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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 26, Issue 16, 2 August 1990

Volumes & issues:

Volume 26, Issue 16

2 August 1990

Six-bit DPCM video signal processing and implementation using systolic arrays
  • Author(s): M.K. Ibrahim  and  A. Aggoun
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1225 –1227
  • DOI:  10.1049/el:19900789
  • Type: Article
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  • p. 1225 –1227 (3)
    A novel approach to increase the speed and reduce the hardware requirement of 2-D systolic convolvers for real-time video signal/image processing is proposed. This is achieved by coding video signals/images more efficiently using six-bit I-D DPCM coding. It is shown that using six-bit differential pulse-code modulation processing results in a 57% improvement in speed and a significant saving in the cost of 2-D systolic convolvers. The effect of quantisation errors on DPCM image convolution is also presented.
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Waiting time jitter reduction by fill locking
Improved feed-system for a printed antenna composed of strip dipoles and slots
Microwave power limiter based on high-Tc superconductive film
  • Author(s): M.M. Gaidukov ; S.G. Kolesov ; L. Kowalewicz ; A.B. Kozyrev ; O.G. Vendik
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1229 –1231
  • DOI:  10.1049/el:19900792
  • Type: Article
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  • p. 1229 –1231 (3)
    A power limiter is designed with two resonant diaphragms included in an X-range rectangular waveguide. The cross strips made of high-Tc superconductive films placed in the centre of diaphragms can be in superconducting or normal states. The film state is controlled by the microwave power. The S-N transition in the strips causes a change of the transmitted wave attenuation from 0.5 to 25 dB.
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Improved InP/InGaAs/InP pin detector response using a transparent conductor contact
  • Author(s): J. Lee Russell ; F. Kellert ; E. Ehlers ; D. Monahan
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1231 –1232
  • DOI:  10.1049/el:19900793
  • Type: Article
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  • p. 1231 –1232 (2)
    The elimination of the spatial variation in the frequency response of large area pin photodetectors is described using indium tin oxide as a transparent contact. The I/V, C/V, and relative frequency response characteristics are reported for devices fabricated with and without the indium tin oxide. The devices have active area diameters of 25.0 and 80.0μm. Responsivities were 0.53 and 0.61 A/W for photodetectors with and without the ITO contact, respectively.
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Minimal state space realisation of product factorable 2-D systems
Bit error probability of phase-coherent communication systems in the presence of noise and interference
Millimetre-wave second harmonic generation on a nonlinear transmission line
Skin effect losses of interconnect lines in frequency and time domain
  • Author(s): W. Wlodarczyk  and  V. Besch
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1237 –1238
  • DOI:  10.1049/el:19900797
  • Type: Article
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  • p. 1237 –1238 (2)
    The influence of the frequency-dependent resistive losses of interconnect lines on the propagation of very-high-speed digital pulses is investigated using different loss models. It is shown that, depending on the range of the frequency spectrum of digital pulses and/or the cross-sectional dimensions of an interconnect structure, the DC losses and losses caused by Wheeler's incremental inductance rule are to be extendedby broadband skin effect losses, to obtain a better prediction of thepulse deformation.
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Mode locking of a continuous wave neodymium doped fibre laser with a linear external cavity
Synthetis of single sets of 2n mutually orthogonal phase codes
Daugman's gabor transform as a simple generative back propagation network
  • Author(s): D. Cohen  and  J. Shawe-Taylor
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1241 –1243
  • DOI:  10.1049/el:19900800
  • Type: Article
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  • p. 1241 –1243 (3)
    Much work has been performed on learning mechanisms for neural networks. A particular area of interest has been the use of neural networks for image processing problems. Two important pieces of work in this area are unified. An architecture and learning scheme for neural networks called generative back propagation has been previously developed and a system for image compression and filtering based on 2-D Gabor transformations which used a neural network type architecture described. Daugman's procedure is exactly replicated. A procedure which used a four layer neural network as a two-layer generative back propagation network with half of the units. The GBP update rule is shown to perform the same change as Daugman's rule, but more efficiently.
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Two-section distributed feedback lasers for incoherent frequency-shift-keying transmission systems
130 Mbit/s (H4 rate) HDTV codec based on the DCT algorithm
  • Author(s): T. Kinoshita ; T. Nakahashi ; Y. Eto
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1245 –1246
  • DOI:  10.1049/el:19900802
  • Type: Article
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  • p. 1245 –1246 (2)
    The hardware implementation of a 130 Mbit/s (H4 rate) HDTV CODEC based on the DCT (discrete cosine transform) algorithm is studied for transmission in broadband ISDN (BISDN). The intrafield 2-dimensional DCT, nonlinear fixed bit quantisation of eight classes with switchable operation between y and Pr/Pb, and the four parallel signal processing possible by DCT are also implemented in the CODEC. Performance evaluation confirms that the developed CODEC has sufficient picture quality and is practical for HDTV distribution use.
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Low phase noise heterojunction bipolar transistor oscillator
  • Author(s): M. Ali Khatibzadeh  and  B. Bayraktaroglu
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1246 –1248
  • DOI:  10.1049/el:19900803
  • Type: Article
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  • p. 1246 –1248 (3)
    A low phase noise, heterojunction bipolar transistor (HBT) oscillator has been designed and fabricated for operation at X-band. The common emitter oscillator employs a high-Q dielectric resonator as the parallel feedback element between the base and collector terminals. Series capacitive feedback is used in the emitter to enhance the oscillator's negative output impedance. Single-sideband FM noise levels of −76dBc/Hz and −102dBc/Hz have been achieved at 1 kHz and 10kHz frequency offsets, respectively, for an 11.06GHz carrier frequency. This is one of the lowest phase noise levels ever reported for an X-band solid-state transistor oscillator.
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Process dependence of interface state generation due to irradiation and hot carrier stress in rapid thermally nitrided thin gate oxides
  • Author(s): A.B. Joshi ; G.Q. Lo ; D.K. Kwong
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1248 –1249
  • DOI:  10.1049/el:19900804
  • Type: Article
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  • p. 1248 –1249 (2)
    A study of the effects of nitridation time and temperature on the interface state generation in MOS devices with thin rapid thermally nitrided gate oxides is reported. A different process dependence was observed for interface state generation caused by X-ray irradiation and hot carrier stress. The discrepancy is explained using the structural changes at the interface during nitridation and some of the earlier defect generation models.
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Asymptotic solution for line source radiation from a curved perfectly conducting wedge
Open loop fibre optic gyroscope with phase shift nulling signal processing
Range determination in a multipath prone environment
Non-equally fractionally-spaced equalisers
Improved version of the inverse Chebyshev filter
  • Author(s): M. Lutovac  and  D. Rabrenović
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1256 –1257
  • DOI:  10.1049/el:19900809
  • Type: Article
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  • p. 1256 –1257 (2)
    The inverse Chebyshev function is formed by a transformation of a rational equiripple function defined by two polynomial Chebyshev functions of the same order. Since the transformation moves the finite complex zeros of the original rational function to the imaginary axis, its main imperfections, such as low selectivity and relatively large Q factors of the zeros, are eliminated. Extremely low pole-Q factors of the initial function are retained, providing a low sensitivity and a good group delay.
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Novel gate voltage ramping technique for the characterisation of metal-oxide-semiconductor capacitor charge trapping properties
  • Author(s): W. Ting ; G.Q. Lo ; D.L. Kwong
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1257 –1259
  • DOI:  10.1049/el:19900810
  • Type: Article
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  • p. 1257 –1259 (3)
    A novel technique is proposed to characterise the charge trapping properties of MOS capacitors by using the gate voltage ramping test. The parameter I=1−Ig(t)/Is(t + Δt) measured during gate voltage ramping reveals the dielectric charge trapping characteristics. Positive charge trapping before dielectric breakdown was observed using this technique. A comparison between I and flatband voltage shift, ΔVfb, indicates that I gives the same information as ΔVfb does at high stress fluences.
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Design criteria for video sampling rate conversion filters
Heterostructure bipolar transistor employing carbon-doped base grown with trimethyl-Ga and arsine
  • Author(s): T.Y. Kuo ; T.H. Chiu ; J.E. Cunningham ; K.W. Goossen ; C.G. Fonstad ; F. Ren
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1260 –1262
  • DOI:  10.1049/el:19900812
  • Type: Article
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  • p. 1260 –1262 (3)
    The investigation of an AlGaAs/GaAs HBT in in which a heavily carbon doped base is grown by chemical beam epitaxy using trimethyl-Ga is reported. A planar technique which reduces surface recombination has been employed for selectively contacting the base region. A base width of 1000 Å and a high doping level of 7 × 1019cm−3 is used. The sheet resistance of the base is less than 100Ω/□. This transistor has a maximum current gain of 25 at a current density of 1.3 × 103A/cm2.
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Optical domain frequency translation of a modulated optical carrier
Strained layer AlGaAs-GaAs-InGaAs real-space transferred electron devices
  • Author(s): M.E. Favaro ; J.J. Alwan ; R.P. Bryan ; L.M. Miller ; J.J. Coleman ; J. Kim ; C.M. Wayman
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1264 –1265
  • DOI:  10.1049/el:19900814
  • Type: Article
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  • p. 1264 –1265 (2)
    Experimental results of two AlGaAs-GaAs real-space transferred electron devices, the negative resistance field-effect transistor and charge-injection transistor, which incorporates a strained layer In0.22Ga0.78As channel are reported. The negative differential resistance in the drain circuit has a drain current peak-to-valley ratio of more than 1200 at room temperature.
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Calculating the upper and lower bounds on the capacity of two modified Hebbian trained Hopfield networks
New M-PSK trellis codes for fading channels
AMI-CPFSK heterodyne transmission experiment using a novel delay-line demodulation method
Efficient mode conversion in telecommunication fibre using externally written gratings
  • Author(s): K.O. Hill ; B. Malo ; K.A. Vineberg ; F. Bilodeau ; D.C. Johnson ; I. Skinner
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1270 –1272
  • DOI:  10.1049/el:19900818
  • Type: Article
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  • p. 1270 –1272 (3)
    A novel approach to grating writing in optical fibres is described. This method involves writing the grating point by point through the side of the fibre using a UV laser source. Efficient mode conversion between forward propagating modes is demonstrated. The wavelength at which conversion occurs is determined by the periodicity of the grating. The grating can be designed to couple light at any wavelength of interest.
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Microstrip balanced diode mixers for X-band frequencies
Optimum optical modulation index of laser transmitters in scm systems
  • Author(s): K. Alameh  and  R.A. Minasian
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1273 –1275
  • DOI:  10.1049/el:19900820
  • Type: Article
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  • p. 1273 –1275 (3)
    An analysis of the optimum optical modulation index of laser transmitters in SCM systems is presented. Nonlinear distortion arising from overmodulation in a laser-limiter combination is studied. A generalised analysis, based on rectangular signal input power spectral density and broadband transmission, is given for the nonlinear noise spectral density. A computer algorithm is developed to generate the optimum modulation index which maximises the received CNR for SCM transmission.
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Non-steady-state photovoltage in crystals with long photoconductivity relaxation times
  • Author(s): I.A. Sokolov  and  S.I. Stepanov
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1275 –1277
  • DOI:  10.1049/el:19900821
  • Type: Article
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  • p. 1275 –1277 (3)
    The effect of non-steady-state photovoltage in photoconductive crystals for high excitation frequencies is discussed. The theoretical analysis based on the widely accepted model of a photoconductor with one partially compensated donor level and a finite photoelectron lifetime is in reasonable agreement with the expirements on cubic BSO crystals. Average lifetimes of photocarners in the samples were estimated to be τ = 10−4 s for λ = 442nm and τ = 3 × 10−6s for λ = 663 nm.
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New GaSb/AlSb/GaSb/AiSb/InAs/AiSb/InAs triple-barrier interband tunnelling diode
  • Author(s): L. Yang ; J.F. Chen ; A.Y. Cho
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1277 –1279
  • DOI:  10.1049/el:19900822
  • Type: Article
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  • p. 1277 –1279 (3)
    A new GaSb/AlSb/GaSb/AlSb/InAs/AlSb/InAs triple-barrier interband tunnelling diode (TBIT) is proposed and demonstrated. A peak-current density as high as 7.2kA/cm2 and a peak-to-valley-current ratio of 10 at room temperature were exhibited. In this device resonant tunnelling effects occur for both the electron in the InAs conduction band and the light hole in the GaSb conduction band through the AlSb/GaSb/AlSb/InAs/AlSb triple-barrier structure. The tunnelling process is greatly diminished, indicating the quantisation effect for both electrons and light holes by narrowing the InAs well and the GaSb well. This triple-barrier structure is the first demonstrated tunnelling structure which utilises the resonant tunnelling effect of both electrons and holes.
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1.7 GHz propagation measurements for highway microcells
Simultaneous transmission and amplification of 622 Mbit/s, 10 FM NTSC video channels and 3 FM HDTV components using a high gain erbium doped fibre amplifier
  • Author(s): H.E. Tohme ; C.N. Lo ; M.A. Saifi
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1280 –1282
  • DOI:  10.1049/el:19900824
  • Type: Article
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  • p. 1280 –1282 (3)
    The simultaneous transmission and amplification of base-band 622 Mbit/s, 10 FM NTSC video channels and three FM HDTV components, subcarrier multiplexed on one wavelength, using a high gain erbium doped fibre amplifier is reported. The full menu was successfully transmitted over 15 km of fibre, and distributed to 8192 terminals. A system power budget of 49.5 dB was measured for an amplifier gain of 31.5dB.
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Modelling of wideband proximity coupled microstrip array elements
Approximate analytical model for the poly-silicon thin film transistor
  • Author(s): M.J. Izzard ; P. Migliorato ; W.I. Milne
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1284 –1286
  • DOI:  10.1049/el:19900826
  • Type: Article
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  • p. 1284 –1286 (3)
    A set of analytical equations that accurately model the large-signal current-voltage and charge-storage characteristics of the poly-silicon thin film transistor (TFT) has been developed. The model is based on theories of conduction in materials with an exponential distribution of states in the gap. The equations are suitable for incorporation into a circuit simulator capable of transient analysis of circuits, such as SPICE.
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Self-routing fast packet switch with in-service modulator growth
High voltage microwave DC block for microstrip ground planes
Error correcting coding of a 220 Mbit/s coherent optical communication channel
  • Author(s): D.M. Castagnozzi ; S.B. Alexander ; E.P. Colagiuri ; E.A. Bucher ; L.L. Jeromin
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1288 –1290
  • DOI:  10.1049/el:19900829
  • Type: Article
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  • p. 1288 –1290 (3)
    Coherent optical communication systems that employ semiconductor lasers have exhibited degraded performance caused by laser phase noise. A rate 1/2, constraint length of seven, convolutional code with hard decision, Viterbi decoding has been applied to an experimental 220 Mbit/s optical FSK channel. Code testing has demonstrated the ability to improve system efficiency and significantly reduce the effect of laser linewidth on bit error rate performance, verifying prior theoretical work.
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FiEnd filters: passive multilayer thin-film optical filters deposited on fibre ends
Reliable 1.3 μm gain guided stripe lasers grown by MOCVD using ethyldimethylindium as the In source
  • Author(s): C. Blaauw ; T.F. Devenyi ; B. Capron ; F.R. Shepherd ; A.J. Springthorpe
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1291 –1293
  • DOI:  10.1049/el:19900831
  • Type: Article
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  • p. 1291 –1293 (3)
    The first semiconductor laser in the GalnAsP materials system grown by MOCVD using ethyldimethylindium as the In source is reported. A 1.3 μm gain guided stripe laser structure with 5 μm wide stripes was fabricated. The devices showed excellent reliability, with negligible degradation measured during life testing at 50°C and 60°C over a period of 16000 h.
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Large bandwidth aperture-coupled microstrip antenna
New radiating edges coupling model for the gap between two rectangular microstrip patch antennas
Analogue computation using VLSI neural network devices
1.54 μm electroluminescence in MeV ion implanted Er-doped GaAs
  • Author(s): P.B. Klein ; F.G. Moore ; H.B. Dietrich
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1299 –1300
  • DOI:  10.1049/el:19900835
  • Type: Article
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  • p. 1299 –1300 (2)
    Er3+ electroluminescence at 1.54 μm has been observed from p-n junction diodes fabricated from ≈ 1 μm Er doped GaAs layers produced by high energy ion implantation. These unique junctions are formed directly by the p-type conversion of the n-type substrate material within the implantation profile. The low efficiencies observed in these devices ( n ≈ 10−6) are believed to be related to the small fraction of the implanted Er in the Er3+ state.
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Fine tuning of wavevector conservation in guided wave devices by photobleaching
Extension of the multiparabolic ionospheric model to the F1-layer L-condition
All-fibre optical hybrid for coherent polarisation diversity receivers
  • Author(s): J.-M.P. Delavaux ; Y.K. Park ; S. Barski ; H. Lefevre ; M. Failes ; C. Warner
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1303 –1305
  • DOI:  10.1049/el:19900838
  • Type: Article
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  • p. 1303 –1305 (3)
    The design, fabrication and characterisation of an all polarisation maintaining fibre coherent hybrid at λ = 1.55μm utilising a polarisation splitter coupler and a 3 dB coupler tree is reported. The compact packaged coupler-based hybrid exhibits low excess insertion loss (less than 0.6 dB), wide operation-bandwidth (greater than 100 nm) and high polarisation crosstalk ratio. Stable operation of the hybrid functions has been demonstrated in a polarisation diversity configuration transmission system experiment at l.7 Gbit/s and 2.5 Gbit/s, with receiver sensitivities of −42 and −38 dBm, respectively.
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Performance of the leaky bucket policing mechanism for small bucket depths
Modelling of materials with electric and magnetic losses with the symmetrical condensed tlm method
High efficiency (1.2 mW/mA) top-surface-emitting GaAs quantum well lasers
  • Author(s): Y.H. Lee ; B. Tell ; K. Brown-Goebeler ; J.L. Jewell ; R.E. Leibenguth ; M.T. Asom ; G. Livescu ; L. Luther ; V.D. Mattera
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1308 –1310
  • DOI:  10.1049/el:19900841
  • Type: Article
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  • p. 1308 –1310 (3)
    Highly efficient (1.2 mW/mA, >70% CW differential quantum efficiency), top-surface-emitting, vertical cavity lasers are achieved at room temperature. Buried damage layers by proton implantation are used for efficient current funnelling. The CW threshold currents are 3.5–8.0 mA, at 3.7–4.2 V bias, for 10.30 μm diameter lasers. The lasing wavelengths are 845–848 nm.
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Distortion minimisation in pulse width modulated systems using a digital sampling process
  • Author(s): S.P. Leigh ; P.H. Mellor ; B.G.M. Cheetham
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1310 –1311
  • DOI:  10.1049/el:19900842
  • Type: Article
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  • p. 1310 –1311 (2)
    The use of digital techniques for pulse width modulation conversion offers greater flexibility than traditional analogue methods. A technique is described that allows the PWM sampling process to be varied over a range of possibilities which offer different compromises between the type of distortion produced by natural and uniform sampling. With optimisation of a parameter, use of this process can lead to an overall reduction in distortion compared with conventional analogue techniques.
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Role of satellite valleys in ionisation rate enhancement in multiple quantum well avalanche photodiodes
  • Author(s): I.K. Czajkowski ; J. Allam ; A.R. Adams
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1311 –1313
  • DOI:  10.1049/el:19900843
  • Type: Article
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  • p. 1311 –1313 (3)
    The enhancement of the electron ionisation rate in multiple quantum well avalanche photodiodes is determined by the band offsets in the satellite valleys rather than the Γ valley as previously assumed for semiconductors where the threshold field for the Gunn effect is less than that for impact ionisation. Monte Carlo calculations in a model GaAs/Al0.45Ga0.55As heterostructure show no enhancement caused by the band offsets.
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Extension of the Smith construction for self orthogonal array codes
Computation of Wigner-Ville distribution for complex data
Low-threshold monomode ion-exchanged waveguide lasers in neodymium-doped BK-7 glass
Determining the number of hidden nodes by progressive training
New zero-voltage-switching constant-frequency PWM DC/DC convertor with low switch stress and wide linearity
  • Author(s): I.D. Kim ; E.C. Nho ; G.H. Cho
  • Source: Electronics Letters, Volume 26, Issue 16, p. 1320 –1321
  • DOI:  10.1049/el:19900848
  • Type: Article
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  • p. 1320 –1321 (2)
    A new zero-voltage-switching (ZVS) DC/DC convertor which operates on constant frequency and has wide linearity is proposed. ZVS operations are achieved not only for the primary switches but also for the secondary rectifier diodes to reduce the switch stresses and losses. The proposed convenor also overcomes the other shortcomings of the conventional resonant DC/DC convertors such as high VA ratings of devices and passive components, load-dependent DC characteristics, etc.
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Fuzzy algorithm for error-correcting estimation of radar signals
Erratum: Improved convergence of iterative scheme for analysing arrays of finite size
Erratum: Measurement and theory of mode hopping in external cavity lasers
Erratum: Monolithic integration of an InGaAs/GaAs/AlGaAs strained layer SQW LED and GaAs MESFET using epitaxial lift-off
Erratum: Analysis of arbitrarily shaped coax-fed microstrip antennas with thick substrates

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