CMOS Quadrature VCO Implemented With Two First-Harmonic Injection-Locked Oscillators

This letter presents a new quadrature voltage-controlled oscillator (QVCO). The LC-tank QVCO consists of two first-harmonic injection-locked oscillators (ILOs). The outputs of one ILO are injected to the gates of the tail transistors on the other ILO and vice versa so as to force the two ILOs operate in quadrature. The proposed CMOS QVCO has been implemented with the TSMC 0.18 mum CMOS technology and the die area is 0.582 times 0.972 mm². At the supply voltage of 1.0 V, the total power consumption is 8.0 mW. The free-running frequency of the QVCO is tunable from 5.31 GHz to 5.75 GHz as the tuning voltage is varied from 0.0 V to 1.0 V. The measured phase noise at 1 MHz offset is -120.01 dBc/Hz at the oscillation frequency of 5.31 GHz and the figure of merit (FOM) of the proposed QVCO is about -185.48 dBc/Hz.     

Radiometric Calibration of LIDAR Intensity With Commercially Available Reference Targets

We present a new approach for radiometric calibration of light detection and ranging (LIDAR) intensity data and demonstrate an application of this method to natural targets. The method is based on 1) using commercially available sand and gravel as reference targets and 2) the calibration of these reference targets in the laboratory conditions to know their backscatter properties. We have investigated the target properties crucial for accurate and consistent reflectance calibration and present a set of ideal targets easily available for calibration purposes. The first results from LIDAR-based brightness measurement of grass and sand show that the gravel-based calibration approach works in practice, is cost effective, and produces statistically meaningful results: Comparison of results from two separate airborne laser scanning campaigns shows that the relative calibration produces repeatable reflectance values.      

New Sinusoidal Oscillators with Fully Uncoupled Control of Oscillation Frequency and Condition Using Three CCII+s

Using Sedra-Smith gyrator (IEEE Transactions on Circuit Theory 17, pp. 132–134, 1970) new realizations for grounded-resistor controlled sinusoidal oscillators using the plus-type second-generation current-conveyor (CCII+) can be systemically derived. Some of the new circuits enjoy the attractive feature of totally uncoupled frequency and condition of oscillation. Experimental and simulation results obtained using PSPICE are included.     

Precise Frequency and Phase Control of LSA Oscillators (Short Papers)

It is shown that consideration of both the external microwave circtuit and the dc bias applied to the diode are necessary in order to obtain satisfactory locking results with an LSA oscillator. When both are properly arranged, good control of both the operating frequency and the phase of an LSA oscillator at 3 GHz is demonstrated.     

Impulsive Control for T-S Fuzzy Model Based Chaotic Systems Consisting of Van der Pol Oscillators Coupled to Linear Oscillators

This paper proposes an impulsive control scheme for chaotic systems consisting of Van der Pol oscillators coupled to linear oscillators （VDPL） based on their Takagi-Sugeno （T-S） fuzzy models. A T-S fuzzy model is utilized to represent the chaotic VDPL system. By using comparison method, a general asymptotical stability criterion by means of linear matrix inequality （LMI） is derived for the T-S fuzzy model of VDPL system with impulsive effects. The simulation results demonstrate the effectiveness of the proposed scheme.     

An Analytical Comparison of Two Simple High-Q Gunn Oscillators (Short Papers)

This note compares and analyzes two commonly used simple waveguide Gunn oscillators in terms of their loaded Q-factors. Suitable design criteria are established for both, and two oscillators which were tested conformed well to these. It is concluded that although the more mechanically complex oscillator, which is in common use, has a greater flexibility, the simpler oscillator is adequate for most applications.     

Comparison of Photonic-Crystal-Enhanced Thermophotovoltaic Devices With and Without a Resonant Cavity

The ability to efficiently convert heat into usable energy using thermophotovoltaics (TPV) has been a topic of research for many years. Due to recent microfabrication advances, TPV and photonic crystals (PhC) have been the subject of renewed interest, especially as spectral emitters in TPV applications. However, PhC surface enhancements have also been shown to increase the efficiency of photon-to-current conversion for infrared photodetectors. Here, we investigate the potential efficiency enhancements gained by using PhC for a front-side TPV diode stage surface feature. A back reflecting plane was also added to increase the efficiency of TPV cells by introducing a resonant cavity. The simulations suggest an increased interaction time between photons and excitons leading to an increase in carrier generation. A simulated two-dimensional (2D) PhC consisting of Si₃N₄ rods in an ohmic contact material has demonstrated a possible 81% increase in absorption for a GaSb TPV cell.     

F150电路两种ISUP方案的比较

在推进本地电话网TUP电路改ISUP的过程中,石狮市电信局精心地选择更加合适的ISUP方案,并不断致力于优化、完善ISUP改造方法。1ISUP的意义和主要原理ITU-T的TUP标准缺少对补充业务的有效支持,并且TUP采用固定长度格式,因此在扩展中有较大难度。而通过ISUP的补充业务,其业务开发更具灵活性,并且ISUP定义了多种新参数,便于网络开放新的智能网业务,也易于集中智能外设的引入。由于ISUP目前已有技术规范,因此实现起来有一定的技术基础。F150的局间电路由若干个2Mbit/s的DT组成,电路数据主要由CCS和TER两层数据组成。CCS数…     

Analysis of Random Step Frequency Radar and Comparison With Experiments

Linear stepped frequency radar is used in wide-band radar applications, such as airborne synthetic aperture radar (SAR), turntable inverse SAR, and ground penetration radar. The frequency is stepped linearly with a constant frequency change, and range cells are formed by fast Fourier transform processing. The covered bandwidth defines the range resolution, and the length of the frequency step restricts the nonambiguous range interval. A random choice of the transmitted frequencies suppresses the range ambiguity, improves covert detection, and reduces the signal interference between adjacent sensors. As a result of the random modulation, however, a noise component is added to the range/Doppler sidelobes. In this paper, relationships of random step frequency radar are compared with frequency-modulated continuous wave noise radar and the statistical characteristics of the ambiguity function and the sidelobe noise floor are analyzed. Algorithms are investigated, which reduce the sidelobes and the noise-floor contribution from strong dominating reflectors in the scene. Theoretical predictions are compared with Monte Carlo simulations and experimental data     

OFDM系统的两种频率跟踪算法的性能比较

本文分析了残余频偏对OFDM系统性能的影响,针对OFDM系统中常见的两种频率跟踪算法,比较了它们在加性高斯白噪声信道、SUI- 2和SUI- 5信道环境下的性能。仿真表明,采用计算相位旋转的频率跟踪算法比基于循环前缀的频率跟踪算法的估计精度高。在信道最大多径时延较循环前缀长度小时,两种算法对系统性能影响均较小;在信道最大多径时延接近循环前缀长度时,基于循环前缀的频率跟踪算法的估计误差的标准偏差通常超过子载波间隔的1 %,系统会有明显的信噪比损失     

单点频与宽带扫频测试目标RCS的比较

通过对RCS测试方法中的单点频(连续波)与宽带扫频测试方法进行研究,得出宽带扫频技术在RCS测试过程中的重要性。从两种测试方法的不同测量步骤和测量原理,并结合测量结果进行分析,可以看到点频测量方法所得的结果不能全面反映目标的散射特性,并且分辨率和精度受到限制。而利用宽带扫频技术对目标的RCS特性进行分析,能够全面反映目标的散射特性,且可以提高测量精度和目标分辨率,进而指出了其广泛的应用前景。     

半导体器件Poisson方程数值解法的比较及改进

本文对半导体器件物理计算机模拟中非线性Poiccon方程的主要数值法——有限差分、有限元Newton法及Mayergoyz法进行了比较.计算结果表明Mayergoyz法具有编程简单、节省计算机贮存单元及收敛性好的优点,但运算速度随离散点增加而显著变慢.本研究将该法和SOR法结合起来,克服了上述缺点.     

两种抛物面形状的指向性传声器的比较

传声器系统指向性的实现主要有两种途径：一是通过特殊的声结构,二是通过传声器阵列。比较了一个带有抛物面形状反射面的传声器系统和与抛物面开口面积相同的圆形传声器阵列的差异。分别使用Kirchhoff-Helmholtz积分方程和阵列理论对这两种传声器系统的性能进行研究。数值模拟的结果表明,抛物面反射式传声器系统在高频时具有更高的灵敏度,其指向性通常也好于圆形传声器阵列。     

Direct Power Control of Active Filters With Averaged Switching Frequency Regulation

This paper has developed a direct power control (DPC) structure to improve the performance of an active filter. A control algorithm directly uses the instantaneous power terms as control variables to replace the current and voltage variables that are commonly used in proportional-integral (PI) control systems. Compared to the other DPC schemes that have been reported so far, the proposed algorithm is oriented to harmonic current compensation, for which the switching functions are redefined, the bandwidths of the two hysteresis comparators are dynamically adjusted, and consequently, the pulsewidth modulation (PWM) switching frequencies are regulated to eliminate the unnecessary short switching pulses, and the control system can be used directly and effectively for various types of nonlinear load compensation. With the proposed control scheme, full control of the active filter, including the line current and the dc bus voltage, can be realized within an integrated power control loop. The advantages of the proposed control strategy have been verified by simulation and experimental results on a 2-kVA laboratory prototype.      

Robust Linear Control of (Chaotic) Permanent-Magnet Synchronous Motors With Uncertainties

We solve the problem of set-point (respectively, tracking) control of a permanent-magnet synchronous motor via linear time-invariant (respectively, time varying) control. Our control approach is based on the physical properties of the machine: inherent stability and robustness to external disturbances. Our analysis is carried out under mild conditions, using cascaded systems theory. For all cases: constant operating point, trajectory tracking, and with known and unknown load, we show uniform global asymptotic stability of the closed-loop system with a linear controller that uses only velocity measurements. Furthermore, we explore natural extensions of our results to improve robustness with respect to external ldquodisturbancesrdquo and parametric uncertainties.     

Solving the ECG Forward Problem by Means of Standard h- and h-Hierarchical Adaptive Linear Boundary Element Method: Comparison With Two Refinement Schemes

The boundary element method (BEM) is a commonly used numerical approach to solve biomedical electromagnetic volume conductor models such as ECG and EEG problems, in which only the interfaces between various tissue regions need to be modeled. The quality of the boundary element discretization affects the accuracy of the numerical solution, and the construction of high-quality meshes is time-consuming and always problem-dependent. Adaptive BEM (aBEM) has been developed and validated as an effective method to tackle such problems in electromagnetic and mechanical fields, but has not been extensively investigated in the ECG problem. In this paper, the h aBEM, which produces refined meshes through adaptive adjustment of the elements’ connection, is investigated for the ECG forward problem. Two different refinement schemes: adding one new node (SH1) and adding three new nodes (SH3), are applied for the h aBEM calculation. In order to save the computational time, the h-hierarchical aBEM is also used through the introduction of the h-hierarchical shape functions for SH3. The algorithms were evaluated with a single-layer homogeneous sphere model with assumed dipole sources and a geometrically realistic heart-torso model. The simulations showed that h aBEM can produce better mesh results and is more accurate and effective than the traditional BEM for the ECG problem. While with the same refinement scheme SH3, the h-hierarchical aBEM can save the computational costs about 9% compared to the implementation of standard h aBEM.      

两种高频CMOS压控振荡器的设计与研究

设计了两种压控振荡器,一种为反相器环形振荡器,另一种为差分环形振荡器。采用0.18μm标准CMOS工艺进行模拟,后仿真的结果显示压控环形结构的最高频率达到3.3GHz,在1.8V电源下的功耗为2.34mW。对压控振荡器的最大工作频率、功耗、压频传输特性等进行了分析比较,总结了高性能压控振荡器应具备的条件。     

分段长定子直线电机的磁场定向控制与间接磁通控制的比较

分段长定子永磁直线电动机能够形成车道，是工业上物流系统中的一种有效方法。有种电机在控制上存在一些缺点，如存在齿槽力、过渡区存在力削弱以及饱和现象。本文利用有限元法得到的三维表并将其作为前馈量的方法来比较磁场定向控制和间接定子磁通控制，相应实验结果在文中给出。     

A Comparison of Tonographic-Trace Simulations Achieved by Two Systems: Nonlinear Elastic and Linear Viscoelastic

Twenty normal clinical tonographic traces were averaged and compared at 10-s intervals by means of two systems: 1) the decay curves of a linear viscoelastic mathematical model having a single degree of freedom, and 2) nonlinear elastic models, including the classical (or current) Grant model. The linear viscoelastic model provided a considerably better match than the other models. So far as degree of match and facility of outflow values were concerned, the study showed the effect on the models of various investigators' formulations of ocular rigidity, corneal indentation, and tonometer calibration. In precise work facility of outflow values should be reported only if a measure of the degree of fit to the tonogram is given.     

High Voltage Tolerant Linear Regulator With Fast Digital Control for Biasing of Integrated DC-DC Converters

Integrated DC-DC converters switching above 100MHz dramatically reduce the footprint of the inductors and capacitors while improving droop response. Unfortunately, such converters utilize advanced digital CMOS processes with the maximum input voltage below 2 V. We propose a fully integrated linear regulator that enables doubling of the converter input voltage by properly biasing stacked drivers and bridge transistors. By implementing fast digital control the linear regulator meets the transient current demand of the converter without resorting to off-chip decoupling capacitors. In a 90 nm CMOS process, the 2.4V input, 1.2 V output, linear regulator occupies 0.03 mm² for a plusmn1 A rating. A 288 ps response time and 97.5% current efficiency result in a 2.84times improvement in speed-power figure of merit over previous work