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Auditory system in animals can capture external sound signals, which can be converted into biophysical electric signals, and then the auditory neurons are activated to generate kinds of firing patterns. Bats can detect signals with ultrahigh frequency while human auditory system is sensitive to sound and voice within the frequency range 20 to 20,000 Hertz. In this paper, a piezoelectric neuron is proposed to investigate the physical mechanism for selection of frequency and filtering in auditory wave, and filtering wave function is designed to simulate the mode selection in the electrical activities of auditory neuron. Sound signals with multiple frequencies are imposed to drive the auditory neuron and mode selection is analyzed in detail. A decay factor is introduced to control the wave filter and frequency selection, and the amplitude is decreased sharply within transient period when the frequency is beyond or below the threshold. Furthermore, additive noise is accompanied by the sound signals and the mode selection is investigated by taming the noise intensity carefully. It is found that intermediate noise intensity can enhance nonlinear resonance and the auditory wave is encoded to induce regularity in the neural activities. The results can be helpful for further designing smart sensor and wave filter in signal processing, and the biophysical mechanism for signal processing in auditory system is clarified.

This paper presents a comprehensive review of advancements in wafer-level packaging (WLP) technology, with a particular focus on its application in surface acoustic wave (SAW) and bulk acoustic wave (BAW) filters. As wireless communication systems continue to evolve, there is an increasing demand for higher performance and miniaturization, which has made acoustic wave devices—especially SAW and BAW filters—crucial components in the Radio Frequency (RF) front-end systems of mobile devices. This review explores key developments in WLP technology, emphasizing novel materials, innovative structures, and advanced modeling techniques that have enabled the miniaturization and enhanced functionality of these filters. Additionally, the paper discusses the role of WLP in addressing challenges related to size reduction and integration, facilitating the creation of multi-functional devices with low manufacturing costs and high precision. Finally, it highlights the opportunities and future directions of WLP technology in the context of next-generation wireless communication standards.

Surface Acoustic Wave Filters gives the fundamental principles and device design techniques for surface acoustic wave filters.It covers the devices in widespread use today: bandpass and pulse compression filters, correlators and non-linear convolvers and resonators.

This study aims to enhance and tune wave-propagation properties (Bandgaps) of periodic structures featuring magnetorheological elastomers (MREs). For this purpose, first, a basic model of periodic structures (square unit cell with cross-shaped arms), which does not possess noise filtering properties in the conventional configuration, is considered. A passive attenuation zone is then proposed by adding a cylindrical core mass to the center of the conventional geometry and changing arm angles, which permitted new bandgap areas. It was shown that better wave-filtering performance may be achieved by introducing a large radius of the cylindrical core as well as low negative cross-arm angles. The modified configuration of the unit cell was subsequently utilized as the basic model for the development of magnetoactive metamaterial using a MRE capable of varying the bandgaps areas upon application of an external magnetic field. The finite element model of the proposed MRE-based periodic unit cell was developed, and the Bloch theorem was employed to systematically investigate the ability of the proposed adaptive periotic structure to attenuate low-frequency noise and vibration. Results show that the proposed MRE-based periodic wave filter can provide wide bandgap areas which can be adaptively changed and tuned using the applied magnetic field. The findings in this study can provide an essential guide for the development of novel adaptive periodic structures to filter low-frequency noises in the wide frequency band.

The development of mobile 5G technology poses new challenges for high-frequency and high-performance filters. However, current commercial acoustic wave filters mainly focus on 4G LTE, which operates below 3 GHz. It is necessary to accelerate research on high-frequency acoustic wave filters. A high-selectivity film bulk acoustic resonator (FBAR) filter chip for the 3.4–3.6 GHz range was designed and fabricated in this paper. The design procedure includes FBAR parameter fitting, filter schematic analysis, and the generation principle of transmission zeros (TZs). The measured results show that the filter chip is of high roll-off and stopband suppression. Most of the stopband suppression is better than 35 dB. Finally, error analysis was conducted, and FBAR parameters were modified after testing for future filter design work.

Electromagnetic components greatly contribute to the peculiar timbre of analog audio gear. Indeed, distortion effects due to the nonlinear behavior of magnetic materials are known to play an important role in enriching the harmonic content of an audio signal. However, despite the abundant research that has been devoted to the characterization of nonlinearities in the context of virtual analog modeling over the years, the discrete-time simulation of circuits exhibiting rate-dependent hysteretic phenomena remains an open challenge. In this article, we present a novel data-driven approach for the wave digital modeling of rate-dependent hysteresis using recurrent neural networks (RNNs). Thanks to the modularity of wave digital filters, we are able to locally characterize the wave scattering relations of a hysteretic reluctance by encapsulating an RNN-based model into a single one-port wave digital block. Hence, we successfully apply the proposed methodology to the emulation of the output stage of a vacuum-tube guitar amplifier featuring a nonlinear transformer.

Using gallium nitride (GaN) transistors in motor drive systems presents challenges because of their high dv / dt characteristics. Compared with silicon (Si) transistors, GaN transistors cause a higher leakage current in the bearing. This phenomenon results in a bearing corrosion problem in the motor, consequently shortening its lifespan. In response to these challenges, an output filter placed between an inverter and the motor has been studied recently. This paper compares the leakage current in a permanent magnet synchronous motor (PMSM) drive system driven by a GaN inverter without and with a sine wave filter. By modeling the impedance of the leakage current path, this paper confirms the possibility of reducing leakage current with the application of the sine wave filter. Experimental results show that using the sine wave filter reduces the leakage current by 32.24% at full load.

<p><b> An essential guide to the background, design, and application of common-mode filtering structures in modern high-speed differential communication links </b> <p> Written by a team of experts in the field, <i>Electromagnetic Bandgap (EBG) Structures</i> explores the practical electromagnetic bandgap based common mode filters for power integrity applications and covers the theoretical and practical design approaches for common mode filtering in high-speed printed circuit boards, especially for boards in high data-rate systems. The authors describe the classic applications of electromagnetic bandgap (EBG) structures and the phenomena of common mode generation in high-speed digital boards. <p> The text also explores the fundamental electromagnetic mechanisms of the functioning of planar EBGs and considers the impact of planar EBGs on the digital signal propagation of single ended and differential interconnects routed on top or between EBGs. The authors examine the concept, design, and modeling of EBG common mode filters in their two forms: on-board and removable. They also provide several comparisons between measurement and electromagnetic simulations that validate the proposed EBG filters' design approach. This important resource: <ul> <li>Presents information on planar EBG-based common mode filters for high-speed differential digital systems</li> <li>Provides systematic analysis of the fundamental mechanisms of planar EBG structures</li> <li>Offers detailed design methodology to create EBG filters without the need for repeated full-wave electromagnetic analysis</li> <li>Demonstrates techniques for use in practical real-world designs</li> </ul> <br> <p><i> Electromagnetic Bandgap (EBG) Structures: Common Mode Filters for High-Speed Digital Systems</i> offers an introduction to the background, design, and application of common-mode filtering structures in modern high-speed differential communication links, a critical issue in high-speed and high-performance systems.

Photodetection over a broad spectral range is necessary for multispectral sensing and imaging. Despite the fact that broadband single-element detectors with high performance have been demonstrated with various low-dimensional materials, broadband focal plane array imagers have been rarely reported. Here we propose a stacked lead sulfide/mercury telluride colloidal quantum dot photodetector configuration with optimized graded energy gaps. This architecture allows for ultrabroadband spectral response from 0.4 to 5.0 µm, with responsivity values of 0.23, 0.31, 0.83 and 0.71 A W −1 at 0.4, 0.7, 2.2 and 4.2 µm, respectively. We also fabricate a focal plane array imager with a resolution of 640 × 512, a low photoresponse non-uniformity down to 6% and a noise equivalent temperature difference as low as 34 mK. We demonstrate broadband imaging by simultaneously capturing both short-wave infrared and mid-wave infrared information, as well as multispectral imaging in the red, green, blue, short-wave infrared and mid-wave infrared channels, using a set of optical filters. Graded-energy-gap lead sulfide/mercury telluride stacked quantum dots enable photodetection and imaging in a focal plane array configuration from the visible (0.4 µm) to the mid-wave infrared (about 5 µm) region.

We present an ultra-compact single-shot spectrometer on silicon platform for sparse spectrum reconstruction. It consists of 32 stratified waveguide filters (SWFs) with diverse transmission spectra for sampling the unknown spectrum of the input signal and a specially designed ultra-compact structure for splitting the incident signal into those 32 filters with low power imbalance. Each SWF has a footprint less than 1 µm × 30 µm, while the 1 × 32 splitter and 32 filters in total occupy an area of about 35 µm × 260 µm, which to the best of our knowledge, is the smallest footprint spectrometer realized on silicon photonic platform. Experimental characteristics of the fabricated spectrometer demonstrate a broad operating bandwidth of 180 nm centered at 1550 nm and narrowband peaks with 0.45 nm Full-Width-Half-Maximum (FWHM) can be clearly resolved. This concept can also be implemented using other material platforms for operation in optical spectral bands of interest for various applications. Compact spectrometers that are simple and scalable in design can enable many applications. Here the authors demonstrate a silicon photonics based single-shot spectrometer that uses a group of waveguide frequency filters to construct the spectrum.