Browsing by Author "Wang, TY"

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A 10-Gb/s laser diode driver in 0.35 mu m BiCMOS technology
(2005)
Wang, TY
;
Chen, WZ
;
Tsai, CM
;
Huang, LR
;
Li, DU
This paper describes the design of a 10Gb/s laser diode (LD) driver in a 0.35 mu m SiGe BiCMOS technology. The LD driver delivers a biased current up to 60 mA, and a modulation current ranges from 40 mA to 100 mA. High speed operation as well as high current driving capability are achieved by means of push-pull current switching scheme. In addition, negative Miller capacitor compensation technique is adopted to enhance the signal bandwidth. The output swing of the predriver is dynamically adjustable to compromise between operating speed and overshoot. Both the modulation and biased currents are derived from a bandgap reference source. The measured rise/fall time is 47ps, and timing jitter is 22.2ps(p-p). The eye diagrams meet the specifications defined by SONET OC-192 and 10G Ethernet eye mask. Operating under 3.3V/7V supply, the total power consumption is 1.38W. Chip size is 1430 x 940 mu m(2).
Asymptotic performance analysis for minimum-hamming-distance fusion
(2005)
Chen, PN
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Wang, TY
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Han, YSS
;
Varshney, PK
;
Yao, C
Distributed (M-ary) detection and fault-tolerance have been considered as two fundamental functions in the context of large-scale sensor networks. Distributed multiclass classification fusion using error correcting codes (DCFECC) has been proposed to provide good fault-tolerance capability in wireless sensor networks. Minimum Hamming distance fusion is an essential part of the DCFECC approach. In this paper, we study the asymptotic performance of minimum Hamming distance fusion for both fault-free and faulty situations when the number of sensors tends to infinity. We conclude that the error probability vanishes asymptotically as long as the minimum Hamming distance d(min) of the DCFECC code approaches infinity, and the probabilities of correct local classification for all hypotheses are greater than one half. In case d(min)/2, normalized by the number of sensors, can be made larger than the largest local classification error, an explicit expression for the error exponent of the DCFECC system in terms of the Kullback-Leibler divergence can be established. A converse where the DCFECC decoding error is bounded away from zero is also addressed.
Distributed fault-tolerant classification in wireless sensor networks
(2005-04-01)
Wang, TY
;
Han, YSS
;
Varshney, PK
;
Chen, PN
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電信工程研究所
Fault-tolerance and data fusion have been considered as two fundamental functions in wireless sensor networks. In this paper, we propose a novel approach for distributed multiclass classification using a fault-tolerant fusion rule for wireless sensor networks. Binary decisions from local sensors, possibly in the presence of faults, are forwarded to the fusion center that determines the final classification result. Classification fusion in our approach is implemented via error correcting codes to incorporate fault-tolerance capability. This new approach not only provides an improved fault-tolerance capability but also reduces computation time and memory requirements at the fusion center. Code matrix design is essential for the design of such systems. Two efficient code matrix design algorithms are proposed in this paper. The relative merits of both algorithms are also studied. We also develop sufficient conditions for asymptotic detection of the correct hypothesis by the proposed approach. Performance evaluation of the proposed approach in the presence of faults is provided. These results show significant improvement in fault-tolerance capability as compared with conventional parallel fusion networks.
Maximum entropy analysis to the N policy M/G/1 queueing system with server breakdowns and general startup times
(2005-06-06)
Wang, KH
;
Wang, TY
;
Pearn, WL
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工業工程與管理學系
;
Department of Industrial Engineering and Management
We study a single removable and unreliable server in the N policy M/G/1 queueing system with general startup times where arrivals form a Poisson process and service times are generally distributed. When N customers are accumulated in the system, the server is immediately turned on but is temporarily unavailable to the waiting customers. He needs a startup time before providing service until the system becomes empty. The server is subject to breakdowns according to a Poisson process and his repair time obeys an arbitrary distribution. We use maximum entropy principle to derive the approximate formulas for the steady-state probability distributions of the queue length. We perform a comparative analysis between the approximate results with established exact results for various distributions, such as exponential (M), fc-stage Erlang (E-k), and deterministic (D). We demonstrate that the maximum entropy approach is accurate enough for practical purposes and is a useful method for solving complex queueing systems. (c) 2004 Published by Elsevier Inc.
Maximum likelihood estimates and confidence intervals of an M/M/R queue with heterogeneous servers
(2006-05-01)
Wang, TY
;
Ke, JC
;
Wang, KH
;
Ho, SC
;
工業工程與管理學系
This paper studies maximum likelihood estimates as well as confidence intervals of an M/M/R queue with heterogeneous servers under steady-state conditions. We derive the maximum likelihood estimates of the mean arrival rate and the three unequal mean service rates for an M/M/3 queue with heterogeneous servers, and then extend the results to an M/M/R queue with heterogeneous servers. We also develop the confidence interval formula for the parameter rho, the probability of empty system P-0, and the expected number of customers in the system E[N], of an M/M/R queue with heterogeneous servers.
Nano-carbon nitride synthesis from a bio-molecular target for ion beam sputtering at low temperature
(1999-03-01)
Wu, JJ
;
Lu, TR
;
Wu, CT
;
Wang, TY
;
Chen, LC
Nano-crystalline carbon nitride has been successfully synthesized at a temperature below 100 degrees C from an adenine(C5N5H5) target sputtered by an Ar ion beam. Because adenine possesses a ring structure similar to the hypothetical beta-C3N4 phase, the use of this bio-molecular compound as the target is believed to reduce the energy barrier of carbon-nitride growth. The effect of Ar ion-sputtering voltage on the film growth and the effect of extra-N-atom incorporation on the carbon-nitride film growth are examined in this study. Only a carbon film is formed with an ion energy of 500 V. For the ion-beam energy above 750 V, carbon nitride films are deposited, and there is some hydrogen incorporation in the films. The N/C composition ratio in the films could reach 1:1 and is independent on the ion beam voltage. The nitrogen is bonded with carbon within the films, as determined by the IR and XPS measurements. However, the films deposited at a higher ion voltage could possess some original functional groups of adenine. A strong and broad peak at a d-spacing of 0.32 nm, comparable to the calculated d-spacing of the beta-C3N4(110), is observed in the XRD spectra of the carbon nitride films. The TEM results indicated that the film contained nano-crystalline grains. Several d values are also in good agreement with those of adenine and the calculated values of beta-C3N4. The C/N ratios of the films are still kept at almost 1:1 with N atoms added during deposition. The XRD spectra and IR spectra of these films are all similar to the film deposited without nitrogen source. (C) 1999 Elsevier Science S.A. All rights reserved.