios, such as integrated radio frequency (RF) modules and system-on-chip (SoC) packages.
