基于SG3525A的半桥式开关电源

开关电源以其轻小高效的特点在很多方面得到了广泛应用,市场广阔。文中介绍了DC/DC变换器主电路的分类,分析了半桥型DC/DC变换器的构成,并深入分析了其工作原理、工作过程,分析总结了其相对于其他类型DC/DC变换器拓扑的优点。对开关电源的控制方式进行了比较,给出了集成控制器的优点,同时给出了电压型集成控制器SG3525A的内部结构、管脚功能,详细分析其工作原理、应用和优点。设计了一款基于SG3525A的半桥式开关电源,给出其工作原理、过程,尤其深入分析了由SG3525A构成的控制电路;实验结果表明,该电源具有效率高、电压调整率和负载调整率高、稳定可靠等优点。     

The effects of substrate bias,substrate temperature,and pulse frequency on the microstructures of chromium nitride coatings deposited by pulsed direct current reactive magnetron sputtering

Recently, great attention has been devoted to the pulsed direct current (DC) reactive magnetron sputtering technique, due to its ability to reduce arcing and target poisoning, and its capability of producing insulating thin films. In this study, chromium nitride (CrN) coatings were deposited by the bipolar symmetric pulsed DC magnetron reactive sputtering process at different pulse frequency, substrate bias voltage, and the substrate temperature. It was observed that the texture of CrN changed from (111) to (200) as substrate temperature increased to 300°C as deposited at 2 kHz without substrate bias. With increasing pulsing bias and pulse frequency of target, predominated (200) orientation of CrN film was shown due to the ion bombardment/channeling effect to preferentially sputter those unaligned planes. For the CrN coatings deposited with pulsed biasing, the grain size decreased with increasing pulse frequency and substrate bias, whereas the surface roughness showed a reverse trend. The deposition rate of the CrN films decreased with increasing pulse frequency. It was concluded that the pulse frequency, substrate bias, and substrate temperature played important role in the texture, microstructure, and surface roughness of the CrN coatings deposited by the pulsed DC magnetron sputtering process.     

一种具有双模检测功能和高稳定性的唤醒接收机基带电路

This paper proposes a baseband circuit for wake-up receivers with double-mode detection and enhanced sensitivity robustness for use in the electronic toll collection system.A double-mode detection method,including amplitude detection and frequency detection,is proposed to reject interference and reduce false wake-ups.An improved closed-loop band-pass filter and a DC offset cancellation technique are also newly introduced to enhance the sensitivity robustness.The circuit is fabricated in TSMC 0.18μm 3.3 V CMOS technology with an area of 0.12 mm2.Measurement results show that the sensitivity is -54.5 dBm with only a±0.95 dBm variation from the 1.8 to 3.3 V power supply,and that the temperature variation of the sensitivity is±1.4 dBm from -50 to 100℃. The current consumption is 1.4 to 1.7μA under a 1.8 to 3.3 V power supply.     

基于模糊控制的有源滤波器直流母线电压控制

针对传统直流侧电压控制方法存在超调量和静差较大的问题,设计了混合有源电力滤波器控制系统,建立了混合有源电力滤波器的系统模型,并针对直流侧电压控制设计了一套双模糊控制器,与传统直流侧电压控制方法相比,该控制方法具有超调小、响应速度快、静差较小的特点。仿真结果验证了该方法的正确性和可行性。     

功率器件IGBT槽栅设计尺寸对直流参数影响的研究

IGBT由于其优异特性而广泛应用于电机、电焊机和功率开关等领域,是功率器件的主流产品之一。本文首先简要介绍IGBT及历代器件工艺的发展,提出了一种槽栅IGBT的工艺流程,并研究了其槽栅设计尺寸对器件主要直流参数的影响。     

自动尿液分析仪系统设计

介绍了基于干化学法的尿液分析仪研制以及系统组成,并对系统误差进行了分析。分析仪利用红、绿、蓝LED灯作为光源对不同的试纸块进行照射,利用光电池和信号调理电路将反射光转换为相对应的电压信号,输出信号与分析仪预存的阈值比较得出检验结果。利用STM32F103ZET6作为分析仪的控制单元,通过D/A转换器输出直流电压作为信号调理电路的直流偏置电压,以补偿环境光和元件所产生的误差。理论分析与实验数据表明,该补偿方式取得了较好的效果。     

1.25Gb/s CMOS高灵敏度宽动态范围跨阻放大器

采用0.35μm CMOS工艺设计并实现了一种新的应用于1.25Gb/s光纤通信接收机的高灵敏度、宽动态范围跨阻放大器电路。引入电流注入技术提高输入管跨导、优化噪声性能、提高灵敏度。自带直流反馈实现直流消除功能,同时采用自动增益控制机制,提高动态范围。仿真结果表明,该电路具有82.02dBΩ的跨阻增益、872.7MHz的带宽、23.74kHz的低频截止频率,输入等效噪声电流为4.08pA/Hz(1/2),最大输入光信号为+3dBm(2mA),在3.3V的电源电压下,芯片功耗为43.4mW。     

一种带有ARINC429输出功能的直流电压比率表设计

航空维修企业使用的直流电压比率表非常昂贵并且用途专一,采用低成本的MSP430F1611单片机为控制器设计了量程自动转换的数字电压表,可以自动测量200V以内直流电压。在此基础上实现了直流电压比率的测量和显示。采用HS3282和HS3182芯片,将直流电压比率信号转换成串行的ARINC429数据格式。数字电压比率和ARINC429数据输出测试表明,电压比率表转换精度相对较高,ARINC429数据稳定可靠,可以在航空维修、自动测试中广泛使用。     

基于PSpice的光伏并网系统仿真研究

采用DC／DC和DC／AC两级拓扑结构对光伏并网系统进行了研究和设计,采用改进的定电压跟踪法（CVT）实现最大功率点闭环跟踪,并将PWM控制器引入并网逆变中,采用三角波比较方式实现SPWM电压逆变和输出电流的波形跟踪与控制,在电压、电流内环的基础上引入功率外环以实现系统前后级功率平衡和能量管理,采用基于PSpice的光伏电池仿真模型对所设计光伏并网系统进行了仿真。仿真结果表明,基于PSpice的光伏仿真模型能够有效地模拟实际光伏并网系统的行为特征,将PSpice软件用于光伏发电系统的仿真是可行的。     

引出结构对叠层片式电感器可靠性影响的研究

叠层片式电感器(MLCI)其引出结构在热应力冲击下,可能会形成开路,降低了MLCI的可靠性,进而影响到电子线路的整体功能。针对实际应用过程中一例叠层片式电感器(型号CH1608H22N)的失效,采用X射线检查、金相检查等分析方法对电感器的失效机理进行了分析。结果表明引出电极与内电极结合部位的热致失效导致了开路,进而研究了引出结构对MLCI可靠性的影响,设计出了一种新的圆弧型引出结构,通过实验验证该结构的耐流特性比直角型引出结构的提高了50%,产品可靠性得以改善。