基于BJT和JFET的AGC电路的设计和实现

设计了自动增益控制电路,能够使放大电路的增益自动随信号强度的变化而调整。该电路通过采用改变BJT的直流工作状态来改变BJT的电流放大系数β,实现电阻分压以及改变JFET的栅源电压来控制放大器电阻的大小。设计的自动增益控制电路阐述了BJT分压、JFET变阻以及AGC电路的工作原理,实现了可控增益范围大约为40dB,对现实教学和应用都有很好的借鉴意义。     

CPU电源电路用沟槽栅MOSFET与e-JFET开关管的功耗对比

本文主要针对低压功率开关管的功耗进行了理论分析，并在此基础上分别对两种典型结构的沟槽栅MOSFET和e—JFET在不同工作频率下的功耗分布和总功耗进行了定量的仿真计算和对比。通过研究发现，在一定工作条件下，常闭型e-JFET比目前常用的沟槽栅型MOSFET仅开关功耗就降低约24％，总功耗则降低约30％。将其运用于CPU电源电路中的开关功率管的制造，在高频领域有着极好的应用前景。     

THEORETICAL ANALYSIS OF THE PRESSUREMAGNETO-ELECTRIC EFFECT OF JFET

In this paper the pressure-magneto-electric effect of Junction Field Effect Transistor(JFET)is discussed by using standard relaxation techniques.A theoretical evaluation of thepressure sensitivity and Hall sensitivity of the n-channel silicon JFET with various geometries(W/L),gate voltages(V_(FS))and drain voltages(V_(DS))is made.The results show that whenP≠0,B=0,the current-pressure sensitivity is about 2.5%.cm~2/N,supposing W/L(?)1/2-1.Based on that,a junction field effect pressure sensor with high stability and low noise is designed.     

一款JFET低噪声前置放大器的设计

在对级联网络及结型场效应管的噪声分析基础上,采用结型场效应管等分立元件设计了一款低噪声前置放大器实用电路。并对其幅频特性、输入阻抗和等效输入噪声进行了测量,结果表明其输入阻抗高达71Mn。等效输入噪声电压为0．7nV／√Hz,是一种适合于较高内阻传感器的较理想的低噪声前置放大器电路。     

VDMOS场效应晶体管电路模型的构造及参数提取

从VDMOS的物理结构出发建立子电路模型,进而导出描述其交直流特性的参数及模型公式.相对以往文献的结果,该模型避免了过多工艺参数的引入,同时对子电路进行了有效的简化.在参数提取软件中的加载结果表明,该模型结构简单,运算速度快,物理概念清晰,拟合曲线与测试数据符合精度高(直流误差5%以内,交流误差10%以内),适于在电路模拟及参数提取软件中应用.     

A Superconducting Cold-Electron Bolometer with SIS’ and Josephson Tunnel Junctions

A novel concept of a Superconducting Cold-Electron Bolometer (SCEB) with Superconductor-Insulator-Weak Superconductor (SIS’) Tunnel Junction and Josephson Junction has been proposed. The main innovation of this concept is utilizing the Josephson Junction for DC and HF contacts, and for thermal isolation. The SIS’ junction is used also for electron cooling and dc readout of the signal. The SIS’ junction is designed in loop geometry for suppression of the critical current by a weak magnetic field. The key moment of this concept is that the critical current of the Josephson junction is not suppressed by this weak magnetic field and can be used for dc contact. Due to this innovation, a robust two layer technology can be used for fabrication of reliable structures. A direct connection of SCEBs to a 4-probe antenna has been proposed for effective RF coupling.      

1200V大容量SiC MOSFET器件研制

采用平面栅MOSFET器件结构,结合优化终端场限环设计、栅极bus-bar设计、JFET注入设计以及栅氧工艺技术,基于自主碳化硅工艺加工平台,研制了1200V大容量SiC MOSFET器件.测试结果表明,器件栅极击穿电压大于55V,并且实现了较低的栅氧界面态密度.室温下,器件阈值电压为2.7V,单芯片电流输出能力达到50A,器件最大击穿电压达到1600V.在175℃下,器件阈值电压漂移量小于0.8V;栅极偏置20V下,泄漏电流小于45nA.研制器件显示出优良的电学特性,具备高温大电流SiC芯片领域的应用潜力.     

结型场效应晶体管放大器的噪声

本文通过分析结型场效应管(JFET)放大器内部不同的噪声源，首次导出了场效应管放大器在较宽频率范围内的等效输入噪声电压表达式，估算了当信号源阻抗为容性时JFET放大器的总噪声，为场效应管电路低噪声优化设计提供有力的工具。     

Solid-State Circuit Breaker Based on Cascaded Normally-On SiC JFETs for Medium-Voltage DC Distribution Networks

Solid-state circuit breakers (SSCBs) are critical components in the protection of medium-voltage DC distribution networks to facilitate arc-free, fast and reliable isolation of DC faults. However, limited by the capacity of a single semiconductor device, using semiconductor-based SSCBs at high voltage is challenging. This study presents the details of a 1.5 kV, 63 A medium-voltage SSCB, composed primarily of a solid-state switch based on three cascaded normally-on silicon carbide (SiC) junction field-effect transistors (JFETs) and a low-cost programmable gate drive circuit. Dynamic and static voltage sharing among the cascaded SiC JFETs of the SSCB during fault isolation is realized using the proposed gate drive circuit. The selection conditions for the key parameters of the SSCB gate driver are also analyzed. Additionally, an improved pulse-width modulation current-limiting protection solution is proposed to identify the permanent overcurrent and transient inrush current associated with capacitive load startup in a DC distribution network. Using the developed SSCB prototype and the fault test system, experimental results are obtained to validate the fault response performance of the SSCB.     

高压工艺N阱电阻SPICE模型研究

文章对0.5μm/40V高压工艺中形成的N阱电阻的SPICE模型进行研究。因为高压电路的实际应用,N阱电阻的寄生效应不可忽略,所以精确反应其电学特性的SPICE模型也显得尤为重要。从N阱电阻的测量结果反映其IV曲线的非线性特性和结型栅场效应管JFET输出特性曲线具有相似性,并通过对高压阱电阻与JFET的结构分析认为可以采用JFET的电压电流关系来建立合理的数学模型反映高压阱电阻的这种非线性特性。因此在文中借用JFET的SPICE模型作为基础,用宏模型的方法为高压N阱电阻建立了一套精确的SPICE模型。此模型适用于各类仿真器,具有一定的通用性。