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51.
Yuhua Cheng Min-Chie Jeng Zhihong Liu Jianhui Huang Mansun Chan Kai Chen Ping Keung Ko Chenming Hu 《Electron Devices, IEEE Transactions on》1997,44(2):277-287
A new physical and continuous BSIM (Berkeley Short-Channel IGFET Model) I-V model in BSIM3v3 is presented for circuit simulation. Including the major physical effects in state-of-the art MOS devices, the model describes current characteristics from subthreshold to strong inversion as well as from the linear to the saturation operating regions with a single I-V expression, and guarantees the continuities of Ids, conductances and their derivatives throughout all Vgs, Vds, and Tbs, bias conditions. Compared with the previous BSIM models, the improved model continuity enhances the convergence property of the circuit simulators. Furthermore, the model accuracy has also been enhanced by including the dependencies of geometry and bias of parasitic series resistances, narrow width, bulk charge, and DIBL effects. The new model has the extensive built-in dependencies of important dimensional and processing parameters (e.g., channel length, width, gate oxide thickness, junction depth, substrate doping concentration, etc.). It allows users to accurately describe the MOSFET characteristics over a wide range of channel lengths and widths for various technologies, and is attractive for statistical modeling. The model has been implemented in the circuit simulators such as Spectre, Hspice, SmartSpice, Spice3e2, and so on 相似文献
52.
Sheng-Fuh Chang Yng-Huey Jeng Jia-Liang Chen 《Electronics letters》2004,40(1):38-39
A step-impedance bandpass filter is presented for multimode wireless LANs. The filter has a new dual-band feature of two tunable passbands at desired frequencies and high out-of-band suppression, generated by incorporating step-impedance resonators in a comb-filter topology. It saves more than half the circuit size compared with the switch-type dual-band topology. The simulation and measurement results show the dual-band feature of two passbands at 2.45 and 5.75 GHz with 85 dB suppression at 3.5 GHz. 相似文献
53.
Shiun-Chi Jan Shyh-Kang Jeng 《Vehicular Technology, IEEE Transactions on》1997,46(4):1021-1026
A novel method for microcellular communications to predict propagation characteristics is presented in this paper. It takes into account multiple reflections among walls, ground, vehicles, as well as the transmission/reflection due to groups of trees. Although these are three-dimensional (3-D) problems, we can combine two-dimensional (2-D) ray tracing and simple 3-D geometric considerations to solve them in a very efficient way. We have investigated the propagation loss versus size, number, and locations of vehicles and groups of trees on a safe island. Our results show that the radio wave propagation exhibits severe fast fading, attenuation, and blockage due to reflection, transmission, and shadowing, respectively 相似文献
54.
Cheng-I Chang Xiao-Li Zhao Althouse M.L.G. Jeng Jong Pan 《Geoscience and Remote Sensing, IEEE Transactions on》1998,36(3):898-912
An orthogonal subspace projection (OSP) method using linear mixture modeling was recently explored in hyperspectral image classification and has shown promise in signature detection, discrimination, and classification. In this paper, the OSP is revisited and extended by three unconstrained least squares subspace projection approaches, called signature space OSP, target signature space OSP, and oblique subspace projection, where the abundances of spectral signatures are not known a priori but need to be estimated, a situation to which the OSP cannot be directly applied. The proposed three subspace projection methods can be used not only to estimate signature abundance, but also to classify a target signature at subpixel scale so as to achieve subpixel detection. As a result, they can be viewed as a posteriori OSP as opposed to OSP, which can be thought of as a priori OSP. In order to evaluate these three approaches, their associated least squares estimation errors are cast as a signal detection problem ill the framework of the Neyman-Pearson detection theory so that the effectiveness of their generated classifiers can be measured by receiver operating characteristics (ROC) analysis. All results are demonstrated by computer simulations and Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data 相似文献
55.
Jagannathan B. Khater M. Pagette F. Rieh J.-S. Angell D. Chen H. Florkey J. Golan F. Greenberg D.R. Groves R. Jeng S.J. Johnson J. Mengistu E. Schonenberg K.T. Schnabel C.M. Smith P. Stricker A. Ahlgren D. Freeman G. Stein K. Subbanna S. 《Electron Device Letters, IEEE》2002,23(5):258-260
This paper reports on SiGe NPN HBTs with unity gain cutoff frequency (fT) of 207 GHz and an fMAX extrapolated from Mason's unilateral gain of 285 GHz. fMAX extrapolated from maximum available gain is 194 GHz. Transistors sized 0.12×2.5 μm2 have these characteristics at a linear current of 1.0 mA/μm (8.3 mA/μm2). Smaller transistors (0.12×0.5 μm2) have an fT of 180 GHz at 800 μA current. The devices have a pinched base sheet resistance of 2.5 kΩ/sq. and an open-base breakdown voltage BVCEO of 1.7 V. The improved performance is a result of a new self-aligned device structure that minimizes parasitic resistance and capacitance without affecting fT at small lateral dimensions 相似文献
56.
Chung J. Jeng M. Moon J.E. Wu A.T. Chan T.Y. Ko P.K. Hu C. 《Electron Device Letters, IEEE》1988,9(4):186-188
A photoresist-ashing process has been developed which, when used in conjunction with conventional g-line optical lithography, permits the controlled definition of deep-submicrometer features. The ultrafine lines were obtained by calibrated ashing of the lithographically defined features in oxygen plasma. The technique has been successfully used to fabricate MOSFETs with effective channel length as small as 0.15 μm that show excellent characteristics. An NMOS ring oscillator with 0.2-μm devices has been fabricated with a room-temperature propagation delay of 22 ps/stage. Studies indicate that the thinning is both reproducible and uniform so that it should be usable in circuit as well as device fabrication. Since most polymer-based resist materials are etchable with an oxygen plasma, the basic technique could be extended to supplement other lithographic processes, including e-beam and X-ray processes, for fabricating both silicon and nonsilicon devices and circuits 相似文献
57.
Yu-Der Lee Hong-Bing Tsai Jaw-Tarng Jeng 《Journal of polymer science. Part A, Polymer chemistry》1988,26(8):2039-2046
The effect of various phase transfer agents on the interfacial polycondensation of bisphenol A with isophthaloyl chloride was investigated. It was found that the transfer rate of bisphenolate and, thus, the reaction rate of polycondensation were increased with an increasing lipophilicity of the phase transfer agent, i.e. TBAC > TEBAC > TEAC, whereas the equilibrium of bisphenolate between the organic phase and the aqueous phase was hardly affected. Moreover, experimental evidence indicated that a phase transfer agent of high lipophilicity reduced the hydrolysis of the acid chloride, an important aspect in interfacial polycondensation. 相似文献
58.
Kang-Wei Fan Ching-Chih Weng Zou-Min Tsai Huei Wang Shyh-Kang Jeng 《Microwave and Wireless Components Letters, IEEE》2005,15(1):19-21
Two K-band active band-pass filters using 0.15-/spl mu/m GaAs pHEMT technology, with one fixed-frequency and the other tunable, are designed, fabricated, and tested. The fixed-frequency filter has its central frequency at 22.6 GHz, with 900-MHz bandwidth (4%). The tunable filter can be tuned from 19.5 to 21.5 GHz with the same bandwidth. Both circuits have a common size of 1 mm /spl times/ 1 mm. To our knowledge, the tunable filter is the highest frequency tunable active filter ever reported. 相似文献
59.
Jeng Kuang Hwang Yung-Chang Chen 《Signal Processing, IEEE Transactions on》1993,41(2):727-741
A novel periodogram-based maximum-likelihood algorithm is proposed for a frequency estimation problem. It is called an alternating notch-periodogram algorithm (ANPA), since the original multidimensional maximum likelihood problem is decomposed into a sequence of much simpler one-dimensional problems of finding the peaks of notch periodograms. The ANPA achieves superresolution and a very low SNR threshold and can be computed and implemented in several efficient ways. First, with FFT and a concurrent Gram-Schmidt procedure using Schur's recursions, the notch periodogram can be computed without any costly eigendecomposition and matrix inversion. This approach can further lead to a mapping of the notch periodogram onto a VLSI architecture consisting mainly of a highly pipelined notch processor and two FFT processors. Second, without degrading the excellent performance of ANPA, the notch periodogram can be simplified and approximated to provide further computational reduction and implementational simplicity 相似文献
60.