Electronics Letters最新文献

Measurement of the temperature in an integrated circuit (IC) is essential for evaluating temperature-dependent circuit performance. Using off-chip temperature sensors for this purpose has limited accuracy in sensing the on-chip temperature. For on-chip integration with ICs, a low-power and compact temperature sensor is required. Therefore, this letter presents a 2-Transistor (2T) voltage reference generator (VRG) that overcomes the limited sensitivity of conventional structures through the deep-subthreshold operation and achieves high $�T$–$�V$ sensitivity by employing the narrow-width effect. The proposed 2T VRGs are implemented in 28-nm FD-SOI process and demonstrated to operate over a temperature range of 200 to 400 K, achieving a 0.86 mV/K $�T$–$�V$ sensitivity with 3.6% relative inaccuracy.

A novel higher order local time-stepping (LTS) technique for the discontinuous Galerkin time-domain–finite difference time-domain (DGTD–FDTD) method is proposed to accelerate transient electromagnetic simulations. The higher order equation is applied to the boundary elements or grids between LTS classes to reduce approximation error caused by the LTS. The proposed higher order LTS is incorporated in DGTD–FDTD to avoid the global decrease of the minimum time step and thus boost simulation efficiency, which has not been studied before. Through one numerical example, the accuracy and efficiency of the presented method are demonstrated, showing its ability to model practical multiscale targets.

A resource-efficient semi-analytical method for mechanical fault detection via acoustic signal analysis is presented. A compact signal portrait is constructed by tracking dominant salient-frequency peaks over time, without a priori assumptions on peak locations. Peak feature statistics are aggregated into a 3D matrix that encodes nominal oscillatory modes. Fault detection is achieved by measuring the deviation between current and healthy portraits using a single decision threshold. Experiments on internal combustion engine recordings demonstrate improved separability and lower computational cost compared to empirical mode decomposition, confirming suitability for resource-constrained monitoring.

A miniaturised quarter-mode substrate-integrated waveguide (QMSIW) bandpass filter based on a curved slot is introduced in this paper. The proposed filter is designed by etching a sinusoidal curved slot on the top layer of the structure. Compared with the QMSIW loading conventional slots structure, the sinusoidal curved slot QMSIW filter uses a periodic structure of distributed capacitance, thereby further reducing of filter by about 22% size. Simulation and experimental results show reasonable agreement.

We present a digital holography method for measuring the dispersive properties of semiconductor laser waveguides. The approach is based on low-coherence off-axis holography and enables the determination of wavelength-dependent group delay and group index with high accuracy. In a wavelength range of 830–870 nm, the optical path difference is evaluated through the degree of coherence between object and reference waves. Compared to existing interferometric techniques, the method allows flexible measurements outside of integrated devices and avoids aliasing artifacts in spectroscopic approaches. Experimental results obtained with InGaAsP-based semiconductor lasers show good agreement with theoretical models and demonstrate the suitability of this technique for dispersion characterization. In addition, the setup can be extended to measure other key laser parameters, such as carrier-induced refractive index changes, offering a versatile tool for semiconductor laser analysis.

Aiming at the interference issue between Beidou RDSS and 5G systems operating in adjacent frequency bands, this letter analyses the stability of RDSS performance under complex urban network environments. With expanding urban networks and more complex deployment patterns, Beidou users experience more uncertain interference, making it necessary to analyse base-station switching during user movement to ensure stable system performance. To address this issue, this letter employs different point distribution models to simulate various network models and describe the interference situations of Beidou users when traversing 5G cellular networks. The research identifies the most suitable network model and examines interference fluctuations for both static and dynamic users, which is important for the compatible coexistence of the Beidou and 5G systems.

A simplified stochastic model for microwave modulation transfer, based on wave solutions of the telegrapher's equation, is quantitatively validated against experimental signal amplitude data. With physically plausible parameters, the model accurately reproduces observed behaviors through both analytical fitting and Random Forest regression, achieving RMSE = 0.069 and R² = 0.944. By integrating stochastic transport effects with wave-based interpretations, the framework offers a unified perspective that extends beyond classical electromagnetic models. These results confirm the model's robustness and highlight its potential for broader applications in signal propagation analysis.

The ambiguity function (AF) plays a critical role in joint communication and sensing (JCAS) systems. In this letter, we design a novel JCAS waveform and analyze its AF characteristics. The cut view of the AF, it is observed that the modulation and variation of communication data do not affect the zeros-delay cut, while the zero-Doppler cut changes with the modulation data. Since variations in zero-Doppler cut lead to unnecessary fluctuations and higher sidelobe levels, optimizing zero-Doppler cut for a more concentrated mainlobe and sidelobe suppression is crucial. Based on this insight, we develop a hybrid optimization algorithm, termed QGPV. It integrates the quantum genetic algorithm (QGA), quantum particle swarm optimization (QPSO), and the variable neighborhood search (VNS). The proposed algorithm QGPV reduces the sidelobe level and improves the overall resolution performance. Simulation results show that the optimized waveform achieves excellent delay and Doppler resolution, making it suitable for JCAS applications.

In low-altitude integrated sensing and communication systems, unmanned aerial vehicles mobility induces highly time-varying and non-stationary channels, where pilot-based or static-assumption methods fail to ensure reliable channel estimation. This paper proposes a channel estimation method combining spatio-temporal structure with conditional generative adversarial network. The U-shaped convolutional neural network is used for channel spatial feature extraction and high-precision reconstruction, while skip connections preserve fine-grained details. Furthermore, a long short-term memory network is integrated to model the temporal dynamic evolution of the channel, enhancing adaptability to non-stationary environments. A conditional adversarial training with a PatchGAN-based discriminator is introduced to improve local realism and distribution approximation. Simulation results confirm that the proposed method significantly improves estimation accuracy and robustness in low-altitude scenarios.

Proximal policy optimization (PPO) is a widely used reinforcement learning algorithm valued for its robustness and sample efficiency. Its success is often attributed to the actor's clipped loss, which keeps policy updates within a trust region. In contrast, the critic's clipped loss has received relatively little attention, leaving its consistency with the trust-region principle unclear. To bridge this gap, we analyze the critic's clipped loss, show its misalignment, and propose a refined loss that enforces trust-region compliance by construction. Experiments on continuous-control tasks confirm that the proposed method improves adherence to the trust region.