Current Issue : October-December Volume : 2026 Issue Number : 4 Articles : 5 Articles
This paper investigates the impact of the quasi-square wave zero voltage switching (QSW-ZVS) technique on the design of passive electromagnetic interference (EMI) filters for DC-DC buck converters. A standard design-oriented analysis is conducted, focusing on a single-stage LC EMI filter with a single-resistor shunt damping network Rd-C d, aiming to minimize the impact of the filter on the small-signal dynamic of the converter. We demonstrate that QSW-ZVS enables a reduction in the size of the damping network of the EMI filter when compared with conventional hard-switching designs. Furthermore, we generalize the proposed analysis to different EMI filter cutoff frequencies, evaluating how the value of the shunt damping capacitance Cd varies when QSW-ZVS is enabled. Both the proposed small-signal model and the design methodology are validated with SIMPLIS simulations under various operating conditions of a DC-DC buck converter....
Metallisation of semiconductor and dielectric-coated semiconductor surfaces is a key step in device production, such as in the fabrication of photovoltaic solar cells. Metal deposition can, however, be detrimental to the dielectric, interface and underlying substrate quality. This work studies damage created by thermal and electron-beam evaporation of metals on silicon passivated with thin dielectric layers. Metals are deposited on one side of silicon samples coated with aluminium oxide grown by atomic layer deposition with different thicknesses (∼1–25 nm). Samples are characterised from the other side using photoluminescence (PL) imaging with the radiative PL signal being highly sensitive to charge carrier density and thereby effective charge carrier lifetime. We find that thermal evaporation of aluminium can degrade the PL signal when the aluminium oxide films are 5 nm or thinner. In some cases, annealing at 400 ◦C in forming gas provides a partial repair of the damage. By performing superacid re-passivation experiments on previously metallised samples, we find that the damage is shallower than ∼6 μm from the surface. Electron-beam evaporation of metals, including aluminium, reduces the effective lifetime even in samples with ∼25 nm thick Al2O3 passivation layers. With electron-beam evaporation, annealing in forming gas at 400 ◦C only repairs the damage when the Al2O3 films are ⩾20 nm thick, with the damage in thinner films shown to be >3 μm deep into the silicon. This work shows that the choice of process used for metal contact deposition can affect the properties of the sample structure under investigation....
Surface-emitting distributed-feedback (SE-DFB) semiconductor lasers based on secondorder gratings face a fundamental triple constraint: the spatial co-location of gain, grating feedback, and vertical radiation functions limits single-mode selectivity, surface extraction efficiency, and far-field beam quality simultaneously. We propose a quasi-parity-time (PT)- symmetric SE-DFB laser with separated gain and radiating-grating sections. In this design, the electrically injected gain section and the passive second-order grating section are placed in different regions along the cavity axis, thereby separating electrical injection from surface emission without epitaxial regrowth. Coupled-mode theory and two-dimensional finiteelement simulations demonstrate that the resulting longitudinal non-Hermitian gain–loss asymmetry produces spatial-overlap-dependent threshold discrimination, enabling an isolated low-threshold lasing branch that remains separated from competing cavity modes over the investigated pump-parameter range. Under the HR–AR boundary condition, the proposed design achieves a threshold gain margin of Δg = 12.4 cm−1, more than six times that of a conventional HR–AR DFB benchmark considered here, together with an upward surface extraction efficiency of 23.4% obtained from 2D FEM simulations. A simplified steady-state rate-equation estimate further suggests that the increased threshold margin can support strong side-mode suppression. The design imposes no regrowth requirement and is fully compatible with standard single-growth InP ridge-waveguide fabrication....
One of the causes of global boiling, which has been inducing abnormal weather around the world, is the enormous power consumption of data centers, especially in arithmetic logic unit (ALU) operations and memory data transfers. We aim to achieve ultralow-power consumption by replacing Si-based cache memories with analog in-memory computing (AiMC) and randomaccess memories using crystal indium oxide, which enables field-effect transistors (FETs) with excellent on-state characteristics, including a mobility of up to 142.7 cm2 /V s, and an off current lower than that of a Si FET by 11 orders of magnitude. We are also studying ultralow-power artificial intelligence (AI) ALUs using AiMC FETs in the subthreshold regime. This report will introduce the trend of these technologies. Further development of devices based on these technologies will achieve high integration and power saving, which is expected to be important countermeasures against global boiling....
Terahertz (THz) technology undergoes rapid progress in recent years, drawing increasing attention to THz integrated circuits (ICs) in response to the trend of integration and the demand for system miniaturization. Since the component dimensions become comparable to the operating wavelength, the parasitic effects become more pronounced, and phase inhomogeneity in the circuit introduces challenges. These effects restrict the applicability of conventional microwave IC designing strategies in the THz regime. Spoof surface plasmon polaritons (SSPPs) offer a promising solution for THz ICs, owing to their superior properties such as strong field confinement and near-field enhancement, which enable novel transmission and modulation mechanisms. This study reviews the fundamental principles of SSPPs, highlights recent advances in both propagating and localized SSPP circuits and systems, and emphasizes their integration to THz ICs. The paper aims to provide new perspectives for the development ofTHz ICs....
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