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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 28, Issue 10, 7 May 1992

Volumes & issues:

Volume 28, Issue 10

7 May 1992

Ultrahigh-speed driverless MQW intensity modulator, and 20 Gbit/s, 100 km transmission experiments
  • Author(s): T. Kataoka ; Y. Miyamoto ; K. Hagimoto ; K. Wakita ; I. Kotaka
  • Source: Electronics Letters, Volume 28, Issue 10, p. 897 –898
  • DOI:  10.1049/el:19920569
  • Type: Article
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  • p. 897 –898 (2)
    An InGaAs/InAlAs MQW modulator with the low voltage of 1.5 V for 10 dB extinction ratio and 16 GHz bandwidth has been developed. This ultrahigh-speed modulator enables the modulator driver to be eliminated from the transmitter. 100 km transmission experiments have been carried out using either a 1 V peak to peak output monolithic-IC-driven modulator at 15 Gbit/s or a 2 V peak to peak output multiplexer-driven modulator at 20 Gbit/s. This is the first report on multigigabit operation of MQW modulators to the authors' knowledge.
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Differential phase noise distribution of Rayleigh faded DPSK signal with selection diversity
  • Author(s): F. Adachi  and  M. Sawahashi
  • Source: Electronics Letters, Volume 28, Issue 10, p. 898 –900
  • DOI:  10.1049/el:19920570
  • Type: Article
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  • p. 898 –900 (3)
    Closed-form expressions for the distribution of differential phase noise due to additive white Gaussian noise (AWGN) are derived for predetection selection diversity with independent, equal power very slow Rayleigh fading signals. Also investigated are the effects of fading correlation and unequal powers between diversity antennas on practical two-branch diversity reception. The derived phase distribution is used to calculate the average symbol error rate of 8DPSK as an example.
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Fibre diameter estimation based on guided acoustic wave Brillouin scattering
Multiple channel selfrouting crossbar switch
Side-emitting GaAs/AlGaAs SQW LEDs showing wide spectrum using shadow masked growth
  • Author(s): G. Vermeire ; L. Buydens ; P. Van Daele ; P. Demeester
  • Source: Electronics Letters, Volume 28, Issue 10, p. 903 –905
  • DOI:  10.1049/el:19920573
  • Type: Article
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  • p. 903 –905 (3)
    Side-emitting LEDs are proposed showing a wide optical spectrum. The LEDs were fabricated using a special growth technique called shadow masked growth (SMG). The width of the window in the shadow mask was gradually changed along the LED stripe direction and therefore resulted in a continuous variation of the layer thickness. The combination with a quantum well active region results in a continuous variation in bandgap and emission wavelength. These different spectra add up at one side of the LED offering a broad spectrum. By decreasing the width of the window, starting from 100 μm, GaAs/AIGaAs GRINSCH SQW LEDs have been realised with spectral widths up to 63 nm and very small spectral ripple.
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Low-threshold 630 nm-band AlGaInP multiquantum-well laser diodes grown on misoriented substrates
  • Author(s): M. Shono ; H. Hamada ; S. Honda ; R. Hiroyama ; K. Yodoshi ; T. Yamaguchi
  • Source: Electronics Letters, Volume 28, Issue 10, p. 905 –906
  • DOI:  10.1049/el:19920574
  • Type: Article
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  • p. 905 –906 (2)
    Low-threshold AlGaInP (λL = 635.6 nm) multiquantum-well laser diodes have been successfully fabricated by MOCVD using (100) GaAs substrates with a misorientation of 7° towards the (011) direction. A threshold current of 57 mA at 20°C, the lowest value ever reported for 630 nm-band AIGalnP lasers, has been obtained using transverse-mode stabilised laser diodes (stripe width: 5 μm, cavity length: 350 μm).
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Solving sorting and related problems by quadratic perceptrons
Picosecond square pulse generation using nonlinear fibre loop mirror
Longitudinal component of aperture electric field in weakly-excited broadwall slot
Fabrication of MSM photoconductor on porous Si using micromachined silicon mask
  • Author(s): L.Z. Yu  and  C.R. Wie
  • Source: Electronics Letters, Volume 28, Issue 10, p. 911 –913
  • DOI:  10.1049/el:19920578
  • Type: Article
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  • p. 911 –913 (3)
    An MSM photoconductive detector has been fabricated from porous silicon using a micromachined silicon mask instead of photolithography. This approach allows damage to porous silicon that can be caused by chemical processing to be avoided. The interdigitated pattern of the silicon mask with a finger spacing of approximately 150 μm and finger width of 50 μm was made using silicon micromachining. The fabricated MSM porous silicon photoconductive detector, which exhibits responsivities of better than 0.5 A/W at the wavelength of the He-Ne laser (6280 Å) and a dark current of 950nA at 10V, is very promising as an optoelectronic device.
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Rigorous analysis of scattering by partial height magnetised ferrite posts in rectangular waveguides
Negative differential resistance of GaAs/AlxGa1−xAs multiquantum well structures under high power photoexcitation: structure optimisation for an oscillator
  • Author(s): S. Goswami ; L. Davis ; S. Hong ; J. Singh ; P.K. Bhattacharya ; G.I. Haddad
  • Source: Electronics Letters, Volume 28, Issue 10, p. 915 –916
  • DOI:  10.1049/el:19920580
  • Type: Article
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  • p. 915 –916 (2)
    A study is presented of the photocurrent behaviour of pin diodes having GaAs/AlxGa1−xAs MQW absorption regions for varying incident power, incident wavelength and barrier height, given by the Al fraction x. Optimum results for applications in high power oscillators are expected to be obtained for 0.1 < x < 0.2. The performance characteristics of optically controlled oscillators are estimated for a diode with MQW having Al0.15Ga0.85As barriers.
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Accurate low-power CMOS autozeroed comparator
  • Author(s): B. Baggini ; F. Maloberti ; G. Palmisano
  • Source: Electronics Letters, Volume 28, Issue 10, p. 916 –918
  • DOI:  10.1049/el:19920581
  • Type: Article
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  • p. 916 –918 (3)
    A low-power CMOS autozeroed comparator suitable for high-frequency A/D convertors is discussed. The use of a source follower in the autozeroed inverter stage allows the circuit to provide an optimum tradeoff between speed, gain and power dissipation. Relationships are given that relate the time response, both in the autozeroing and comparating phase, to the circuit parameters. An experimental prototype, fabricated with a 2μm CMOS process, is also presented.
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High speed class AB voltage-current convertor with improved accuracy
Silicon based fibre pigtailed 1×16 power splitter
Very fast accurate square-root algorithm for use with gradient edge operators
  • Author(s): H.B. Mitchell
  • Source: Electronics Letters, Volume 28, Issue 10, p. 922 –923
  • DOI:  10.1049/el:19920584
  • Type: Article
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  • p. 922 –923 (2)
    Commonly used gradient edge operators such as the Sobel, Prewitt and Roberts operators all required a square root operation; this is, however, computationally intensive and, consequently, simple but very inaccurate approximations are often used instead. The Letter describes a new square root algorithm specifically designed for use with these edge operators. The result is a very simple, fast and extremely accurate algorithm.
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Distribution of phase angle between two Rayleigh vectors perturbed by Gaussian noise
  • Author(s): F. Adachi  and  T.T. Tjhung
  • Source: Electronics Letters, Volume 28, Issue 10, p. 923 –925
  • DOI:  10.1049/el:19920585
  • Type: Article
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  • p. 923 –925 (3)
    Two general, closed form expressions for the distribution of the phase angle between two vectors in fast Rayleigh fading and Gaussian noise are derived. These general expressions include the effect of fading as well as noise correlation and, in special cases, reduce to several previously published formulas. The convenience when applying these new formulas to evaluate the error performance of DPSK and FSK. systems is highlighted.
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Low programming voltage floating gate analogue memory cells in standard VLSI CMOS technology
General linear composite-MOSFET theory and applications
Error pattern addition for cell synchronisation in ATM systems
  • Author(s): A.F. De Sousa  and  A.M. De Oliveira Duarte
  • Source: Electronics Letters, Volume 28, Issue 10, p. 929 –930
  • DOI:  10.1049/el:19920588
  • Type: Article
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  • p. 929 –930 (2)
    The use of cyclic codes for cell header codification in ATM transmission systems constrains the performance of cell synchronisation. Positions near the beginning of each cell are critical because the probability of false header detection is maximised when using a bit-by-bit search routine. To solve this problem, modifications to the standard operations of encoding and decoding by means of a codeword error pattern addition are proposed. The new implementations exhibit the same degree of complexity of the original ones. Improvements in the synchronisation performances are illustrated by simulation.
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Generation of soliton pulse train in optical fibre using two CW singlemode diode lasers
  • Author(s): S.V. Chernikov ; P.V. Mamyshev ; E.M. Dianov ; J.R. Taylor
  • Source: Electronics Letters, Volume 28, Issue 10, p. 931 –932
  • DOI:  10.1049/el:19920589
  • Type: Article
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  • p. 931 –932 (2)
    A train of fundamental solitons at 1.53 μm has been generated, with pulse durations of 1.5–3.0 ps, at a repetition rate in the range 80–130GHz from the output of two CW single mode DFB lasers amplified in an Er-doped fibre. The transformation of the beat signal into a soliton train resulted from nonlinear propagation of the signal in a special fibre with dispersion decreasing along the length.
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Normal incidence infra-red absorption from intersub-band transitions in p-type GaInAs/AIInAs quantum wells
10 Gbit/s optical demultiplexing and switching by sinusoidally driven InGaAsP electroabsorption modulators
Quantum well laser with single InAs monolayer in active region
  • Author(s): M.L. Dotor ; P. Huertas ; J. Meléndez ; A. Mazuelas ; M. Garriga ; D. Golmayo ; F. Briones
  • Source: Electronics Letters, Volume 28, Issue 10, p. 935 –937
  • DOI:  10.1049/el:19920592
  • Type: Article
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  • p. 935 –937 (3)
    A single monolayer thick InAs quantum well laser structure has been grown at low substrate temperature by atomic layer molecular beam epitaxy (ALMBE). The laser has an emission wavelength of ̃884nm and a threshold current density of 1.97kA/cm2 at room temperature. This value is lower than values obtained for other monolayer thick quantum well lasers, and it demonstrates the device quality of epitaxial layers grown at 350°C by ALMBE.
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In0.1Ga0.9As/GaAs/AIAs pseudomorphic resonant tunnelling diodes integrated with airbridge
  • Author(s): E. Lheurette ; B. Grimbert ; M. François ; P. Tilmant ; D. Lippens ; J. Nagle ; B. Vinter
  • Source: Electronics Letters, Volume 28, Issue 10, p. 937 –938
  • DOI:  10.1049/el:19920593
  • Type: Article
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  • p. 937 –938 (2)
    The fabrication of an airbridged low parasitic resonant tunnelling diode is described. The devices were fabricated from strained In0.1Ga0.9As/GaAs/AlAs layers. They yielded excellent DC characteristics with simultaneously high peak-to-valley current ratios of 7:1 and peak current of 50kA/cm2 at 300K. RF measurements up to 40GHz showed that the total parasitic capacitance was 0.013 pF.
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Fast vector quantisation using cache codebook
Robust and fast failure detection and prediction for fault-tolerant communication network
Large blue shifts induced by Stark effect in asymmetric coupled quantum well
Separation of differential propagation phase and differential backscatter phase in polarisation diversity radar
Radar estimation of apparent canting angle in raindrops
Room-temperature operation of MOCVD-grown GaInAs/InP strained-layer multiquantum well lasers in 1.8 μm range
  • Author(s): S. Forouhar ; A. Larsson ; A. Ksendzov ; R.J. Lang ; N. Tothill ; M.D. Scott
  • Source: Electronics Letters, Volume 28, Issue 10, p. 945 –947
  • DOI:  10.1049/el:19920599
  • Type: Article
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  • p. 945 –947 (3)
    The first successful room-temperature pulsed operation is reported of InGaAs strained layer multiquantum well (SLMQW) injection lasers grown by MOVPE on InP substrates in the 1.8 μm range. The threshold current density and the external differential quantum efficiency of the 10 μm wide ridge waveguide lasers were 2.5 kA/cm2 (cavity length = 1mm) and 5% (cavity length = 400μm), respectively. Broad-area lasers, 100 μm wide and 1 mm long, had a reverse leakage current of less than 10 μA at − 1V indicating high quality of the epitaxial layers.
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Cascade perceptron
Efficient multilevel coding scheme for video transmission
  • Author(s): H. Gharavi
  • Source: Electronics Letters, Volume 28, Issue 10, p. 949 –951
  • DOI:  10.1049/el:19920601
  • Type: Article
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  • p. 949 –951 (3)
    A coding scheme comprising interframe DPCM, sub-band coding, and the discrete cosine transform is presented. The scheme has been expanded to include a multilevel video transmission which has resulted in a hybrid DPCM/DCT coding structure at its lowest level. This property is then used to transmit high quality video with full compatibility to existing hybrid based coding standards such as H.261 for videophone. In addition, for each level to be coded independently, a layer called the residual layer is generated at the lower level. Simulation results are presented for a two-level video transmission where the first and second levels are coded at the rates of 64kbit/s and 4Mbit/s, respectively
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Comment: Pulses satisfying the Nyquist criterion
Reply: Pulses satisfying the Nyquist criterion
Root signal sets of morphological filters
  • Author(s): Q. Wang ; M. Gabbouj ; Y. Neuvo
  • Source: Electronics Letters, Volume 28, Issue 10, p. 952 –953
  • DOI:  10.1049/el:19920604
  • Type: Article
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  • p. 952 –953 (2)
    The theory of state description for the binary root signal set of morphological filters is presented. Some properties of root signals are discussed. For a signal of length n and structuring element of size k, the number of binary roots for morphological opening and closing is represented by the difference equation R(n + 1) = 2R(n) − R(n − 1) + R(n − k). For open-closing and clos-opening, the difference equation is R(n + 1) = R(n) + R(n + 1 − k).
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Dispersion compensation in 450 km transmission system employing standard fibre
  • Author(s): A.D. Ellis ; S.J. Pycock ; D.A. Cleland ; C.H.F. Sturrock
  • Source: Electronics Letters, Volume 28, Issue 10, p. 954 –955
  • DOI:  10.1049/el:19920605
  • Type: Article
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  • p. 954 –955 (2)
    It is demonstrated that by directly prechirping an externally modulated DFB laser at the clock frequency, transmission of a 5 Gbit/s NRZ signal beyond the dispersion limit of 300 km for step index fibre is possible. In particular, operation of the system over 450 km of fibre, representing a total dispersion of 7.2 ns/nm, and the use of time resolved chirp measurements for the system optimisation, are reported.
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2 V drive-voltage switching operation in 1.55 μm GaInAs/InP MQW intersections waveguide optical switch
Analogue voltage multiplier/divider with stabilised scale factor
Physical interpretation of reduction of soliton interaction forces by bandwidth limited amplification
  • Author(s): M. Nakazawa  and  H. Kubota
  • Source: Electronics Letters, Volume 28, Issue 10, p. 958 –960
  • DOI:  10.1049/el:19920608
  • Type: Article
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  • p. 958 –960 (3)
    It is shown that the reduction in soliton interaction by bandwidth limited amplification is entirely due to adiabatic narrowing caused by excess gain, in which the input soliton pulse achieves a narrower steady-state pulse. The bandwidth limitation is used to generate a narrow steady-state soliton by stopping the adiabatic narrowing, but does not reduce the interaction forces by directly changing the soliton spectrum. When the asymptotic soliton solution is used as an input, there is no reduction in the soliton interaction.
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Three-line microstrip directional coupler for microwave switch matrix
Simple sequence detector for coded (1-D) partial response channel
FM efficiency and spectral linewidth in two-active-section DBR laser
Petri nets for classification
  • Author(s): M. Nathan  and  S.E. Tavares
  • Source: Electronics Letters, Volume 28, Issue 10, p. 965 –966
  • DOI:  10.1049/el:19920612
  • Type: Article
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  • p. 965 –966 (2)
    Research in neural networks has reached an intense state of activity with growing interest in practical and commercial applications. Neural networks provide a solution for tasks which require a huge processing capacity, by using a large number of simple elements operating in parallel. One such task is pattern classification. In this Letter we discuss Petri nets for classification, which use the same basic principles as neural networks. Because Petri nets also have appealing simplicity in expressing existing interactions in concurrent systems we have found them suitable for modelling or emulating neural networks.
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Robust finite element solution for three-dimensional scattering
Measurement and simulation of floating substrate effects on the intrinsic gate capacitance characteristics of SOI n-MOSFETs
Integrated 1 V thermal shutdown circuit
Runlength limited codes for random and burst error correction
Erratum: Implementation of numerically robust fast recursive least squares adaptive filters using interval arithmetic

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