应用于WSN的0.5 V 4.8 GHz CMOS LC VCO设计

为设计一个可应用于无线传感网的0.5 V 4.8 GHz CMOS LC压控振荡器,采用传统差分负阻结构的电感电容VCO核心电路,添加开关电容阵列增大VCO的调谐范围,利用升压电路和反相器的组合提高控制信号产生电路的性能,通过调节负阻管的宽长比等方法来优化VCO的相位噪声性能,保证VCO能在0.5 V的低供电电压下稳定工作,相位噪声达到-119.3 dBc/Hz@1 MHz,VCO的频率调谐范围为4.3~5.3 GHz,相位噪声小于-115 dBc/Hz@1 MHz,最低可达-121.2 dBc/Hz@1 MHz,核心电路电流约为2.6 mA,满足无线传感网的应用要求。     

光纤接入网技术及展望

光纤接入技术是近几年才被大家所熟识的一项互联网接入技术,因其简捷、高效等特点被业界人士所看好,已作为宽带接入的长远方案。本文简单介绍了光纤接入网的基本原理和技术发展,介绍并阐述了有源光网络与无源光网络的原理和实现,并根据两种光网络组成不同,对两种光网络的几种典型的接入模式进行了较为具体的研究,探讨了光纤接入网建设的基本思路。     

基于UCC28070的交错式PFC设计

利用UCC28070采用Boost拓扑结构,设计了一款功率为1500W的交错式PFC电源.明显改善乘法器设计,为两个独立的电流放大器提供共享的电流参考,保证匹配的平均电流控制PWM输出模式中同时保持一个稳定、低失真的正弦输入电流.可编程工作频率从30kHz到300kHz,有较好的效率和多种保护功能.与传统控制模式相比,增强了PF、效率、总谐波失真等性能.     

有源电力滤波器电流环无静差控制策略研究

本文对传统的电流环复合控制器的检测误差进行了理论分析,指出了检测负载侧电流的局限性,设计了基于传统PI控制和指定谐波指令相结合的电流控制器。该控制器基本上可以做到谐波指令的无静差跟踪,具有良好的补偿性能,克服了传统检测负载侧谐波电流时PI控制器的缺陷,而且具有传统检测负载侧谐波电流的灵活性。即使负载谐波电流高于有源电力滤波器的容量,该控制策略也能够总体上无静差输出,具有一定的理论意义和工程应用价值,理论分析和仿真验证了此种新型控制策略的正确性和有效性。     

环境噪声抑制的红外接近传感器设计

分析红外接近传感器的工作原理,针对红外接近传感器容易受到环境噪声影响而发生检测错误的问题,提出一种高效的环境噪声抑制方法．该方法通过光学镀膜滤波和基于时序控制的数字模拟混合减法电路,分步滤除环境噪声,达到准确接近检测目标的目的．设计了相关传感器电路,可以在太阳光或灯光光照度低于4000lx,温度低于85℃的环境下,实现25cm范围内的物体接近程度的准确测定．在相同工艺下,通过Spec-tre进行仿真,结果表明：该传感器在给定的噪声环境中工作与无环境噪声的理想情况相比,最大误差不超过1％．所设计电路已在0．35μm3VCMOS工艺下投片验证,结果满足设计指标．     

CPT系统拾取端能量注入式稳压电路的设计

针对非接触电能传输系统的输出电压控制方式,分析了影响CPT系统输出电压稳定性的因素,设计了一种能量注入式的拾取端稳压电路.该电路以输出电压为控制对象,以输出功率为控制目标,根据负载的需求实现系统输出电压的稳定,并且在能量状态转换的过程中基本实现了软开关.从能量的角度对该电路的输出电压和输出能量状态进行了分析,根据能量状态的改变提出了功率调节占空比的概念,并给出了相应的计算公式.实验结果证明了该方法的有效性.     

Sound absorption characteristics of a thin plate with PZT and shunt circuit I. Theoretical analysis

The feasibility of sound absorbing by a vibrating plate with piezoelectric material and shunt circuits is theoretically investigated. Based on an equivalent compliance of a piezoelectric wafer shunted with RL circuits, the governing equations for the fiexural vibration of the plate with the piezoelectric wafer are derived using Lagrange＇s approach. The equations take into account not only the mass, stiffness and structural damping of the plate and the wafer, but also the electrical resistance and electrical inductance of the RL circuits. By using the governing equations derived, the surface impedance and sound absorption coefficient of the plate backed with a cavity are given. Numerical results show that the sound absorption coefficient of the plate near its first mode can be significantly improved by adjusting the RL parameters.     

Improved Programming Efficiency through Additional Boron Implantation at the Active Area Edge in 90nm Localized Charge-Trapping Non-volatile Memory

As the scaling-down of non-volatile memory （NVM） cells continues, the impact of shallow trench isolation （STI） on NVM cells becomes more severe. It has been observed in the 90nm localized charge-trapping non-volatile memory （NROMTM） that the programming efficiency of edge cells adjacent to STI is remarkably lower than that of other cells when channel hot electron injection is applied. Boron segregation is found to be mainly responsible for the low programming efficiency of edge cells. Meanwhile, an additional boron implantation of 10°tilt at the active area edge as a new solution to solve this problem is developed.     

Spiking Behavior in Chua's Circuit

Chua ＇s circuit with a slow-fast effect is established under certain parameter conditions. The dynamics of this slow- fast system is investigated. A spiking phenomenon can be observed in the numerical simulation. By introducing slow-fast analysis and a generalized Jacobian matrix at the non-smooth boundaries, the bifurcation mechanism for the periodic spiking solution, different from the smooth case, is discussed.     

High Power Continuous-Wave Actively Mode-Locked Diode-Pumped Nd:YAG Laser

We demonstrate a diode-pumped cw mode-locked Nd：YAG by an acousto-optic mode locker. A mode-locked pulse with duration of 345 ps and output power of 12 W is obtained. The resonator design shows three advantages： a larger mode volume, high stability against thermal lens fluctuations, and excellent beam quality with TE00 mode. Different from previous active mode locking designs, we employ a frequency stabilizer and a phase-lock loop circuit to ensure the mode locking stable operation.