VLSI scaling methods and low power CMOS buffer circuit

Device scaling is an important part of the very large scale integration(VLSI) design to boost up the success path of VLSI industry, which results in denser and faster integration of the devices. As technology node moves towards the very deep submicron region, leakage current and circuit reliability become the key issues. Both are increasing with the new technology generation and affecting the performance of the overall logic circuit. The VLSI designers must keep the balance in power dissipation and the circuit’s performance with scaling of the devices. In this paper, different scaling methods are studied first. These scaling methods are used to identify the effects of those scaling methods on the power dissipation and propagation delay of the CMOS buffer circuit. For mitigating the power dissipation in scaled devices, we have proposed a reliable leakage reduction low power transmission gate(LPTG) approach and tested it on complementary metal oxide semiconductor(CMOS) buffer circuit. All simulation results are taken on HSPICE tool with Berkeley predictive technology model(BPTM) BSIM4 bulk CMOS files. The LPTG CMOS buffer reduces 95.16% power dissipation with 84.20% improvement in figure of merit at 32 nm technology node. Various process, voltage and temperature variations are analyzed for proving the robustness of the proposed approach. Leakage current uncertainty decreases from 0.91 to 0.43 in the CMOS buffer circuit that causes large circuit reliability.     

适用于光电跟踪仪的高速目标跟踪控制算法

为了提高光电跟踪仪对于高速运动目标的跟踪精度和稳定性,提出一种适用于光电跟踪仪的高速目标跟踪控制算法。利用光电跟踪仪、火炮、载体惯导系统、视频跟踪器和激光测距机输出的相关参数,通过一系列坐标转换、递推迭代和坐标反变换,完成瞄准线坐标系下方位速度环和俯仰速度环跟踪前馈补偿参数的计算,并将该参数分别叠加到方位、俯仰跟踪控制回路,参与跟踪控制;采用模拟航路进行验证,该跟踪控制算法对速度2.5 Ma的高速运动目标,跟踪系统误差和随机误差均小于0.15 mrad。实验结果表明,该方法能有效提高光电跟踪仪对高速运动目标的跟踪精度,响应速度快、动态滞后小。     

CMOS图像传感器内置电源模块的研究与设计

电源模块是CMOS图像传感器芯片的一个重要组成部分,其性能直接影响着芯片的功耗以及所拍摄画面的质量.文中从CMOS图像传感器的像素结构和列读出电路原理出发,提出了一种低功耗、可编程控制的电源模块设计思想,并采用0.18μm CMOS工艺完成了电路设计.Hspice仿真结果表明,电源模块在启动70ms后能够生成稳定、正确的电压,其平均功耗小于1mW.     

光电跟踪系统高速运动目标快速跟踪算法

为了解决光电跟踪系统中高速运动目标快速识别、准确定位的问题,在深入研究相关跟踪算法的基础上,提出了一种基于分块模板相关跟踪与自适应波门相结合的快速跟踪算法,该算法利用分块矩阵与大模板矩阵之间的关系,得出了在四分块的情况下,计算量为原来的1/4,搜索范围为原来的4倍,大大提高了计算速度和搜索范围,且具有原始相关算法的高的跟踪精度,可以实时快速的跟踪上高速运动目标。     

小型风机最大功率点快速跟踪策略的仿真研究

风力发电系统的输出功率受外界因数和风速的影响。为了提高小型风机发电机组的转换效率,文中采用一种最大功率优化跟踪算法。以变步长来跟踪风速变化,当功率变化小于一个阈值时停止搜索,来实现最大功率收索的快速性和稳定性。以带齿轮箱6 kW的鼠笼异步式风力发电并网为基础,通过Matlab/Simulink软件仿真结果证实此种方法与定步长爬山法相比,能够达到快速跟踪最大功率点和避免达到最大功率点附近的时候频繁波动。     

应用于无线传感网的低功耗CMOS温度传感器

为了在较大的温度范围内改善传感器的线性并降低功耗,提出一种新的应用于无线传感网的频率输出温度传感器。采用了多谐振荡器电流转频率电路,主要由一个双向电流积分器组成,由电压窗口比较器驱动,由单独的1.2 V供给电压,并利用低成本的0.18 μm CMOS技术制作。实验结果表明,在?40°C到+120°C的温度范围内,该温度传感器表现出高线性的特点,实现了±1°C的误差,敏感性分别为340 Hz /°C,功耗为2.1 μW,面积为0.02 mm2,十分适合无线传感网的各种应用。     

Design procedure for two-stage CMOS opamp with optimum balancing of speed,power and noise

This article presents a basic two-stage CMOS opamp design procedure that provides the circuit designer with a means to establish optimised balancing between speed, power and noise for a given load condition. The proposed design steps allow opamp designers to optimise the power consumption for the given constraints of settling time, accuracy, noise and load. The key factor is to establish the optimum combination of ratios of transconductance of second stage to first stage and load capacitor to compensation capacitor. So, required accuracy and settling time can be established with minimum power consumption. Unlike the earlier reported design procedures, in this article a systematic method is presented to set the quiescent voltages at the transistors of the first and second stages of the opamp. This work will be helpful to select appropriate method of implementation of Miller compensation for given constraints. To verify the viability of the proposed design steps, SPICE simulation results for the proposed procedure are given. Best simulation results obtained on Tanner tool show settling time and power dissipation equal to 320 ns and 188.5 μW, respectively, for 5 pf capacitive load.     

Optimal sensor and path selection for target tracking in wireless sensor networks

This paper addresses target tracking in wireless sensor networks where the nonlinear observed system is assumed to progress according to a probabilistic state space model. Thus, we propose to improve the use of the quantized variational filtering by jointly selecting the optimal candidate sensor that participates in target localization and its best communication path to the cluster head. In the current work, firstly, we select the optimal sensor in order to provide the required data of the target and to balance the energy dissipation in the wireless sensor networks. This selection is also based on the local cluster node density and their transmission power. Secondly, we select the best communication path that achieves the highest signal‐to‐noise ratio at the cluster head; then, we estimate the target position using quantized variational filtering algorithm. The best communication path is designed to reduce the communication cost, which leads to a significant reduction of energy consumption and an accurate target tracking. The optimal sensor selection is based on mutual information maximization under energy constraints, which is computed by using the target position predictive distribution provided by the quantized variational filtering algorithm. The simulation results show that the proposed method outperforms the quantized variational filtering under sensing range constraint, binary variational filtering, and the centralized quantized particle filtering. Copyright © 2012 John Wiley & Sons, Ltd.     

基于OpenCV的交通视频运动目标检测与跟踪

智能交通系统（ITS）是目前世界交通运输领域正在研究和广泛关注的课题。OpenCV是一种用于数字图像处理和计算机视觉的函数库,由Intel公司开发。本文在目标检测方面,对采集到的交通视频进行灰度化、中值滤波、背景建模、二值化,背景差分等处理,可以较准确地检测出运动目标。在目标跟踪方面,提出了CamShift算法和Kalman滤波器相结合的方法,实现视频车辆的精确跟踪。最后,利用OpenCV的运动物体跟踪的数据结构、函数库,建立了一个视频车辆分析系统。用于道路上车辆的检测与跟踪,并具有良好的鲁棒性。     

A low power, low noise figure quadrature demodulator for a 60 GHz receiver in 65-nm CMOS technology

This paper presents the design of a low power (LP) and a low noise figure (NF) quadrature demodulator with an on-chip frequency divider for quadrature local oscillator (LO) signal generation. The transconductance stage of the mixer is implemented by an AC-coupled self-bias current reuse topology. On-chip series inductors are employed at the gate terminals of the differential input transconductance stage to improve the voltage gain by enhancing the effective transconductance. The chip is implemented in 65-nm LP CMOS technology. The demodulator is designed for an input radio frequency (RF) band ranging from 10.25 to 13.75 GHz. A fixed LO frequency of 12 GHz down-converts the RF band to an intermediate frequency (IF) band ranging from DC to 1.75 GHz. From 10 MHz to 1.75 GHz the demodulator achieves a voltage conversion gain (VCG) ranging from 14.2 to 13.2 dB, and a minimum single-sideband NF (SSB-NF) of 9 dB. The measured third-order input intercept point (IIP₃) is -3.3 dBm for a two-tone test frequency spacing of 1 MHz. The mixer alone draws a current of only 2.5 mA, whereas the complete demodulator draws a current of 7.18 mA from a 1.2 V supply. The measurement results for a frequency divider, which was fabricated individually, prior to being integrated with the quadrature demodulator, in 65-nm LP CMOS technology, are also presented in this paper.     

一种新的低功耗CMOS三值电路设计

提出一种新的静态电压型CMOS三值电路设计方案.该方案具有电路结构规则,输入信号负载对称等特点,是一种具有互补输入-输出的双轨三值逻辑电路.由于电路中同时采用pMOS和nMOS两种传输管,从而保证了输出信号具有完整的逻辑摆幅和高噪声容限.尤为重要的是该设计方案是基于标准CMOS工艺而无需修改阈值电压,且结构较简单.采用0.25μm CMOS工艺参数及3V电源的计算机模拟结果同时表明所提出的电路设计具有高速及低功耗的特点.     

采用双振荡器结构的低功耗CMOS温度传感器

为提高温度传感器的能量转换效率并降低功耗,提出了一种基于双振荡器的CMOS温度传感器。提出的温度传感器利用两个环形振荡器生成随温度变化的频率,通过调整线性频率的差斜率,来提高温度传感器的线性度,最后使用一个频率数字转换器完成数字输出。此外,还提出了一个制程补偿方案,经过一点校正法后可提高温度传感器的精确度。采用65 nm CMOS工艺进行了实现,面积仅为0.01mm2。测试结果显示,校正后提出温度传感器的分辨率为0.2℃/LSB,并且在0℃~125℃的温度范围内,20个实测样品的最大误差小于±1.2℃。相比其他类似传感器,当转换率高达480kS/s时,功率消耗500?W,即每次转换的能量最小,仅为0.001J/sample     

一种极低功耗的CMOS带隙基准源

随着SoC在便携产品中应用的迅猛发展,低功耗技术变得越来越重要。本文采用了0.18um的标准CMOS工艺来,设计了一种无电阻、工作在亚阈值区的低功耗、小面积的CMOS电压基准源。这个带隙基准可以灵活运用于极低功耗的SoC系统中。这个电路的电源电流大约为150nA,可以在1.5V～3.3V之间的电源电压下工作,基准源的输出电压的线性度为44.4ppm/V。当电源电压为1.5V,室温下带隙基准电路的输出电压为1.1126V,100Hz频率下的电源抑制比为-66dB,当温度在-20℃与80℃之间变化时,输出电压的温度系数是55ppm/℃。整个带隙基准的芯片面积是0.011mm2。     

几种CMOS VLSI的低功耗BIST技术

在分析全扫描内建自测试(BIST)较高测试功耗的基础上,总结出几种CMOS VLSI的低功耗BIST技术方案,包括减少待测电路(CUT)输入端的翻转次数、简化线性反馈移位寄存器(LFSR)结构、部分扫描低功耗BIST方法等.分析结果表明,这些方法不但在保证测试覆盖率的条件下,降低了测试平均功耗和峰值功耗,而且综合应用这几种方法将会使系统功耗指标达到最佳.     

A few CMOS transconductors optimized for low power and wide band operation

Maximizing the bandwidth of operation relative to dc power dissipation in complementary metal oxide semiconductor (CMOS) transconductors has been addressed in this article. It is proposed that the ac transconductance-to-dc power dissipation ratio is an appropriate objective function in this case. The general nature of the objective function is examined first. CMOS transconductors with two and four MOS working transistors are analyzed next. For structures of each kind, the ac transconductance-to-dc power dissipation ratio is maximized, and the optimal set of voltage variables is evaluated. For four-MOS structures with differential input signals, it is revealed that the choice of signal phase influences the objective function. The results of theoretical analyses are exhaustively tabulated. Numerical simulations are used to bring out the significance of the analytical expressions. This facilitates a comparison among several transconductors regarding the best possible ac transconductance-to-dc power dissipation ratio. These results are combined with HSPICE simulation results to suggest a few transconductor structures that are optimum with reference to the operation over wide bandwidths with lower power dissipation, high linearity and low harmonic distortion.The research was supported by grant no. N485 awarded to Dr. R. Raut by the Natural Science and Engineering Research Council (NSERC) of Canada.     

倾角传感器在太阳能跟踪系统中的应用研究

太阳能以其普遍性、永久性、无污染、分布广、利用方便等优点成为各国竞相研究和开发的热点。对太阳能跟踪控制系统中的倾角传感器应用进行了研究,以检测太阳能电池板的倾角,使得太阳能电池板在俯仰方向上与太阳的高度保持一致。设计了倾角传感器检测电路,通过对倾角传感器输出数据的采集和滤波处理,滤除了太阳能电池板在转动过程中因抖动而产生的随机误差信号,实现了在俯仰方向上的精确测量。     

低数据率条件下的目标跟踪

在低数据率条件下,采用基于卡尔曼预测估计的传统跟踪门对目标进行跟踪,容易出现误跟踪和航迹丢失,针对该问题,提出了一种两级跟踪门的解决方案。第一级跟踪门为组合跟踪门,它由运动学状态估计和目标的最大速度信息确定,目的是通过扩大跟踪门的面积使得目标测量尽可能地落在跟踪门之内;第二级跟踪门为由先验的和测量的幅度信息确定的特征跟踪门,其作用是对落入组合跟踪门内的测量进一步筛选,以区别出目标测量和杂波。只有那些同时满足两级跟踪门的测量才有可能来源于正在跟踪的目标,因此可以将其用于后续的数据关联和滤波更新。仿真结果表明,在低数据率条件下,采用该跟踪门方案的跟踪器的跟踪精度明显高于基于传统跟踪门 特征跟踪门和多跟踪门 特征跟踪门的跟踪器。     

面向RFID标签的COMS低功耗温度传感器设计

为了最大限度地提高无线射频识别（RFID）标签的操作距离,提出了一种集成于RFID标签芯片的超低功耗高精度CMOS温度传感器。传统的温度传感器主要采用带隙电路和ADC,而此类设计会消耗大量能量导致传感器功耗较高。提出传感器电路由新型数字环形振荡器,分频器,多路复用器和10位的数字计数器组成,温度转换成数字输出是在一个采样周期期间通获得过计数振荡器的时钟边缘数量得以实现。并且为了将温度灵敏度和动态范围最大化,使用的电源电压为0.3 v。振荡器的频率可以通过电容器组和堆叠晶体管进行数字修正。由于运用了阈值电压的温度依赖关系和MOS晶体管的载流子迁移率,因此与传统温度传感器相比,提出传感器的实现更加简单。通过0.18μm CMOS测试芯片获得的测量数据表明,提出的温度传感器分辨率为0.4°C/LSB,10位数字输出,校准后的可测量温度范围从-20°C到 95°C。采样频率为10Hz时,提出的传感器的功耗仅为92nW。     

A battery-less BLE smart sensor for room occupancy tracking supplied by 2.45-GHz wireless power transfer

Wireless power transfer (WPT) has emerged as a solution for supplying smart sensors for long-term battery-less deployment. Because the amount of power harvested by the smart sensor is limited due to WPT path loss, the optimization objective is twofold: achieving ultra-low-power operation for the sensing task and improving the harvesting efficiency even at low incident power. In this paper, we focus on the use case of a Bluetooth LE-connected motion detection system supplied by 2.45-GHz RF power. The full system (RF energy harvester, power management, sensor transducer and interface, control, data processing and wireless transmission) is implemented using low-power off-the-shelf components. In the sensing sub-system, ultra-low-power operation is achieved by the duty-cycling of the sensor interface and by an event-driven scheme for communication. In the harvesting sub-system, the design of the matching network and rectifier, combined with maximum power point tracking (MPPT), is optimized for increasing the power harvesting efficiency (PHE) at low incident power. Measurements show a total reduction in the power consumption for the sensing sub-system by a factor 20. When using custom WPT waveform with high peak-to-average power ratio, the RF energy harvester is functional with an incident RF power starting from −20 dBm. The smart sensor is able to perform its motion-detection task with an incident power as low as −17.3 dBm.     

High speed SOI CMOS image sensor with pinned photodiode on handle wafer

We have fabricated SOI CMOS active pixel image sensor with pinned photodiode on handle wafer. The structure of one pixel is a four-transistor type active pixel image sensor, which consists of a reset and a source follower transistor on seed wafer, and is comprised of a photodiode, a transfer gate, and a floating diffusion on handle wafer. The photodiode could be optimized for better quantum efficiency and low dark currents because the process of a photodiode on handle wafer is independent of that of transistors on seed wafer. Most of the wavelengths are absorbed within the visible range, because the optimized photodiode is located on the handle wafer. The response time of SOI CMOS active pixel sensor was about 2 times faster than that of bulk CMOS active pixel image sensor.