适用于D类音频功放的PWM高速比较器设计

设计了一种应用于CMOS D类音频功率放大器的PWM高速比较器。输入级为Rail-to-Rail结构,中间级由锁存器和自偏置差分放大器组成,输出级为反相器结构。由于采用了锁存器和自偏置放大器结构,比较器可以在很短的时间内驱动大电容,满足后续电路对驱动能力的要求。基于CSMC 0.5μm CMOS工艺的BSIM3V3Spice模型,采用Hspice对PWM比较器进行仿真。结果表明,在典型模型下,比较器的电源抑制比为56dB,直流开环增益为45dB,输入共模范围(ICMR)为-0.19～4.93V,传输延时为15ns。     

一种应用于PWM D类音频功率放大器的CMOS Rail-to-Rail比较器

提出了一种应用于CMOS D类音频功率放大器的Rail-to-Rail PWM比较器,其输入级为Rail-to-Rail结构,输出级为AB类输出。基于CSMC 0.5μm CMOS工艺的BSIM3V3 Spice模型,采用Hspice对PWM比较器的特性进行了仿真,典型模型下的直流开环增益为50dB,电源抑制比为52dB,ICMR为0.04V~4.98V,传输时延为24.5ns,版图有效面积为210×75μm2。由于PWM比较器的良好性能参数,所以其不仅适用于D类音频功率放大器,也能应用于各类低频数据转换电路。     

一种新型高速CMOS全差分运算放大器设计

设计了一种基于流水线模/数转换系统应用的低压高速CMOS全差分运算放大器。该运放采用了折叠式共源共栅放大结构与一种新型连续时间共模反馈电路相结合以达到高速度及较好的稳定性。设计基于SMIC 0.25μm CMOS标准工艺模型,在Cadence环境下对电路进行了Spectre仿真。在2.5V单电源电压下,驱动0.5pF负载时,开环增益为71.1dB,单位增益带宽为303MHz,相位裕度为52°,转换速率高达368.7V/μs,建立时间为12.4ns。     

一种用于流水线结构ADC中改进速度/功耗比的CMOS动态比较器

提出了一种适用于高速、单级低分辨率流水线结构ADC的全差分动态比较器.由于采用了电流源耦合和差分对输入结构,比较器的翻转阈值电压可以设计为任意值.与传统的比较器相比,该比较器较好地兼顾了面积、功耗以及速度等方面,在这些方面有了较大的改进.该比较器在0.35μm CMOS工艺下完成流片,面积为30μm×70μm.仿真和测试结果表明,该比较器可以在2Vpp的输入信号和1GHz的时钟频率下工作,在3.3V的电源电压下,功耗仅为181μW.速度/功耗比达到了5524GS/J.     

一种用于流水线结构ADC中改进速度/功耗比的CMOS动态比较器

提出了一种适用于高速、单级低分辨率流水线结构ADC的全差分动态比较器.由于采用了电流源耦合和差分对输入结构,比较器的翻转阈值电压可以设计为任意值.与传统的比较器相比,该比较器较好地兼顾了面积、功耗以及速度等方面,在这些方面有了较大的改进.该比较器在0.35μm CMOS工艺下完成流片,面积为30μm×70μm.仿真和测试结果表明,该比较器可以在2Vpp的输入信号和1GHz的时钟频率下工作,在3.3V的电源电压下,功耗仅为181μW.速度/功耗比达到了5524GS/J.     

一种高效2.1声道D类音频功放设计

基于CSMC 0.5μm DPDM CMOS工艺,实现了一种具有2.1声道的D类音频功率放大器的设计,该功放由一个全桥差分输出结构的重低音功率放大器和两个半桥单端输出结构的立体声功率放大器构成。详细介绍了2.1声道D类音频功放的整体结构、前置运算放大器和轨至轨比较器的电路设计。仿真和测试结果表明:在电源电压5 V,该功放可向3Ω负载电阻提供2.5 W+0.6 W×2的输出功率;在电源电压3～6 V范围内,最大转换效率可达90%以上;重低音通道的总谐波失真与噪声之和小于0.7%,立体声通道的总谐波失真与噪声之和小于1%。     

D类功放中输入斩波运放电路的设计

基于n阱0.5μm DPDM CMOS工艺,完成了D类音频功放中输入斩波运算放大器的设计.分析了D类系统对输入运放的设计要求,在此基础上确定了电路采用两级全差分结构实现.并加入斩波结构降低噪声.采用PTAT电流源提供运放的偏置电流,补偿运放跨导gm的温度漂移.在Cadence下的电路仿真表明,前级运放具有16 μV·Hz-1/2的等效输入噪声,开环增益达到117.3 dB.运放所在芯片经过PWM方式流片验证,测试结果显示,芯片THD达到0.58%(f=1 kHz、P.=1 W、VDD=5 V),电源抑制比为65 dB.     

一种BTL低静态功耗CMOS音频功率放大器的设计

对AB类CMOS音频功率放大系统中的核心运放单元电路结构,即基于共漏与共源并联组合的功率级放大电路进行了改进与优化设计a基于CSMC0.6 μm CMOS工艺的仿真结果表明,在5 V电源电压下,静态电流仅为1.59 mA.BTL模式驱动4 Ω的负载,当1 kHz频率点的总谐波失真小于0.1%时,获得的最大输出功率可以达到2 W,电源转换效率为60.7%.     

一种适用于IEEE802．15．4（ZigBee）标准的2．4GHz CMOS射频收发机设计

本文提出了一种适用于IEEE 802．15．4标准的2.4GHz免认证ISM频段的全集成CMOS射频收发机．接收机采用低中频结构以降低功耗、提高灵敏度,发射机则采用直接上变频结构以降低设计复杂度和功耗．芯片采用0.18μm 1P4M CMOS工艺以及MIM电容制造,供电电压1.8V ．测试结果显示,在误包率为1％时,接收机灵敏度达到了-97dBm ,发射机输出至100Ω差分天线端口的最大输出功率为＋3dBm ．接收模式和发射模式下的电流功耗分别为17mA和19mA ,芯片面积3.3mm ×2.8mm ．     

一种用于SAR ADC开关电容比较器的失调消除技术

论文阐述了一种用于逐次逼近ADC开关电容比较器的失调消除技术。采用预放大加再生锁存的比较结构,基于0.18μm 1P5M CMOS工艺设计实现了一种伪差分比较器。通过采用前级预放大器输入失调消除技术以及低失调再生锁存技术进行设计,整个比较器的输入失调电压小于0.55mV。通过采用预放大加再生锁存的比较模式,整个比较器的功耗有效减小,不足0.09mW。在电源电压为1.8V、ADC采样速率为200kS/s、时钟频率为3MHz的情况下,比较器能达到13位的转换精度。最后,通过设计讨论、后仿真分析及其在一种10位200kS/s的触摸屏SAR ADC中的成功应用验证了本文比较器的实用性和优越性。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.