采用电荷复位技术的像素级ADC

实现了一种可用于CMOS图像传感器,采样率为50 Hz、精度为15位的像素级模数转换器(ADC)。此ADC采用电荷复位方式补偿电荷,然后通过对电荷包计数实现模数转换。为了实现低功耗、低噪声和小面积,对电路系统、核心模块的设计以及版图布局布线进行了综合考虑和优化。该设计采用SMIC 0.18μm CMOS标准工艺,版图面积为50μm×50μm。测试结果表明:当输入电流为17.5,33.7和80 nA时,对应的输出码的均值/标准差分别为8 875/6.56,16 500/2.6,32 768/14.3。在满量程输入电流(80 nA)情况下,仿真总功耗仅为4.5μW。     

面向WSN结点SoC的逐次逼近模数转换器

设计了一种适合于无线传感网(WSN)结点SoC芯片传感器接口电路应用的12 bit精度逐次逼近型(SAR)模数转换器(ADC)。为了实现高精度、低成本,并兼容射频CMOS工艺的要求,利用全差分结构和带有Auto-zero失调消除功能的比较器提高转换精度。采用分段式电容阵列DAC减小芯片占用面积,通过构造符合精度要求的MOM电容单元,使电容阵列符合射频CMOS的工艺特点,利于嵌入式应用。同时,采取增加辅助电容的办法扩大输入信号范围。该ADC在0.18μm 1P6M标准CMOS工艺下实现,版图面积为0.9 mm2,最高采样速率为1 MS/s,在1.8 V电源电压下,整体功耗仅为2 mW。     

无源温度标签中的超低功耗CMOS温度传感器设计

设计了一种适用于无源超高频(UHF)温度标签的超低功耗CMOS温度传感器电路.该电路利用衬底pnp晶体管产生随温度变化的电压信号,同时采用了逐次逼近寄存器(SAR)转换和∑-△调制相结合的模拟数字转换方式.为了降低电源电压波动以及采样电容电荷泄漏对传感器测温精度的不利影响,提出了一种具有漏电保护机制的采样电路.基于0.18 μm CMOS工艺设计实现了该传感器的电路和版图,其中版图面积为550 μm×450 μm,并利用Cadence Spectre仿真工具对电路进行了仿真.仿真结果表明,在-40～ 125℃,传感器的系统误差为-1.4～2.0℃,测温分辨率达到0.02℃;在1.2～2.6 V电源电压内,传感器输出温度波动小于0.3℃;在1.2V电源电压下传感器电路(不合控制逻辑及数字滤波器)的功耗仅为2.4μW.     

超低功耗逐次逼近寄存器型模数转换器的设计

采用逐次逼近方式设计了一个12 bit的超低功耗模数转换器(ADC).为减小整个ADC的芯片面积、功耗和误差,提高有效位数(ENOB),在整个ADC的设计过程中采用了一种改进的分段电容数模转换器(DAC)阵列结构.重点考虑了同步时序产生电路结构,对以上两个模块的版图设计进行了精细的布局.采用0.18 μm CMOS工艺,该ADC的信噪比(SNR)为72 dB,有效位数(ENOB)为11.7 bit,该ADC的芯片面积只有0.36 mm2,典型的功耗仅为40 μW,微分非线性误差小到0.6 LSB、积分非线性误差只有0.63 LSB.整个ADC性能达到设计要求.     

一种应用于CMOS图像传感器的列级高精度ADC设计

针对CMOS图像传感器高精度和低功耗的需求,设计了一种14位列级模数转换器(ADC)。在传统斜坡式模数转换器(RAMP ADC)架构基础上,采用了3位逐次逼近型模数转换器(SAR ADC)与11位RAMP ADC相结合的两步式结构,有效缩短了量化时间。RAMP ADC部分采用高低时钟的计数方法,可显著降低计数区间内的功耗。同时,提出了RAMP-SAR-RAMP切换的相关双采样逻辑,可进一步减少静态随机存取存储器(SRAM)数量,从而缩小版图面积。采用0.18μm标准CMOS工艺进行仿真,结果表明:在600 MHz时钟、单沿计数的工作模式下,ADC量化时间为9.32μs,在1.8 V数字电源电压下,计数区间内功耗均值为8.51μW。     

一种实时CIS暗电流校正方法及系统实现

为了减弱暗电流对互补型金属氧化物半导体(CMOS)图像传感器(简称CIS)图像质量的影响,本文基于图像处理的方式提出了一种实时校正CMOS图像传感器暗电流的方法,并在一个最高帧频(50f/s)的4晶体管像素结构CMOS图像传感器内集成了该方法的电路。测试结果表明,该方法获得了准确的暗电平,并且实时消除了75%以上暗电流引入的固定模式噪声(FPN,fixed pat-tern noise),大大改善了图像质量。     

一种适用于传感器接口电路中电容型SAR结构ADC的修调技术

本文提出了一种针对电容型逐次逼近型模数转换器（ADC）的修调技术及实现算法,采用了该技术的ADC可作为传感器和微控制器之间的接口电路使用。其特点在于这种修调后的电路可以在不需要单独的校正周期,也不需要附加复杂的校正功能,只需要通过对电容阵列的微调,就可以达到12-bit的分辨率。这种技术具有功耗和面积的优势,适合用于对功耗和成本较为敏感的电池供电系统,例如传感器网络结点。本文在0.5μm 2P3M CMOS工艺下设计了一个12bit分辨率的ADC原型电路,在2-5V电源电压下,200KHz采样速度下,其功耗仅为300μA。     

一种具有纹波消除技术的10 bit SAR ADC

逐次逼近寄存器模数转换器(SAR ADC)在逐次逼近的过程中,电容的切换会使参考电压上出现参考纹波噪声,该噪声会影响比较器的判定,进而输出错误的比较结果。针对该问题,基于CMOS 0.5μm工艺,设计了一种具有纹波消除技术的10 bit SAR ADC。通过增加纹波至比较器输入端的额外路径,将参考纹波满摆幅输入至比较器中;同时设计了消除数模转换器(DAC)模块,对参考纹波进行采样和输入,通过反转纹波噪声的极性,消除参考纹波对ADC输出的影响。该设计将信噪比(SNR)提高到56.75 dB,将有效位数(ENOB)提升到9.14 bit,将积分非线性(INL)从-1～5 LSB降低到-0.2～0.3 LSB,将微分非线性(DNL)从-3～4 LSB降低到-0.5～0.5 LSB。     

一种不同缩放类型组合的低功耗DAC

提出了一种内置于SAR ADC的低功耗DAC,采用不同缩放类型分段组合的方式,明显减小了芯片占用面积,降低了功耗。基于华润上华公司的0.35 μm CMOS工艺,利用Cadence Spectre仿真工具对电路进行分析,结果显示该DAC整体电路的功耗为0.93 mW,最大积分非线性(INL)为－0.74 LSB,最大微分非线性(DNL)为－0.48 LSB,优值(FOM)为3.81,版图的面积为0.086 mm²,很好地满足了低功耗和小面积的要求。     

一种接触式图像传感器非均匀性实时校正方法

提出了一种接触式图像传感器(CIS)非均匀性的校正方法,能够快速高效地对CIS图像的非均匀性进行校正,消除其不一致性,提高了图像质量.该方法采用改进的分区两点法进行校正,分为标定和校正2个过程.标定过程获取CIS中各个光敏单元的校正系数和灰度偏移量,校正过程利用标定值对CIS的输出进行校正和补偿,最终得到均匀的CIS图像.校正过程利用现场可编程门阵列(FPGA)实现,在图像传输的过程中同时进行,每次采集的校正延时不到0.5μs,具有极强的实时性.     

聚对苯撑苯并双(口恶)唑发光及其器件制备

采用光谱技术,研究了聚对苯撑苯并双(口恶)唑(PBO)溶液的光敏发光特性,并用相对法估算出溶液发光效率在50%范围.结合光谱技术、半导体电学和电化学等研究手段,具体研究了以PBO为发光层的单层电致发光器件,研究结果显示,电致发光与薄膜的光致发光有具有相同的发光中心,峰值位于510 nm左右.同时发现,由于存制备过程中不同处理条件使得不同厚度薄膜残留的掺杂物质浓度不同,从而引起薄膜的导电性的不同.使得器件的阈值场强随PBO厚度的减小而逐渐增加.     

系统级封装新型埋入式电源滤波结构的研究

在高密度小尺寸的系统级封装(SiP)中,对供电系统的完整性要求越来越高,多芯片共用一个电源网路所产生的电压抖动除了会影响到芯片的正常工作,还会通过供电网路干扰到临近电路和其他敏感电路,导致芯片误动作,以及信号完整性和其他电磁干扰问题.这种电压抖动所占频带相当宽,几百MHz到几个GHz的中频电源噪声普通方法很难去除.结合埋入式电容和电源分割方法的特点,提出一种新型高性能埋入式电源低通滤波结构直接替代电源/地平面.研究表明,在0.65～4GHz的频带内隔离深度可达-40～75 dB,电源阻抗均在0.25ohm以下,实现了宽频高隔离度的高性能滤波作用.分别用电磁场和广义传输线两种仿真器模拟,高频等效电路模型分析这种低通滤波器的工作原理以及结构对隔离性能的影响,并进行了实验验证.     

Emerging interconnects: a state-of-the-art review and emerging solutions

Aluminium was a primary material for interconnection in integrated circuits (ICs) since their inception. Later, copper was introduced as interconnect material which has better metallic conductivity and resistance to electromigration. As the aggressive technology scaling continues, the copper resistivity increased because of size effects, which causes increase in delay, power dissipation and electromigration. The need to reduce the resistor-capacitor??????? delay, dynamic power utilisation and the crosstalk commotion is as of now the fundamental main impetus behind the presentation of new materials. The purpose of this paper is to do a survey of interconnect material used in IC from introduction of ICs to till date. This paper studies and reviews new materials available for interconnect application which are optical interconnects, carbon nanotube (CNT), graphene nanoribbons (GNRs) and silicon nanowires which are alternatives to copper. While doing a survey of interconnect material, it is found that multiwalled CNTs, multilayer GNR and mixed CNT bundles are promising candidates and are ultimate choice that can strongly address the problems faced by copper but on integration basis copper would last for coming years.     

Arsenic deposition as a precursor layer on silicon (211) and (311) surfaces

We investigate the properties of arsenic (As) covered Si(211) and Si(311) surfaces by analyzing data from x-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED) images. We then create a model using total surface energy calculations. It was found that both Si(211) and Si(311) had 0.68±0.08 surface As coverage. Si(211) had 0.28±0.04 Te coverage and Si(311) had 0.24±0.04 Te coverage. The Si(211) surface replaces the terrace and trench Si atoms with As for a lower surface energy, while the Si edge atoms form dimers. The Si(311) surface replaces all terrace atoms and adsorbs an As dimer every other edge site. These configurations imply an improvement in the mean migration path from the bare silicon surface by allowing the impinging atoms for the next epitaxial layer, tellurium (Te), to bind at every other pair of edge atoms, and not the step terrace sites. This would ensure a nonpolar, B-face growth.     

光子晶体微腔发光二极管

光子晶体微腔因其具有增强自发辐射、定向输出和单模工作的能力而受到广泛关注。介绍了光子晶体微腔发光二极管的基本原理、设计、特性、制作及其典型器件。     

Comparative study of maximum power point tracking techniques for hybrid renewable energy system

The power generation demand is increasing day-by-day throughout the world, therefore, the use of hybrid systems becomes a significant solution. The hybrid renewable energy system (HRES) is used for delivering power in various regions in order to overcome intermittence of wind and solar resources. Because of increasing environmental problems, for example, greenhouse gas emission and energy cost have interested novel research into substitute methods in favour of electrical power generation. Maximum Power Point Tracking (MPPT) control method is a vast deal of novel research used for enhancing the efficiency of HRES. The authors have revealed that the hybrid techniques i.e. Global MPPT, fuzzy-neuro systems, Adaptive Neuro-Fuzzy Inference System (ANFIS), Perturbed and Observe (P&O) + Adaptive Neural Network (ANN) etc. can provide best results as compared to other MPPT control methods. This paper offering a state of art review of MPPT control techniques for HRES.     

用于单光子TOF测量的时间-幅度变换器

基于新型共源共栅电流源的积分方法,设计了一种用于单光子飞行时间(TOF)测量的时间-幅度变换器(TAC)。该方法有效简化了TAC电路结构,减小了TAC占用面积,显著提高了TOF的满量程范围(FSR)。采用0.18 μm标准CMOS工艺设计。集成TAC的单光子探测器像素单元的填充因子可达到26.8%。后仿真结果表明,该TAC在120 ns的FSR内具有230 ps的定时分辨率,微分非线性(DNL)低于0.05 LSB,积分非线性(INL)低于1.1 LSB。蒙特卡洛仿真表明,512个TAC像素间的不均匀性低于0.5 %。该TAC非常适用于高密度时间相关的单光子计数(TCSPC)探测器阵列。     

Joint estimation of TOA and DOA in IR-UWB system using a successive propagator method

Impulse radio ultra-wideband (IR-UWB) ranging and positioning require accurate estimation of time-of-arrival (TOA) and direction-of-arrival (DOA). With receiver of two antennas, both of the TOA and DOA parameters can be estimated via two-dimensional (2D) propagator method (PM), in which the 2D spectral peak searching, however, renders much higher computational complexity. This paper proposes a successive PM algorithm for joint TOA and DOA estimation in IR-UWB system to avoid 2D spectral peak searching. The proposed algorithm firstly gets the initial TOA estimates in the two antennas from the propagation matrix, then utilises successively one-dimensional (1D) local searches to achieve the estimation of TOAs in the two antennas, and finally obtains the DOA estimates via the difference in the TOAs between the two antennas. The proposed algorithm, which only requires 1D local searches, can avoid the high computational cost in 2D-PM algorithm. Furthermore, the proposed algorithm can obtain automatically paired parameters and has better joint TOA and DOA estimation performance than conventional PM algorithm, estimation of signal parameters via rotational invariance techniques algorithm and matrix pencil algorithm. Meanwhile, it has very close parameter estimation to that of 2D-PM algorithm. We have also derived the mean square error of TOA and DOA estimation of the proposed algorithm and the Cramer-Rao bound of TOA and DOA estimation in this paper. The simulation results verify the usefulness of the proposed algorithm.     

超宽带脉冲信号的光学生成方法研究

近年来超宽带(UWB)通信技术迅猛发展,在测量、雷达技术、民用和军事无线通信中有着重要的应用,UWB-over-fiber技术已经成为目前研究的热点,其中就包括UWB脉冲信号的产生方法。区别于传统的电子学方法,光子学产生方法不受电子瓶颈制约,可以实现很高的带宽,并且具有抗电磁干扰、重量轻、结构紧凑的优点。通过对比国内外本领域研究成果,讨论及总结了以下三种原理的UWB脉冲信号的光学生成方法:1)相位调制-强度调制转换(PM-IM);2)半导体光放大器(SOA)的非线性效应;3)频谱塑形和色散所致频域-时域映射,然后对各种方案进行了对比分析。     

多孔硅发光机制的分析

从量子力学的基本理论出发讨论了量子限制效应，推导出多孔硅有效禁带宽度增量并用量子限制效应和表面态及其物质在发光中作用的理论解释了ＰＳ光致发光的实验现象。