Near-field wireless MIMO (NFWMIMO) links are a promising solution for chip-to-chip and board-level communication at millimeter-wave frequencies. However, their performance is severely limited by strong mutual coupling and impedance mismatch due to subwavelength antenna spacing. This study presents a circuit-theoretic framework and a practical design methodology for decoupling and matching networks (DMNs) applied to dense NFWMIMO dipole arrays operating at 30 GHz. Mutual coupling is analyzed using impedance and scattering parameter formulations, along with multiport network theory. LC-based DMNs are designed for both 2 & times; 2 and 4 & times; 4 dipole arrays over the 24-36-GHz band using full-wave simulations in Altair Feko and network synthesis in Optenni Lab. The results demonstrate a substantial reduction in mutual coupling, with isolation improvements exceeding 30 dB for dominant coupling paths in the 2 & times; 2 configuration and notable suppression observed in selected paths of the 4 & times; 4 array. A trade-off in impedance matching is observed in higher-order arrays due to increased coupling complexity. Key MIMO performance metrics, including ECC, diversity gain (DG), and total active reflection coefficient (TARC), show improved behavior after applying the DMN. A fabricated prototype validates the antenna performance, showing reasonable agreement between simulated and measured results. The proposed approach provides a practical solution for enhancing NFWMIMO system performance in compact millimeter-wave environments.
This work presents a novel frequency compensation method for four-stage CMOS amplifiers, addressing the complexity and instability challenges prevalent in modern low-voltage, low-power electronic systems. The proposed approach employs nested differential gain stages combined with a single, compact Miller capacitor at the common output, which enables efficient frequency compensation while minimizing chip area and power consumption. The amplifier benefits from the topological advantages of differential stage integration, allowing the Miller effect to be virtually amplified across multiple feedback loops and facilitating the use of a smaller compensation capacitor. The linear transfer function (TF) of the design is meticulously derived through symbolic computation and then validated against circuit-level simulations performed with 0.18 mu m CMOS technology. Results demonstrate a strong agreement between theoretical and simulated data, with the amplifier achieving exceptional performance metrics: a DC gain of 122 dB, a gain-bandwidth product (GBW) of 4.1 MHz, and a phase margin (PM) of 89 degrees, while consuming less than 360 mu W. Robustness is verified across process corners and through Monte Carlo analysis, confirming consistent performance under varying load capacitance and design parameters. Overall, this work presents an efficient and scalable compensation technique suitable for next-generation analog and mixed-signal applications.
Due to the influence of the magnetostrictive effect of silicon steel sheet, the core inevitably generates vibration in the working process of the transformer, and at the same time, there are differences in the magnetostrictive properties of silicon steel sheet in the rolling and vertical rolling directions, so the core has anisotropic characteristics, and the effects of anisotropy of the iron core are taken into consideration in the simulation, and the simulation results can be more accurate. In this paper, the magnetostrictive measurement system is used to measure the magnetostrictive properties of silicon steel sheet in the rolling and perpendicular rolling direction and analyze the differences in the magnetostrictive properties of silicon steel sheet in the rolling and perpendicular rolling direction, and based on the measured data of silicon steel sheet, a three-phase transformer for the multiphysical field coupling model has been studied. The simulated results show that the stress and deformation of the corner area and the joints of the core are larger than the other regions. The displacement of the core gradually decreases from the upper left corner of the core toward the corner area, and in the T-type area of the core, the displacement of the core first rises and then decreases as the position goes deeper into the direction of the corner area, with the displacement of the corners of the core being the largest from an overall point of view.
Aiming at the existing handwritten digit recognition systems with low recognition accuracy, high system power consumption, and high hardware resource consumption, this paper proposes a low-power, high-precision, and lightweight handwritten digit recognition hardware acceleration scheme for multiscenario based on FPGA. By optimizing the network structure of a convolutional neural network (CNN) and the number of parameters of the model, this scheme proposes a high-precision and lightweight network model, simplified CNN, and by optimizing the data access mode and memory usage, and by adopting the strategies of time-sharing and multiplexing, weights sharing, and parallel processing for the hardware acceleration of the algorithm, it effectively reduces the consumption of hardware resources and improves the performance of the system. The experimental results show that the recognition accuracy of the algorithm reaches 98.82%, the system response time is 0.481316 ms under the 33 + 200 MHz system clock, and the on-chip power consumption of the system is 0.843 W, and it can be used for real-time handwritten digit recognition in many occasions.
In this research, the performance of an inductive modulator during energy injection into a straight rod plasma antenna, activated using a DC electric discharge, has been experimentally investigated. The primary focus of this study is on correcting one of the parameters of the inductive modulator, specifically its ohmic resistance. The variations in the ohmic resistance of the modulator with respect to frequency in the very low frequency (VLF) range, between 100 kHz and 50 MHz, are analyzed. This analysis is conducted under varying pressures within the plasma antenna tube. Additionally, the effect of the modulator’s position, whether near or far from the cathode, on the modified ohmic resistance variations is examined and simulated in this study.
