An O(k3·log(n/k)) algorithm for theconsecutive-k-out-of-n:F system

The fastest generally-recognized algorithms for computing the reliability of consecutive-k-out-of-n:F systems require O(n) time, for both the linear and circular systems. The authors' new algorithm requires O(k³·log(n/k)) time. The algorithm can be extended to yield an O(n·max{k³·log(n/k), log(n))} total time procedure for solving the combinatorial problem of counting the number of working states, with w working and n-w failed components, w=1,2,...,n     

1677 V, 5.7 m/spl Omega//spl middot/cm/sup 2/ 4H-SiC BJTs

This letter reports the development of a high-performance power 4H-SiC bipolar junction transistor (BJT) with, simultaneously, a high blocking voltage and a low specific on-resistance (R/spl I.bar//sub ON/). A single BJT cell with an active area of 0.61 mm/sup 2/ achieves an open base collector-to-emitter blocking voltage (V/sub ceo/) of 1677 V and conducts up to 3.2 A at a forward voltage drop of V/sub CE/=3.0 V, corresponding to a low R/spl I.bar//sub ON/ of 5.7 m/spl Omega//spl middot/cm/sup 2/ up to Jc=525 A/cm/sup 2/ and a record high value of V/sub B//sup 2//R/sub SP/spl I.bar/ON/ of 493 MW/cm/sup 2/.     

10-kV, 123-m/spl Omega//spl middot/cm/sup 2/ 4H-SiC power DMOSFETs

10-kV, 123-m/spl Omega//spl middot/cm/sup 2/ power DMOSFETs in 4H-SiC are demonstrated. A 42% reduction in R/sub on,sp/, compared to a previously reported value, was achieved by using an 8 /spl times/ 10/sup 14/ cm/sup -3/ doped, 85-/spl mu/m-thick drift epilayer. An effective channel mobility of 22 cm/sup 2//Vs was measured from a test MOSFET. A specific on-resistance of 123 m/spl Omega//spl middot/cm/sup 2/ were measured with a gate bias of 18 V, which corresponds to an E/sub ox/ of 3 MV/cm. A leakage current of 197 /spl mu/A was measured at a drain bias of 10 kV from a 4H-SiC DMOSFET with an active area of 4.24 /spl times/ 10/sup -3/ cm/sup 2/. A switching time of 100 ns was measured in 4.6-kV, 1.3-A switching measurements. This shows that the 4H-SiC power DMOSFETS are ideal for high-voltage, high-speed switching applications.     

1330 V, 67 m/spl Omega//spl middot/cm/sup 2/ 4H-SiC(0001) RESURF MOSFET

Design and fabrication of 4H-SiC(0001) lateral MOSFETs with a two-zone reduced surface field structure have been investigated. The dose dependencies of experimental breakdown voltage show good agreement with simulation. Through the optimization of implant dose, high-temperature (1700/spl deg/C) annealing after ion implantation, and reduction of channel length, a breakdown voltage of 1330 V and a low on-resistance of 67 m/spl Omega//spl middot/cm/sup 2/ have been obtained. The figure-of-merit (V/sub B//sup 2//R/sub on/) of the present device reaches 26 MW/cm/sup 2/, being the best performance among lateral MOSFETs reported. The temperature dependence of static characteristics is also presented.     

930-V 170-m/spl Omega//spl middot/cm/sup 2/ lateral two-zone RESURF MOSFETs in 4H-SiC with NO annealing

The first lateral two-zone reduced surface field MOSFETs in 4H-SiC with NO annealing are reported. Interface properties of 4H-SiC-SiO/sub 2/ are improved, with inversion layer field-effect mobility increased to 25 cm/sup 2//V/spl middot/s, five times higher than that of dry reoxidation process, and with channel resistance significantly reduced. Devices are normally off with low leakage current. Threshold voltage is around 3 V. Blocking voltage of 930 V and specific on-resistance of 170 m/spl Omega//spl middot/cm/sup 2/ were obtained. Large-area devices with multifinger geometry are also demonstrated with scaled-up current. The output characteristics exhibit excellent linear and saturation regions.     

4H-SiC power bipolar junction transistor with a very low specific ON-resistance of 2.9 m/spl Omega//spl middot/cm/sup 2/

This letter reports a newly achieved best result on the specific ON-resistance (R/sub SP/spl I.bar/ON/) of power 4H-SiC bipolar junction transistors (BJTs). A 4H-SiC BJT based on a 12-/spl mu/m drift layer shows a record-low specific-ON resistance of only 2.9 m/spl Omega//spl middot/cm/sup 2/, with an open-base collector-to-emitter blocking voltage (V/sub ceo/) of 757 V, and a current gain of 18.8. The active area of this 4H-SiC BJT is 0.61 mm/sup 2/, and it has a fully interdigitated design. This high-performance 4H-SiC BJT conducts up to 5.24 A at a forward voltage drop of V/sub CE/=2.5 V, corresponding to a low R/sub SP-ON/ of 2.9 m/spl Omega//spl middot/cm/sup 2/ up to J/sub c/=859 A/cm/sup 2/. This is the lowest specific ON-resistance ever reported for high-power 4H-SiC BJTs.     

A 4.15 kV 9.07-m/spl Omega//spl middot/cm/sup 2/ 4H-SiC Schottky-barrier diode using Mo contact annealed at high temperature

In this letter, we report the fabrication of high-voltage and low-loss 4H-SiC Schottky-barrier diodes (SBDs) with a performance close to the theoretical limit using a Mo contact annealed at high-temperature. High-temperature annealing for the Mo contact was found to be effective in controlling the Schottky-barrier height at 1.2-1.3 eV without degradation of n-factor and reverse characteristics. We successfully obtained a 1-mm/sup 2/ Mo-4H-SiC SBD with a breakdown voltage (V/sub b/) of 4.15 kV and a specific on resistance (R/sub on/) of 9.07 m/spl Omega//spl middot/cm/sup 2/, achieving a best V/sub b//sup 2//R/sub on/ value of 1898 MW/cm/sup 2/. We also obtained a 9-mm/sup 2/ Mo-4H-SiC SBD with V/sub b/ of 4.40 kV and R/sub on/ of 12.20 m/spl Omega//spl middot/cm/sup 2/.     

An O(n·(log2(n))2) algorithm forcomputing the reliability of k-out-of-n:G and k-to-l-out-of-n:G systems

This paper presents the RAFFT-GFP (Recursively Applied Fast Fourier Transform for Generator Function Products) algorithm as a computationally superior algorithm for expressing and computing the reliability of k-out-of-n:G and k-to-l-out-of-n:G systems using the fast Fourier transform. Originally suggested by Barlow and Heidtmann (1984), generating functions provide a clear, concise method for computing the reliabilities of such systems. By recursively applying the FFT to computing generator function products, the RAFFT-GFP achieves an overall asymptotic computational complexity of O(n·(log₂(n)) ²) for computing system reliability. Algebraic manipulations suggested by Upadhyaya and Pham (1993) are reformulated in the context of generator functions to reduce the number of computations. The number of computations and the CPU time are used to compare the performance of the RAFFT-GFP algorithm to the best found in the literature. Due to larger overheads required, the RAFFT-GFP algorithm is superior for problem sizes larger than about 4000 components, in terms of both computation and CPU time for the examples studied in this paper. Lastly, studies of very large systems with unequal reliabilities indicate that the binomial distribution gives a good approximation for generating function coefficients, allowing algebraic solutions for system reliability     

On the filtering problem for stationary random /spl Zopf//sup 2/-fields

It is shown that whenever a stationary random field (Z/sub n,m/)/sub n,m/spl isin/z/ is given by a Borel function f:/spl Ropf//sup z/ /spl times/ /spl Ropf//sup z/ /spl rarr/ /spl Ropf/ of two stationary processes (X/sub n/)/sub n/spl isin/z/ and (Y/sub m/)/sub m/spl isin/z/ i.e., then (Z/sub n, m/) = (f((X/sub n+k/)/sub k/spl epsi/z/, (Y/sub m + /spl lscr// )/sub /spl lscr/ /spl epsi/z/)) under a mild first coordinate univalence assumption on f, the process (X/sub n/)/sub n/spl isin/z/ is measurable with respect to (Z/sub n,m/)/sub n,m/spl epsi/z/ whenever the process (Y/sub m/)/sub m/spl isin/z/ is ergodic. The notion of universal filtering property of an ergodic stationary process is introduced, and then using ergodic theory methods it is shown that an ergodic stationary process has this property if and only if the centralizer of the dynamical system canonically associated with the process does not contain a nontrivial compact subgroup.     

Survey of reliability studies of consecutive-k-out-of-n:F andrelated systems

The consecutive-k-out-of-n:F and related systems have caught the attention of many researchers since the early 1980s. The studies of these systems lead to better understanding of the reliability of general series systems, In computation and structure. This paper is mainly a chronological survey of computing the reliability of these systems     

Efficient amplification using the /sup 4/F/sub 3/2//spl rarr//sup 4/I/sub 9/2/ transition in Nd-doped silica fiber

Amplification characteristics of the three-level /sup 4/F/sub 3/2//spl rarr//sup 4/I/sub 9/2/ transition in Nd-doped silica glass fiber are investigated under strong signal saturation and high pump power (150 mW). Aluminum codoped Nd-silica fibers exhibit strong superfluorescent behavior in the four-level /sup 4/F/sub 3/2//spl rarr//sup 4/I/sub 11/2/ transition which limits the optical conversion efficiency into the three-level transition. Ge-doped silica fibers do not exhibit this limitation and can efficiently amplify in the three-level transition with current laser-diode pump technology.     

Maximum minimal distance partitioning of the /spl Zopf//sup 2/ lattice

We study the problem of dividing the /spl Zopf//sup 2/ lattice into partitions so that minimal intra-partition distance between the points is maximized. We show that this problem is analogous to the problem of sphere packing. An upper bound on the achievable intra-partition distances for a given number of partitions follows naturally from this observation, since the optimal sphere packing in two dimensions is achieved by the hexagonal lattice. Specific instances of this problem, when the number of partitions is 2/sup m/, were treated in trellis-coded modulation (TCM) code design by Ungerboeck (1982) and others. It is seen that methods previously used for set partitioning in TCM code design are asymptotically suboptimal as the number of partitions increases. We propose an algorithm for solving the /spl Zopf//sup 2/ lattice partitioning problem for an arbitrary number of partitions.     

The FT/sup /spl Lambda//-FR/sup /spl Lambda// AWG network: a practical single-hop metro WDM network for efficient uni- and multicasting

Single-hop wavelength-division-multiplexed (WDM) networks with a central passive star coupler (PSC), as well as single-hop networks with a central arrayed-waveguide grating (AWG) and a single transceiver at each node, have been extensively studied as solutions for the quickly increasing amounts of unicast and multicast traffic in the metropolitan area. The main bottlenecks of these networks are the lack of spatial wavelength reuse in the studied PSC-based networks and the single transceiver in the studied AWG-based metro WDM networks. This paper describes the development and evaluation of the FT/sup /spl Lambda//-FR/sup /spl Lambda// AWG network, which is based on a central AWG and has arrays of fixed-tuned transmitters and receivers at each node. Transceiver arrays are a mature technology, making the proposed network practical. In addition, the transmitter arrays allow for high-speed signaling over the AWG while the receiver arrays relieve the receiver bottleneck arising from multicasting in conjunction with spatial wavelength reuse on the AWG. The results from probabilistic analysis and simulation reported here indicate that the FT/sup /spl Lambda//-FR/sup /spl Lambda// AWG network gives particularly good throughput-delay performance for a mix of unicast and multicast traffic.     

Demonstration of 1789 V, 6.68 m/spl Omega/ /spl middot/ cm/sup 2/ 4H-SiC merged-PiN-Schottky diodes

The design, fabrication and characterisation of a high performance 4H-SiC diode of 1789 V-6.6 A with a low differential specific-on resistance (R/sub SP/spl I.bar/ON/) of 6.68 m/spl Omega/ /spl middot/ cm/sup 2/, based on a 10.3 /spl mu/m 4H-SiC blocking layer doped to 6.6/spl times/10/sup 15/ cm/sup -3/, is reported. The corresponding figure-of-merit of V/sub B//sup 2//R/sub SP/spl I.bar/ON/ for this diode is 479 MW/cm/sup 2/, which substantially surpasses previous records for all other MPS diodes.     

Reliability of 2-dimensional consecutive-k-out-of-n:F systems

The authors derive lower and upper reliability bounds for the two-dimensional consecutive k-out-of-n:F system (Salvia Lasher, 1990) with independent, but not necessarily identically distributed, components. A Weibull limit theory is proven for system time-to-failure for i.i.d. components     

All-optical signal processing using /spl chi//sup (2)/ nonlinearities in guided-wave devices

The authors present a review of all-optical signal-processing technologies based on /spl chi//sup (2)/ nonlinear interactions in guided-wave devices and their applications for telecommunication. In this study, the main focus is on three-wave interactions in annealed proton-exchanged periodically poled lithium niobate waveguides due to their suitable properties with respect to nonlinear mixing efficiency, propagation loss, and ease of fabrication. These devices allow the implementation of advanced all-optical signal-processing functions for next-generation networks with signal bandwidths beyond 1 THz. In this paper, integrated structures that will allow for improvements of current signal-processing functions as well as the implementation of novel device concepts are also presented.     

Normal basis multiplication algorithm for GF(2/sup n/)

A normal basis multiplication algorithm is presented. Its complexity depends on the multiplicative order of the normal element.     

Additive bit-serial algorithm for discrete logarithm modulo 2/sup k/

A novel algorithm for computing the discrete logarithm modulo 2/sup k/ that is suitable for fast software or hardware implementation is described. The chosen preferred implementation is based on a linear-time multiplier-less method and has a critical path of less than k modulo 2/sup k/ shift-and-add operations.     

Recursive formulas for the reliability of multi-state consecutive-k-out-of-n:G systems

In this paper, we provide an algorithm for evaluating the system state distribution for any multi-state consecutive-k-out-of-n:G system including the decreasing multi-state G system, the increasing multi-state G system, and other G systems. We evaluated our proposed algorithms in terms of the orders of computation time, and memory requirement. Furthermore, we conducted a numerical experiment to determine the actual computation time. Our proposed algorithm is more effective for systems with a large n.     

An efficient VLSI design for a residue to binary converter for general balance moduli (2/sup n/-3,2/sup n/+1,2/sup n/-1,2/sup n/+3)

In this paper, we present a new four-moduli set (2/sup n/-3,2/sup n/+1,2/sup n/-1,2/sup n/+3) and an efficient residue to binary (R/B) converter design. The merits of the proposed four-moduli set include 1) larger dynamic range; 2) higher degree of parallelism for conversion; 3) balanced bit-width for internal RNS arithmetic operations; and 4) flexible moduli set selection. According to the relation between the proposed moduli, the divide-and-conquer technique is used to design a two-level converter architecture which has lower hardware cost and shorter critical delay. For the R/B converter designed with 12-b (n=3), our architecture has about 47% saving in hardware cost and 40% saving in critical delay compared to the last work.