应用于神经信号再生系统的跨导放大器

采用华润上华0.6μm标准CMOS混合信号工艺设计了一种应用于植入式神经信号再生系统的跨导放大器.该放大器采用全差分结构以获得高输出摆幅,利用源反馈技术改善线性度,并设计了共模反馈电路以稳定共模输出电压.该跨导放大器工作在5V的电源电压下,具有0.55 S的跨导增益和100 kHz的3 dB带宽,可以满足系统的需要.     

基于单一PMOS差分对的轨到轨输入运算放大器设计

基于国内某CMOS工艺设计了一种单一PMOS差分对的轨到轨输入、恒跨导CMOS运算放大器。输入级电路采用折叠共源共栅结构,通过体效应动态调节输入管的阈值电压扩展共模输入范围到正负电源轨,恒定共模输入范围内的跨导,自级联电流镜有源负载将差分输入转换为单端输出;输出级电路采用AB类结构实现轨到轨输出,线性跨导环确定输出管的静态偏置电流。在5 V电源电压,2.5 V共模电压,1 MΩ负载条件下,经Spectre仿真验证,该运算放大器开环增益为119 dB,相位裕度为58°,共模输入范围为0.0027～4.995 V,共模范围内跨导变化小于3%,实现了轨到轨输入共模范围内的跨导恒定。     

用于脑电信号记录的低噪声低功耗放大器

为了满足脑电信号(EEG)记录阵列的应用需求,设计了一种全差分的低噪声、低功耗放大器电路.该电路利用亚阈值区晶体管作为伪电阻,与输入电容和反馈电容形成高通通路,有效抑制了输入信号的直流失调电压,无需片外隔直电容,实现了电路的全集成.放大器中的跨导放大器(OTA)采用亚阈值晶体管进行设计,实现了较大的输出摆幅、良好的功耗和噪声性能.放大器电路采用SMIC 130 nm 1P8M混合信号工艺实现,芯片面积0.6 mm2.测试结果表明,在电源电压0.6V时,放大器可处理信号带宽为10 Hz～7 kHz,等效输入噪声的均方根值为3.976 μV,噪声有效因子为3.658,总功耗仅为2.4 μW.     

一款基于电荷泵高压内电源的恒定跨导轨到轨运算放大器

设计了一款基于电荷泵高压内电源的恒定跨导轨到轨运算放大器.输入级采用PMOS差分对结构,通过电荷泵产生高于电源电压的输入级内电源,使运放在轨到轨输入范围能正常工作并保持输入跨导恒定.电荷泵电路所需的时钟信号通过内部振荡器电路产生,再通过电压自举电路和时序电路产生所需电平的非交叠开关控制信号,最后利用时间交织结构输出连续稳定的高压内电源.在电荷泵实现中还采用了辅助开关结合跟随运放的结构降低了主开关在切换时的毛刺.该运放在折叠式共源共栅结构中使用增益自举结构提高了总体增益,输出级采用class AB类输出结构实现轨到轨输出.该运算放大器基于0.5μm CMOS工艺完成电路与版图设计,仿真结果表明,在5 V电源电压下,直流增益为150.76 dB,单位增益带宽为53.407 MHz,相位裕度为96.1°,输入级跨导在轨到轨输入共模范围内的变化率为0.001 25%.     

一种基于降压DC-DC转换器的高性能误差放大器设计

基于降压型DC-DC转换器的工作原理,从系统需要出发,提出一种高性能的误差放大器。该误差放大器的输入级采用偏置电流消除结构,避免其输入对基准电压产生影响;核心电路采用对称性的差分运放结构,引入正反馈结构和负反馈电阻以提高其性能,电路结构采用CSMC 0.5μm BCD工艺。仿真结果表明该误差放大器跨导为1.5 mS,共模下限可以从0开始,共模抑制比为106 dB,失调电压为208.3μV,功耗约为100μW,验证了该放大器的良好性能。     

低功耗恒定跨导轨对轨运算放大器设计技术研究

为了解决轨对轨运算放大器输入级跨导随共模输入电压变化的影响,采用实时共模电压监测技术,动态跟踪轨对轨运放输入级的跨导变化,通过对偏置电流的高精度定量补偿,从而实现了对输入级跨导的恒定性控制。基于0.18μm CMOS工艺进行了具体电路的设计实现,结果表明:在电源电压3.3 V、负载电阻100Ω、负载电容1 nF的条件下,运放增益为148 dB、相位裕度为61°、功耗为39.6μW,共模输入范围高达0~3.3 V,输入级跨导变化率仅为2.1%。     

宽输入共模范围电压比较器的设计

当输入信号的共模值超过或者接近电源电压时,传统的电压比较器就会出现不足,因此有必要设计新的比较器来实现对高共模信号的检测.采用了共栅差分输入级,极大地增加了输入共模信号的范围.基于此输入级设计了两个电压比较器,一个在锂电池充电电路中实现了对电池和电源电压的监控,另一个响应速度快.CSMC 0.6 μm CMOS工艺的仿真结果表明,前者能简便的实现输入失调和迟滞控制功能,静态电流仅为1.2 μA;后者在单电源5 V下输入共模范围是1.3～15 V,在10 mV的过驱动电压下,延时为11 ns,静态工作电流为91 μA.     

全摆幅运算放大器的设计

设计了一种全摆幅输入的运算放大器。通过恒定跨导结构实现互补输入差分对共模输入电压在轨到轨范围内对恒定跨导的控制。设计中在输出结构里使用了电流求和电路,以达到输出信号相加,实现单端输出的功能。采用Spectre进行仿真,电源电压5V时,低频增益84dB,单位增益带宽12MHz。     

一种高共模抑制比恒定跨导运算放大器

介绍了一种基于电平位移技术实现恒定跨导的CMOS Rail-to-Rail运算放大器。该电路克服了一般运算放大器输入共模范围小的特点,输入级引入了电平位移电路,使运放在各种输入共模电压下的跨导几乎恒定。在此基础上,设计了一种具有高共模抑制比的恒定跨导运算放大器。该运算放大器具有Rail-to-Rail的输入、输出能力。整个电路采用Hynix 0.5μm CMOS工艺进行设计。     

一种基于0.6μm BCD工艺的40V高压输出自稳零运算放大器北大核心

设计实现了一种基于0.6μm BCD工艺的40 V高压输出自稳零运算放大器。该运算放大器采用了时间交织自稳零结构，实现了对输入失调电压的连续校准，同时使用40 V耐压PDMOS管和NDMOS管，实现了ClassAB结构的高压输出。运算放大器的输入级和自稳零校准电路采用0.6μm普通MOS管实现，均工作在5 V电源电压下；放大级和输出级中部分晶体管采用非对称结构的40 V DMOS管，实现了高压输出。整体电路中只有DMOS管的漏源电压承受40 V的耐压，其余MOS管的各端电压均在正常的工作范围内，没有耐压超限风险。前仿真结果表明，该运算放大器在5 V和40 V双电源电压下工作正常，输入失调电压为0.78μV,输出电压范围为3.0～37.7 V,等效直流增益为142.7 dB,单位增益带宽为1.9 MHz,共模抑制比为154.8 dB,40 V电源抑制比为152.3 dB,5 V电源抑制比为134.9 dB。     

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.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

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.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.