基于多层PCB的三路威尔金森功分器设计

基于多层PCB工艺，提出了一种新型三路威尔金森功分器结构。在S频段设计了一个三路功分器实例，对其进行了电路、电磁场仿真分析，得到了较为理想的性能，并与理论值得到了较好的吻合。     

Design of a memcapacitor emulator based on a memristor

Since Hewlett-Packard?s solid state implementation of a memristive system in 2008, a lot of research has begun to develop applications using this new component. As it is not available as a two terminal device yet, emulating circuits must be developed. Building on our previous work to develop an analog model of a memristor, a memcapacitor emulator is proposed in this Letter. This model can be realized by transforming a memristor emulator to a memcapacitor emulator. The characteristics of a memcapacitor are based on the theory proposed by L.O. Chua. The transformation process is described in detail in this Letter. Simulation and experimental results are given as well.     

A Novel Unequal Broadband Out‐of‐Phase Power Divider Using DSPSLs

In this paper, a novel unequal broadband out‐of‐phase power divider (PD) is presented. Double‐sided parallel‐strip lines (DSPSLs) are employed to achieve an out‐of‐phase response. Also, an asymmetric dual‐band matching structure with two external isolation resistors is utilized to obtain arbitrary unequal power division, in which the resistors are directly grounded for heat sinking. A through ground via (TGV), connecting the top and bottom sides of the DSPSLs, is used to short the isolation components. Additionally, this property can efficiently improve the broadband matching and isolation bandwidths. To investigate the proposed divider in detail, a set of design equations are derived based on the circuit theory and transmission line theory. The theoretical analysis shows that broadband responses can be obtained as proper frequency ratios are adopted. To verify the proposed concept, a sample divider with a power division of 2:1 is demonstrated. The measured results exhibit a broad bandwidth from 1.19 GHz to 2.19 GHz (59.2%) with a return loss better than 10 dB and port isolation of 18 dB.     

数字可调电位器在自动化测试中的应用研究

为解决机械式可调电阻精度低、易受干扰的问题,利用数字可调电位器设计了电压微调电路,实现了对某装备的自动化测试,有效的提高了测试精度.结合工程实例,介绍了在自动化测试中利用数字可调电位器实现电压微调的具体方法.     

一种多通道温度采集系统的研制

介绍了一种多通道温度采集系统,详细分析了其测量原理及测量误差,给出了其系统设计。本系统采用BA1作为温度传感器,使用AD7792芯片完成温度采集和通道故障检测,简化了电路。在设计中,不仅在硬件上应用了多种新型元器件完成严格的抗干扰措施,在软件上也通过滤波技术、软件陷阱等方法,确保系统的稳定性。经现场调试、运行,温度测量的准确度、精度都达到了设计要求,系统运行良好。     

硅微悬臂梁谐振器的电激电拾方法研究

采用电热激励、压电拾取方法对硅微机械悬臂梁的谐振性能进行了实验研究。成功实现了对硅微悬臂梁谐振器前三阶振型的实验测试。电热激励利用在硅微机械悬臂梁表面优化设计的热激励电阻加以实现。为拾取硅微悬臂梁的微弱谐振信号,在硅微悬臂梁表面优化设计并制作了压敏电阻全桥,利用压敏电阻的压电效应实现对谐振微弱信号的拾取。     

敏感元件在有线电视器件中的应用

阐述敏感元件的基本概念及其在有线电视网络器件中的几种典型应用，首先介绍敏感材料的基本类型和今后的发展趋势，然后详细介绍目前比较典型的几种敏感元件在开关稳压电源、Cable Modem、双向放大器、彩电消磁、程控交换机、光工作站中的应用。     

单片集成电路中镍—铬电阻的制作

本文介绍单片集成电路中采用高精度、高可靠性和低温度系数镍-铬金属薄膜电阻代替扩散电阻的情况,详细论述镍-铬电阻的制作工艺、操作过程及工艺中的注意事项。实验表明,严格控制工艺条件是保证制取优值镍-铬电阻的关键。     

采用数字合成技术的三相正弦波信号发生器

采用数字合成技术制作了三相正弦波信号发生器 ,其波形采用 3个加权电阻网络和高速CMOS开关数字合成 ,精确保证 3个正弦波之间的相位差为 12 0° ,产生的信号具有极好的幅值、稳定的频率、小失真和高达 3.3MHz的宽频率范围     

Accelerated thermal fatigue of lead-free solder joints as a function of reflow cooling rate

Leadless chip resistor (LCR) assemblies were manufactured using both traditional tin-lead (Sn37Pb) and lead-free (Sn3.8Ag0.7Cu) solders. The leadfree test vehicles were assembled using three different cooling rates: 1.6°C/sec, 3.8°C/sec, and 6.8°C/sec. They were then exposed to accelerated thermalcycling (ATC) tests between 0°C and 100°C with a 10–14°C/min ramp rate and a 5-min dwell time. The test results indicated that these lead-free solder joints had better creep-fatigue performance than the tin-lead solder joints. The LCR built with the medium cooling rate showed the longest fatigue life compared with the resistors built with the normal cooling rate of 1.6°C/sec and the higher cooling rate 6.8°C/sec. The number of cycles to failure was significantly correlated to the void defect rate. Failure analyses were done using cross-sectioning methods and scanning electron microscopy (SEM). Finite-element models were built to analyze the inelastic, equivalent strain range in solder joints subjected to thermal-cycling conditions with different degrees of solder wetting. The results indicated that poor wetting increases strains throughout the joint significantly, which is in accordance with the ATC results.