An Ultra Low Power Non-volatile Memory in Standard CMOS Process for Passive RFID Tags

An ultra low power non-volatile memory is designed in a standard CMOS process for passive RFID tags. The memory can operate in a new low power operating scheme under a wide supply voltage and clock frequency range. In the charge pump circuit the threshold voltage effect of the switch transistor is almost eliminated and the pumping efficiency of the circuit is improved. An ultra low power 192-bit memory with a register array is implemented in a 0.18 mu M standard CMOS process. The measured results indicate that, for the supply voltage of 1.2 volts and the clock frequency of 780KHz, the current consumption of the memory is 1.8 mu A (3.6 mu A) at the read (write) rate of 1.3Mb/s (0.8Kb/s).

Comparative study of the surface passivation on crystalline silicon by silicon thin films with different structures

Si thin films with different structures were deposited by plasma enhanced chemical vapor deposition (PECVD), and characterized via Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The passivation effect of such different Si thin films on crystalline Si surface was investigated by minority carrier lifetime measurement via a method, called microwave photoconductive decay (mu PCD), for the application in HIT (heterojunction with intrinsic thin-layer) solar cells. The results show that amorphous silicon (a-Si:H) has a better passivation effect due to its relative higher H content, compared with microcrystalline (mu c-Si) silicon and nanocrystalline silicon (nc-Si). Further, it was found that H atoms in the form of Si-H bonds are more preferred than those in the form of Si-H-2 bonds to passivate the crystalline Si surface. (C) 2009 Elsevier B.V. All rights reserved.

三层交换机中DHCP中继代理的改进与实现

社区宽带综合业务网络系统使用交换式以太网技术。为社区用户提供Intemet接入、电视、IP电话等服务。根据系统的实际需求，提出了一种改进的DHCP中继代理机制，并将该机制在系统的核心三层交换机SW1200的驱动程序中实现。

一种多业务以太网接入交换机的关键技术

宽带社区接入网是下一代网络研究的主要领域之一.RBISN(社区宽带综合业务网络系统)研究使用交换式以太网提供数字电视、IP电话和Internet接入服务.需要解决用户隔离、组播、服务质量的问题.本文介绍了这一系统中交换机采用的关键技术.

一种多业务宽带接入交换机的设计与实现

在接入网中提供多业务可以有效地降低运营维护成本和网络铺设费用,同时提高网络利用率.采用组播技术和具有多项服务质量(QoS)选择的多层以太网交换机,可以实现能提供QoS保证的多业务宽带接入网.该文介绍了一种多业务宽带接入交换机的设计与实现,按功能模块分述并讨论了其中的难点和要点.

交换机和路由器一体化的设计与实现

宽带社区接入网是下一代网络研究的主要领域之一.RBISN(社区宽带综合业务网络)研究使用交换式以太网提供电视、IP电话和Internet接入服务,边缘路由设备必不可少.该文分析了该环境下的通信量,在对可用的方案进行对比的基础上,提出了将智能二层VLAN交换机和VLAN路由器一体化的方案.随后给出其模型和设计,加以实现以证明其可行性.

Characteristic of the ultrawideband electromagnetic radiation generated by PCSS

A novel ultra-wideband electromagnetic pulse generating method based on the photoconductive semiconductor switches (PCSS) is presented. Gallium arsenide is used to develop the PCSS for an ultrashort electromagnetic pulse source. The pulse generated by such PCSS is within picosecond (ps) time scale, and can yield power pulse with an voltage over 10 kV. The experimental results show that the pulses are stable, with the peak-peak amplitude change of 6% and the time jitter within several picoseconds. The radiations of the PCSS triggered by the picosecond laser and fenitosecond laser pulse series illustrate that the electromagnetic pulses would have high repetition of more than 80 MHz and frequency bandwidth of DC-6 GHz. The radiations of "lock-on " mode of the PCSS are also analyzed here. (c) 2007 Wiley Periodicals, Inc.

Kinetics of picosecond laser pulse induced charge separation and proton transfer in bacteriorhodopsin

Bacteriorhodopsin (BR) films oriented by an electrophoretic method are deposited on a transparent conductive ITO glass. A counterelectrode of copper and gelose gel is used to compose a sandwich-type photodetector with the structure of ITO/BR film/gelose gel/Cu. A single 30-ps laser pulse and a mode-locked pulse train are respectively used to excite the BR photodetector. The ultrafast failing edge and the bipolar response signal are measured by the digital oscilloscope under seven different time ranges. Marquardt nonlinear least squares fitting is used to fit all the experimental data and a good fitting equation is found to describe the kinetic process of the photoelectric signal. Data fitting resolves six exponential components that can be assigned to a seven-step BR photocycle model: BR-->K-->KL-->L-->M-->N-->O-->BR. Comparing tests of the BR photodetector with a 100-ps Si PIN photodiode demonstrates that this type of BIR photocletector has at least 100-ps response time and can also serve as a fast photoelectric switch. (C) 2003 Society of Photo-Optical Instrumentation Engineers.

Spectrum broadening and reshaping via gain compensation of fiber amplifier

We report a novel technique to broaden and reshape the spectrum of picosecond laser pulse based on the seeder of gain switch laser diode and Yb(3+)-doped fiber amplifier (YDFA). From compensating the seed spectrum with the gain of YDFA, the seed pulse of 7 nm bandwidth is broadened to 20 nm, and the flat top spectral shape is obtained as well. A self-made fiber coupled tunable filter is used to realize the tunable output laser with the wavelength range from 1053 nm to 1073 nm and the line width of 1.4 nm.

Current oscillations and stable electric field domains in doped GaAs/AlAs superlattices

The crossover between two regimes has been observed in the vertical electric transport of weakly coupled GaAs/AlAs superlattices (SLs). At fixed d.c. bias, the SLs can be triggered by illumination to switch from a regime of temporal current oscillation to the formation of a stable electric field domain. The conversion can be reversed by raising the sample temperature to about 200 K. An effective carrier injection model is proposed to explain the conversion processes, taking into account the contact resistance originating from DX centres in the n(+)-Al0.5Ga0.5As contact layers which is sensitive to light illumination and temperature. In addition, quasiperiodic oscillations have been observed at a particular d.c. bias voltage.