- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2018 IEEE Biomedical Circuits and Systems Conference (BioCAS) - Cleveland, OH, USA (2018.10.17-2018.10.19)] 2018 IEEE Biomedical Circuits and Systems Conference (BioCAS) - Multi-coil High Efficiency Wireless Charger System for Hermetically Sealed Biomedical Implants
摘要： Biomedical inductively-coupled transcutaneous implants with internal batteries typically rely on a two-coil charging system which places fundamental and practical limits such as requiring short coil-to-coil distance for useful Wireless Power Transfer (WPT) efficiency. In case of hermetic metal enclosures equipped with finite size dielectric window for magnetic flux penetration, two-coil configurations can induce substantial additional loss due to eddy currents generated on e.g. Ti metal surface by fringing B-fields. Dissipative losses are unwelcome as they increase the temperature of the implant. We focus here on high-performance implants with internal electronic circuits and power source which require frequent, rapid battery recharging. The case example is a wireless broadband neural recording device capable of high data rate transmission (> 40 Mbps). We describe a compact planar four-coil configuration to achieve efficient Wireless Power Transfer (WPT) across tissue layers exceeding 1 cm. For the device geometry discussed here, our system transfers up to 73 % and 46 % of RF energy across 16 mm-separated source-to-load coil, in absence or presence of a Ti-enclosure which embeds the energy harvesting coil pair respectively. Thin sheets of ferrites are integrated to enhance local B-fields. We are able to charge a 200 mAh medical-grade battery to useful 84% of its full charge capacity (near current saturation) within 1 hour through a sapphire window integrated with the hermetic Ti- enclosure. The measured temperature increase is 2.1 ℃ with Ti-can immersed in still saline, slightly above FDA requirements or more recent ISO standards. From physiological models, we expect that active cooling by body tissue surrounding the implant (such as microvasculature perfusion) will provide for a safe and efficient WPT method.
关键词： biomedical implants,inductive charging,Eddy current heating,wireless charging
更新于2025-09-23 15:23:52
-
Topological valley pumping in Weyl semimetals
摘要： We investigate the topological pumping effect in Weyl semimetals, subject to the modulation of two ac electric fields along y and z directions, respectively. We show that the pumping effect originates from the anomalous velocity related to the Berry curvature. The direction of the pumping current is dependent on the chirality of the Weyl fermions. While the total particle current is vanishing because the Weyl points of opposite chirality always come in pairs in Weyl semimetals, the pump gives rise to a net chirality current or valley current. The noiseless valley current generated can be useful in valleytronic applications.
关键词： Valleytronics,Chirality,Topological pumping effect,Valley current,Weyl semimetal
更新于2025-09-23 15:23:52
-
Impact of strained silicon on the device performance of a bipolar charge plasma transistor
摘要： In this manuscript we analyze a unique approach to improve the performance of the bipolar charge plasma transistor (BCPT) by introducing a strained Si/SixGe1?x layer as the active device region. For charge plasma realization different metal work-function electrodes are used to induce n+ and p+ regions on undoped strained silicon-on-insulator (sSOI or SixGe1?x) to realize emitter, base, and collector regions of the BCPT. Here, by using a calibrated 2-D TCAD simulation the impact of a Si mole fraction x (in SixGe1?x) on device performance metrics is investigated. The analysis demonstrates the band gap lowering with decreasing Si content or effective strain on the Si layer, and its subsequent advantages. This work reports a significant improvement in current gain, cutoff frequency, and lower collector breakdown voltage (BVCEO) for the proposed structure over the conventional device. The effect of varying temperature on the strained Si layer and its implications on the device performance is also investigated. The analysis demonstrates a fair device-level understanding and exhibits the immense potential of the SixGe1?x material as the device layer. In addition to this, using extensive 2-D mixed-mode TCAD simulation, a considerable improvement in switching transient times are also observed compared to its conventional counterpart.
关键词： bipolar charge plasma transistor (BCPT),mole fraction,cutoff frequency (fT),current gain (β),collector breakdown voltage (BVCEO),strained Si layer,band gap lowering
更新于2025-09-23 15:23:52
-
[IEEE 2018 IEEE International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD) - Tianjin, China (2018.4.15-2018.4.18)] 2018 IEEE International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD) - Experimental Study on the Twist Characteristics of Novel HTS Square Wire with Different Structures
摘要： This paper presents the characteristics of novel high temperature superconducting (HTS) twisted square wires with different structure. First, the HTS tapes of 4 mm width are cut into 1 mm width HTS narrow tapes. Then, different numbers of HTS narrow tapes and narrow tape of copper are stacked to prepare a HTS square wire with three structures of 1 + 5c, 2 + 4c and 4 + 2c. Finally, the HTS square wires of these three structures were twisted, and the critical current characteristics of HTS tapes were tested under different twist pitches. The test results show that the twist pitch of the three structures is about 100 mm. The experimental results show that the preparation of HTS square wire with twisted characteristic better, which has broad application prospects in superconducting power equipment.
关键词： twist pitch,critical current,Novel high temperature superconducting twisted square wires,superconducting filaments
更新于2025-09-23 15:23:52
-
[IEEE 2018 International IEEE Conference and workshop in óbuda on Electrical and Power Engineering (CANDO-EPE) - Budapest, Hungary (2018.11.20-2018.11.21)] 2018 International IEEE Conference and Workshop in óbuda on Electrical and Power Engineering (CANDO-EPE) - Plasma ignition and current control considerations for magnetron sputtering power supplies
摘要： Physical vapor deposition processes require different types of special power supplies for the ignition and sustaining of the plasma inside the sputtering chamber. The paper identifies some requirements for the design of a pulsed DC converter. Experiments have been carried out to identify the current-voltage characteristics of the vacuum chamber with the supply of different gases, and gas mixtures in the usable pressure domain. The vacuum chamber was supplied with voltage and current impulse trains with various parameters in order to acquire relevant data regarding the gas breakdown in pulsed power mode. A power electronic converter topology and control routine has been proposed, which is suitable for plasma ignition and discharge current control. The proof of concept has been demonstrated with the help of the magnetron sputtering chamber supplied by a test circuit.
关键词： current control,power electronic converter,plasma ignition,magnetron sputtering
更新于2025-09-23 15:23:52
-
[IEEE 2017 5th International Conference on Mechanical, Automotive and Materials Engineering (CMAME) - Guangzhou (2017.8.1-2017.8.3)] 2017 5th International Conference on Mechanical, Automotive and Materials Engineering (CMAME) - Modeling and Application of Output Current of the Solar Array for Satellite in Sun Synchronous Orbit
摘要： The output current of the solar array for satellite in sun synchronous orbit is a critical parameter for performance in-orbit analyzing. In order to analysis the rules of the solar array output current accurately, some influential factors, such as the incidence angle of the sun, the temperature of the solar array, the earth-sun distance factor and the fixed offset angle to the sun of solar wing, are comprehensively researched. Then a model of output current is established. Results in-orbit show that the model has high accuracy, which can provide a reference for optimization design of satellite solar array.
关键词： the solar array,modeling,output current,sun synchronous orbit,satellite
更新于2025-09-23 15:23:52
-
[IEEE 2018 IEEE International Conference on Electronics, Computing and Communication Technologies (CONECCT) - Bangalore (2018.3.16-2018.3.17)] 2018 IEEE International Conference on Electronics, Computing and Communication Technologies (CONECCT) - AlInN/GaN MIS-HEMTs with High Pressure Oxidized Aluminium as Gate Dielectric
摘要： AlInN/GaN metal insulator semiconductor high electron mobility transistor (MIS-HEMT) with high pressure oxidized aluminium as gate dielectric is investigated in this paper. The fabricated MIS-HEMT shows more than six orders of reduction in the gate leakage current in reverse bias and more than three orders of reduction in forward bias compared to the reference HEMT devices also fabricated on same substrates. A maximum drain current of 750 mA/mm was achieved due to improvement in the gate swing for MIS-HEMT. The MIS-HEMT devices also showed good improvement in the subthreshold slope and ID,ON/ID,OFF ratio compared to HEMT devices.
关键词： gate leakage current,MIS-HEMT,high pressure oxidation,AlInN/GaN,HEMT,Al2O3
更新于2025-09-23 15:23:52
-
[IEEE 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Performance Based Design of IMD for Single Stage PV Fed Water Pumping
摘要： This paper presents an improved designed induction motor, used for photovoltaic (PV) array fed water pumping system. The overall system is designed without a mechanical sensor to reduce both cost and complexity with simultaneous assurance of optimum power utilization of a PV array. The proposed system consists of an induction motor operated water pump, controlled by field-oriented control (FOC) with artificial neural network (ANN) current control technique. The MPPT (Maximum Power Point Tracking) as well as DC link voltage, is regulated by three-phase voltage source inverter (VSI). The estimation of motor speed eliminates the use of mechanical sensor and makes the system cheaper and robust. A new robust speed adaptive algorithm is presented, which is less dependent on parameters. A detailed study of various factors affecting the efficiency of the motor, is given to improve the behavior of the induction motor drive (IMD) for water pumping. The designed motor is tested on the developed prototype in the laboratory and its suitability is judged through various results under steady state and dynamic conditions of insolation variations.
关键词： Field-Oriented Control (FOC),Speed Adaptation,Finite Element Method,ANN Based Current Control,IMD (Induction Motor Drive),Water pump,PV Array,P&O Based MPPT Algorithm
更新于2025-09-23 15:23:52
-
[IEEE 2018 14th IEEE International Conference on Solid-State and Integrated Circuit Technology (ICSICT) - Qingdao, China (2018.10.31-2018.11.3)] 2018 14th IEEE International Conference on Solid-State and Integrated Circuit Technology (ICSICT) - Silicon Verification of Improved Nagata Current Mirrors
摘要： This paper describes silicon verification of our improved peaking current mirror, originally invented by Nagata Minoru in 1966. Our improved MOS current mirror circuits are insensitive to wide range of power supply voltage variation and they are realized by addition of multiple current peaks. We show chip design/measurement results, and their performance evaluation. The proposed circuits are simple (such as, no need for startup circuit), small yet well-insensitive to power supply voltage variations, and they can be widely used in analog ICs.
关键词： Peaking current mirror,Reference current source,Nagata current mirror,Supply voltage variation
更新于2025-09-23 15:22:29
-
Noise-optimized ultrastable low-noise current amplifier
摘要： We have developed a noise-optimized ultrastable low-noise current amplifier (ULCA) aimed at reducing the uncertainty at low currents. It involves a thin-film resistor network with 6.75 GΩ at the high-ohmic path which reduces the noise level to 1.6 fA/√Hz. Noise investigations as well as short-term and long-term stability studies were carried out. The stability of the input current gain was measured using a cryogenic current comparator at ±6.1 nA. Methods for investigating the measurement accuracy at low input currents of about 100 pA at a level of below one part in 10^7 are introduced and experimentally verified. The performance of the noise-optimized ULCA is compared with that of the standard variant introduced in 2014. It is shown that the reduced noise floor is achieved without impairing the stability of the transresistance.
关键词： low-current measurement,cryogenic current comparator,current amplifier,stability,noise optimization
更新于2025-09-23 15:22:29