共查询到20条相似文献,搜索用时 31 毫秒
1.
Wende Chen Honkala I.S. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1990,36(3):664-671
The authors prove combinatorial lower bounds for K q (n ,R ), the minimal cardinality of any q -ary code of length n and covering radius R . Tables of lower bounds for K q(n ,R ) are presented for q =3, 4, 5 相似文献
2.
Peransin J.-M. Vignaud P. Rigaud D. Vandamme L.K.J. 《Electron Devices, IEEE Transactions on》1990,37(10):2250-2253
The 1/f noise in normally-on MODFETs biased at low drain voltages is investigated. The experimentally observed relative noise in the drain current S I/I 2 versus the effective gate voltage V G=V GS-V off shows three regions which are explained. The observed dependencies are S I/I 2∝V G m with the exponents m =-1, -3, 0 with increasing values of V G. The model explains m =-1 as the region where the resistance and the 1/f noise stem from the 2-D electron gas under the gate electrode; the region with m =0 at large V G or V GS≅0 is due to the dominant contribution of the series resistance. In the region at intermediate V G , m =-3, the 1/f noise stems from the channel under the gate electrode, and the drain-source resistance is already dominated by the series resistance 相似文献
3.
The usual approximate expression for measured f T =[g m/2π (C gs+C gd)] is inadequate. At low drain voltages just beyond the knee of the DC I -V curves, where intrinsic f t is a maximum for millimeter-wave MODFETs, the high values of C gd and G ds combine with the high g m to make terms involving the source and drain resistance significant. It is shown that these resistances can degrade the measured f T of a 0.30-μm GaAs-AlGaAs MODFET from an intrinsic maximum f T value of 73 GHz to a measured maximum value of 59 GHz. The correct extraction of maximum f T is essential for determining electron velocity and optimizing low-noise performance 相似文献
4.
Poly-Si resistors with an unimplanted channel region (and with n-type source/drain regions) can exhibit a nonhyperbolic sine (non-sinh) I -V characteristic at low V DS and an activation energy which is not simply decreasing monotonically with increasing V DS. These phenomena are not explained by conventional poly-Si resistor models. To describe these characteristics, a self-consistent model which includes the effects of a reverse-biased diode at the drain end is presented. Numerical simulation results show excellent agreement with experiment in regard to the shape of the I -V characteristic and of the effective activation energy as a function of V DS 相似文献
5.
The DC and microwave properties of In0.52Al0.48 Al/InxGa1-xAs (0.53⩽x ⩽0.70) heterostructure insulated gate field-effect transistors (HIGFETs) with a quantum well channel design are presented. DC and microwave transconductances (g m) are enhanced as the In content is increased in the InGaAs channel. An intrinsic microwave g m value of 428 mS/mm and a K -factor of 1140 mS/mm-V have been obtained for 1.0-μm gate length with the 65% In channel devices. The sheet charge density, drift mobility, transconductance, current-gain cutoff frequency (f T), and maximum oscillation frequency (f max) all show a continuous improvement up to 65% In content ( f T=22.5 GHz with 53% and f T=27 GHz with 65% In; the corresponding f max change is from 6.5 to 8 GHz). The device performance degrades as the In content is increased to 70%. DC and microwave characteristics show the presence of negative differential resistance (NDR) up to 2.7 GHz 相似文献
6.
《Electron Devices, IEEE Transactions on》1990,37(1):153-158
The fabrication of a silicon heterojunction microwave bipolar transistor with an n+ a-Si:H emitter is discussed, and experimental results are given. The device provides a base sheet resistance of 2 kΩ/□ a base width 0.1 μm, a maximum current gain of 21 (V CE=6 V, I c=15 mA), and an emitter Gummel number G E of about 1.4×1014 Scm-4. From the measured S parameters, a cutoff frequency f t of 5.5 GHz and maximum oscillating frequency f max of 7.5 GHz at V CE=10 V, I c=10 mA are obtained 相似文献
7.
Malik R.J. Chand N. Nagle J. Ryan R.W. Alavi K. Cho A.Y. 《Electron Device Letters, IEEE》1992,13(11):557-559
Temperature-dependent measurements from 25 to 125°C have been made of the DC I -V characteristics of HBTs with GaAs and In0.53Ga0.47As collector regions. It was found that the GaAs HBTs have very low output conductance and high collector breakdown voltage BV CEO>10 V at 25°C, which increases with temperature. In striking contrast, the In0.53Ga0.47As HBTs have very high output conductance and low BV CEO~2.5 V at 25°C, which actually decreases with temperature. This different behavior is explained by the >104 higher collector leakage current, I CO, in In0.53Ga0.47As compared to GaAs due to bandgap differences. It is also shown that device self-heating plays a role in the I -V characteristics 相似文献
8.
A three-terminal circuit (power, ground, and output) that provides a DC output voltage equal to the MOS threshold voltage V T is presented. The circuit uses the four-terminal extractor topology of Z. Wang (1992), but it adds self-biasing and a two-transistor differential amplifier to provide a ground-referenced output voltage 相似文献
9.
Self-aligned high-frequency InP/InGaAs double heterojunction bipolar transistors (DHBTs) have been fabricated on a Si substrate. A current gain of 40 was obtained for a DHBT with an emitter dimension of 1.6 μm×19 μm. The S parameters were measured for various bias points. In the case of I C=15 mA, f T was 59 GHz at V CE=1.8 V, and f max was 69 GHz at V CE=2.3 V. Due to the InP collector, breakdown voltage was so high that a V CE of 3.8 V was applied for I C=7.5 mA in the S -parameter measurements to give an f T of 39 GHz and an f max of 52 GHz 相似文献
10.
Chen J. Solomon R. Chan T.-Y. Ko P.K. Hu C. 《Electron Devices, IEEE Transactions on》1992,39(10):2346-2353
11.
Greenberg D.R. del Alamo J.A. Harbison J.P. Florez L.T. 《Electron Device Letters, IEEE》1991,12(8):436-438
Molecular beam epitaxy (MBE)-grown L g=1.7-μm pseudomorphic Al0.38Ga0.62As/n+-In0.15Ga 0.85As metal-insulator-doped channel FETs (MIDFETs) are presented that display extremely broad plateaus in both f T and f max versus V GS, with f T sustaining 90% of its peak over a gate swing of 2.6 V. Drain current is highly linear with V GS over this swing, reaching 514 mA/mm. No frequency dispersion in g m up to 3 GHz was found, indicating the absence of electrically active traps in the undoped AlGaAs pseudoinsulator layer. These properties combine to make the pseudomorphic MIDFET highly suited to linear, large-signal, broadband applications 相似文献
12.
Interpretation and control of C -V measurementsusing pattern recognition and expert system techniques
Walls J.A. Walton A.J. Robertson J.M. 《Semiconductor Manufacturing, IEEE Transactions on》1991,4(3):250-262
The authors demonstrate how a pattern-recognition system can be applied to the interpretation of capacitance-voltage (C -V ) curves on an MOS test structure. By intelligently sequencing additional measurements it is possible to accurately extract the maximum amount of information available from C -V and conductance-voltage (G -V ) measurements. The expert system described, (CV -EXPERT), is completely integrated with the measurement, instrumentation, and control software and is thus able to call up a sequence of individually tailored tests for the MOS test structure under investigation. The prototype system is able to correctly identify a number of process faults, including a leaky oxide, as shown. Improvements that could be gained from developing rules to coordinate G -V , capacitance-time, and doping profile measurements simply by recognizing the important factors in the initial C - V measurement are illustrated 相似文献
13.
Approximate confidence bounds for reliability, R =Pr{X >Y |X ,Y }, are obtained, where X and Y are independent normal (Gaussian) random variables, and X and Y are vectors of measurements for X and Y , respectively. Balanced 1-way ANOVA (analysis of variants) random effect models are assumed for the populations of X and Y . Confidence bounds are derived for R under three cases for standard deviations, σx and σy. An example shows how the results are used 相似文献
14.
Yiqi Zhuang Qing Sun 《Electron Devices, IEEE Transactions on》1991,38(11):2540-2547
Accelerated life tests with high-temperature storage and electric aging for n+-p-n silicon planar transistors were carried out. Current gain h FE increases monotonously with time during the tests, and the h FE drift is correlated with initial measured 1/f noise in the transistors, i.e. the drift amount significantly increases with the increase of noise level. The correlation coefficient of relative drift Δh FE /h FE and 1/f noise spectral density S iB(f ) is far larger than that of Δ h FE/h FE and initial DC parameters of the transistors. A quantitative theory model for the h FE drift has been developed and explains the h FE drift behavior in the tests, which suggests that the h FE drift and 1/f noise can be attributed to the same physical origin, and both are caused by the modulation of the oxide traps near the Si-SiO2 interface to Si surface recombination. 1/f noise measurement, therefore, may be used as a fast and nondestructive means to predict the long-term instability in bipolar transistors 相似文献
15.
The authors study the multiwindow spectral analysis method as it applies to the detection of sinusoidal signals. They examine the probability of false alarm P FA. The total P FA (sinusoidal frequency unknown) is shown analytically to be bounded below by the order statistics (minimum) of BM /K independent identically distributed (i.i.d.) beta variates, where M is the length of the data record used in the detection, K the number of windows, and B the width of the frequency band of interest. Simulation results indicate a much larger bound, the minimum of BM i.i.d. beta variates. It is shown that for real signals, the assumptions made in the derivation of the detector break down at frequencies close to zero and to half the sampling frequency 相似文献
16.
An m -consecutive-k -out-of-n :F system, consists of n components ordered on a line; the system fails if and only if there are at least m nonoverlapping runs of k consecutive failed components. Three theorems concerning such systems are stated and proved. Theorem one is a recursive formula to compute the failure probability of such a system. Theorem two is an exact formula for the failure probability. Theorem three is a limit theorem for the failure probability 相似文献
17.
Ng G.I. Pavlidis D. Tutt M. Weiss R.M. Marsh P. 《Electron Devices, IEEE Transactions on》1992,39(3):523-532
Extensive bias-dependent and temperature-dependent low-frequency (LF) noise measurements were performed on lattice-matched and strained In0.52Al0.48As/InxGa1-x As(0.53<x <0.70) HEMTs. The input-noise voltage spectra density is insensitive to V DS bias and shows a minimum at V GS corresponding to the peak g m condition. The corresponding output-noise voltage spectral density, which depends strongly on the gain of the devices, increases with V DS. The input noise was rather insensitive to indium (In) content. Temperature-dependent low-frequency noise measurements on these devices reveal shallow traps with energies of 0.11, 0.15, and 0.18 eV for 60%, 65%, and 70% In HEMTs. Noise transition frequencies for these devices were on the order of 200-300 MHz and remain almost the same for different channel In content and V DS bias 相似文献
18.
A technique for the measurement of device derivatives d NV /dI N of arbitrary order N described. Measurement is accomplished by injecting a test current composed of the sum of N square waves into the rest device, and then multiplying the corresponding voltage change by the product of those same square waves, followed by low-pass filtering. The algorithm is implemented in real time using a mixture of analog and digital circuitry, and its application to semiconductor laser control in high-speed optical communications is described 相似文献
19.
Detailed microwave characterization of a recently fabricated In 0.52Al0.48As/n+-In0.53Ga 0.47As MISFET reveals that high values of current-gain cutoff frequency (f T) and unilateral-gain cutoff frequency (f max) are obtained for a broad range of gate bias voltage values. A significant peak in f T and f max has also been observed at high gate-source bias values. The peak coincides with the onset of electron accumulation at the heterointerface and is attributed to reduced ionized impurity scattering coupled with reduced drain conductance. This result suggests an improved device structure that optimizes operation in the accumulation regime 相似文献
20.
Seung-Moon Yoo Ejaz Haq Seung-Hoon Lee Yun-Ho Choi Soo-In Cho Nam-Soo Kang Daeje Chin 《Solid-State Circuits, IEEE Journal of》1993,28(4):499-503
Wide-voltage-range DRAMs with extended data retention are desirable for battery-operated or portable computers and consumer devices. The techniques required to obtain wide operation, functionality, and performance of standard DRAMs from 1.8 V (two NiCd or alkaline batteries) to 3.6 V (upper end of LVTTL standard) are described. Specific techniques shown are: (1) a low-power and low-voltage reference generator for detecting V CC level; (2) compensation of DC generators, V BB and V PP, for obtaining high speed at reduced voltages; (3) a static word-line driver and latch-isolation sense amplifier for reducing operating current; and (4) a programmable V CC variable self-refresh scheme for obtaining maximum data retention time over a full operating range. A sub-50-ns access time is obtained for a 16 M DRAM (2 M×8) by simulation 相似文献