共查询到20条相似文献,搜索用时 15 毫秒
1.
CMOS电路中的闩锁效应研究 总被引:6,自引:2,他引:4
闩锁效应是功率集成电路中普遍存在的问题。文中分析了CMOS结构中的闩锁效应的起因,提取了用于分析闩锁效应的集总器件模型,给出了产生闩锁效应的必要条件,列举了闩锁效应的几种测试方法。最后,介绍了避免发生闩锁效应的几种方法。 相似文献
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《Antennas and Propagation Magazine, IEEE》1992,34(6):17-22
Early work on magnetrons and on radar for the Japanese Navy is summarized. The development, during World War II, of microwave radars for various warships and for land-based use, is discussed. Research on super-high-power-output magnetrons for shooting down aircraft is described. Radar for the Japanese army is also described 相似文献
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16DAPSK+OFDM及其在数字调幅广播中应用 总被引:2,自引:0,他引:2
本文提出一种新的频域16DAPSK+OFDM。并讨论它的频域差分调制和解调,然后在白高斯信道分析它的误比特性能。同时域16DASK+OFDM相比,频域16DAPSK+OFDM可用于信道特性随时间变化更快的应用。最后,在典型的调幅(AM)波段信道对两者误比特性能进行了仿真。结果表明,时域和频域16DPSK+OFDM都可用于中短波信道。在中波信道,时域16DAPSK比例域16DAPSK性能要好,在短波信道,频域16DAPSK比时域16DAPSK性能要好。另外,两者调制和解调的计算复杂度基本一样,且都不需要信息道均衡。 相似文献
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《Microwave Theory and Techniques》1981,29(11):1165-1173
This paper presents a theory for broad-band matching of stripline junction circulators for operation in two or more frequency bands. In this theory it is assumed that the matching network is composed of cascaded transmission line transformers each of which is an odd multiple of a quarter-wavelength at the center frequencies. The conditions for simultaneous Chebyshev response in multiple frequency bands are determined, and it is investigated to what extent these conditions can be satisfied by stripline circulator junctions. Thus by using a first-order theory, it is shown that if a circulator junction, adjusted for double frequency operation, is matched for Chebyshev response by a transformer of proper length around one of the circulation frequencies then it is also matched for Chebyshev response around the other circulation frequency, provided that the same operation mode is used above and below material resonance. A routine for broad-band multiple frequency matching is proposed for junctions where Chebyshev response is not obtainable. Finally the properties of some externally matched circulators designed according to the theories are shown. 相似文献
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A theoretical analysis of the fault coverage of conformance test sequences for communication protocols specified as finite state machines is presented. Faults of different types are considered, and their effect on testing is analyzed. The interaction between faults of different categories and the impact it has on conformance testing is investigated. Fault coverage is defined for the testing of both incompletely-specified machines (ISMs) and completely-specified machines (CSMs). An algorithm is presented to generate test sequences with maximal fault coverage for the testing of ISMs. It is then augmented for the testing of CSMs, and finally a technique is presented for generating test sequences which provides guaranteed maximal fault coverage for the conformance testing of communication protocols 相似文献
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Kachroo P. Shedied S.A. Bay J.S. Vanlandingham H. 《IEEE transactions on systems, man and cybernetics. Part C, Applications and reviews》2001,31(1):35-41
A herding dog and sheep problem is studied where the agent “dog” is considered the control action for moving the agent “sheep” to a fixed location using the dynamics of their interaction. The problem is solved for the deterministic case using dynamic programming. Proofs are provided for the correctness of the algorithms. The algorithm is analyzed for its complexity. A software package developed for experimentation is described 相似文献
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Bhardwaj S. Williams R. J. Acampora A. S. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(5):1851-1859
A multiple-input multiple-output (MIMO) downlink system in which data is transmitted to two users over a common wireless channel is considered. The channel is assumed to be fixed for all transmissions over the period of interest and the ratio of anticipated average arrival rates for the two users, also known as the relative traffic rate, is the system design parameter. A packet-based traffic model is considered where data for each user is queued at the transmit end. A queueing analog for this system leads to a coupled queueing system for which a simple policy is known to be throughput-optimal under Markovian assumptions. Since an exact expression for the performance is not available, as a measure of performance (in heavy traffic), a diffusion approximation is established. This diffusion process is a two-dimensional (2-D) Semimartingale Reflecting Brownian Motion (SRBM) living in the positive quadrant of 2-D space 相似文献
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Shamir G.I. Costello D.J. Jr. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2004,50(8):1620-1635
A lower bound is derived on the achievable redundancy for universal lossless coding of parametric sources with piecewise stationary, abruptly changing, occasionally repeating statistics. In particular, it is shown that if the number of repeating statistical parameter vectors (or states) is not too large, for any uniquely decipherable code, for almost every set of states that govern all the different segments in the data sequence, for almost every arrangement of these states in the different segments, and for almost every vector of transition times, the minimum achievable redundancy is composed of 0.5 log d extra code bits for each unknown component of each state, log m extra code bits for each unknown transition time, and log s extra code bits for each repetition of a state, where d is the average duration of each state in the input string, TO is the average length of a segment, and s is the total number of states. If s is essentially large compared to TO, it is shown that the minimum redundancy is composed of 0.5 log 77i bits for each unknown component in each segment and log TO bits for each unknown transition time, which is the same lower bound as that of general piecewise stationary sources (PSSs). These results are true also in the minimax and maximin senses. The lower bound is shown to be achievable through construction of mixture and estimation based codes. Different special cases are reviewed, and it is shown that unless s is essentially large compared to m, optimal codes that are designed particularly for sources with repeating statistics outperform codes designed for PSSs when coding sources with repeating statistics. In particular, the bound for general PSSs is shown to be a special case of the new bound. 相似文献
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The performance of type-II hybrid automatic repeat request (ARQ) is compared to that of fixed-rate type-I hybrid ARQ for meteor-burst communications. Maximum throughput is obtained for meteor-burst communications by using a transmission scheme for which the information rate of the code, varies in response to the fluctuations in the power received from a meteor trail. For type-II hybrid ARQ, a variation in the code rate is inherent in the coding scheme. On the first transmission that is made for a data block, a code of relatively high rate is used, but if an additional transmission is required, only redundant symbols are sent, and this reduces the overall rate of the code. The performance measure is the throughput per trail, which is defined as the expected number of successfully received information bits for a given meteor trail. The authors also develop an approximation for the average value of the throughput, averaged over the parameters of the meteor trail. Numerical results for Reed-Solomon codes are included to illustrate the relative performance of the various schemes. It is shown that the throughput is larger for type-II hybrid ARQ than for either fixed-rate type-I hybrid ARQ or ARQ without forward-error-correction 相似文献
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An assessment of wide bandgap semiconductors for power devices 总被引:2,自引:0,他引:2
Hudgins J.L. Simin G.S. Santi E. Khan M.A. 《Power Electronics, IEEE Transactions on》2003,18(3):907-914
An advantage for some wide bandgap materials, that is often overlooked, is that the thermal coefficient of expansion (CTE) is better matched to the ceramics in use for packaging technology. It is shown that the optimal choice for uni-polar devices is clearly GaN. It is further shown that the future optimal choice for bipolar devices is C (diamond) owing to the large bandgap, high thermal conductivity, and large electron and hole mobilities. A new expression relating the critical electric field for breakdown in abrupt junctions to the material bandgap energy is derived and is further used to derive new expressions for specific on-resistance in power semiconductor devices. These new expressions are compared to the previous literature and the efficacy of specific power devices, such as heterojunction MOSFETs, using GaN are discussed. 相似文献
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《Microwave Theory and Techniques》1987,35(10):893-897
Theory for quasi-TEM modes propagating in a transversely inhomogeneous (multidielectric), longitudinally uniform transmission line, previously derived for time-harmonic waves, is derived for transient signals. It is seen that, while the starting point for the theory is completely different, the result is similar to the time-harmonic theory, and previously derived properties for propagating modes also apply in the transient case. The range of applicability is discussed with a simple example. 相似文献
13.
文章分析了动态环境下多普勒频移的产生,研究了多普勒频移的估算方法并建立了数学模型,在此基础上提出了一种运用DSP结合专用的DDS芯片AD9954模拟多普勒频移的方案。并根据所模拟数据的要求选择了一种可行AD9954的工作模式,介绍了参数的计算方法,给出了DSP控制AD9954进行多普勒频移模拟的程序流程。 相似文献
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A control system for the temperature of food in a cooking pot is introduced. The cooking pot is heated on a consumer cooking hob. The temperature of the pot side is used as input for the controller. It is measured by an infrared detector. The infrared detector is a thermopile. The sensor signal is evaluated by a rule-based control algorithm. The system is simple, reliable, and very user friendly. An exact temperature settlement in a consumer hob is available for the first time. The system is used for automatic cooking 相似文献
15.
A tight upper bound on the decoding error probability is derived for block-coded modulation structures where an M-ary phase shift keying (M-PSK) signal constellation is employed. This bound, called a tangential sphere bound, is tight for very low (as well as for high) signal-to-noise ratios (SNRs). Berlekamp's tangential union bound, previously derived for binary codes, can be derived for an M-PSK block coded modulation structure as well. However, it is proven that our tangential sphere bound is tighter than Berlekamp's (1980) tangential bound. For particular schemes, it is shown that for low SNRs our bound is considerably tighter than the tangential bound. As one of the examples, a multistage decoder is considered 相似文献
16.
基于SISE方程的广义gamma分布参数估计方法 总被引:2,自引:0,他引:2
广义gamma分布是近年来用于SAR图像统计建模重要分布之一,参数估计是制约其应用的核心问题。该文提出了一种新的参数估计方法。首先分析了的对数累积量参数估计方法(Mehtod-of- Log-Culmulants, MoLC)的不足,接着推导了基于SISE (Scale-Independent-Shape-Estimation)方程的参数估计表达式,并给出了具体的求解方法。最后,利用蒙特卡洛仿真的实验结果表明,该文方法稳定性和有效性优于MoLC。 相似文献
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The error due to discretization in a method-of-moments analysis of a parallel plate or metal-insulator-metal (MIM) capacitor is discussed. A technique related to Richardson extrapolation is used to develop a model for the error due to subsectional discretization. The results are for Galerkin's method using rooftop basis functions; however, the technique can be applied to any variational moment-method calculation. An expression is presented for the error in capacitance calculations, which is shown to hold for changes in geometry and dielectric constant. In addition, the expression for error is shown to be accurate for a wide range of meshing geometries. Surprisingly, the error model is not an upper bound, but rather is met nearly in equality for all geometries considered. Thus, the error may be simply subtracted from the calculated value for a more accurate result 相似文献
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本文仅对于简化模型探讨了关于奥罗管(orotron)的效率(起振问题),导出了影响效率的重要参量Zc,给出了关于这种器件的电子注与场互作用的大信号自洽解,并举例对实际参量进行了数值计算。计算结果指出,为了保证奥罗管能在宽频范围内调谐的前提下研制实用的器件,在设计准光腔的时候,不仅应追求高的品质因数,还应使与电子注作用的光栅上的模斑尽还能伸长和展宽,对于所采用的紧贴光栅表面掠过的电子注,应尽可能提高其电流值。 相似文献
19.
The cumulative function for the number of failures for a unit which is subjected to minimal repair after each failure is a nonstationary Poisson process. In this note, a simple method for obtaining this result is presented. A conditional probability approach is used for the derivation 相似文献
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《Lightwave Technology, Journal of》2008,26(14):2142-2154