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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 29, Issue 25, 9 December 1993

Volumes & issues:

Volume 29, Issue 25

9 December 1993

Aperture coupled microstrip patch antenna fed by nonradiating dielectric waveguide
Dual reflector antenna with narrow broadside beam for omnidirectional coverage
  • Author(s): M. Orefice  and  P. Pirinoli
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2158 –2159
  • DOI:  10.1049/el:19931448
  • Type: Article
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  • p. 2158 –2159 (2)
    A new type of high gain omnidirectional antenna is presented, particularly suited for higher frequencies (e.g. milllimetre waves): it is obtained with an axially symmetric dual reflector system, fed with an unconventional feed with conical pattern. The feed radiated field, after reflection on the parabolic subreflector and on the conical main reflector, is uniformly scattered in the plane perpendicular to the axis of the system, with vertical polarisation and narrow vertical beamwidth.
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Asymptotic shaping gains from non-Gaussian distributions
Bandwidth expressions of Gaussian weighted chirp
Comparison of two retransmission request mechanisms for trellis coded modulation
Low-delay hybrid vector excitation linear predictive speech coding
Method for efficient location area planning in mobile telecommunications
  • Author(s): J.G. Markoulidakis  and  E.D. Sykas
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2165 –2166
  • DOI:  10.1049/el:19931453
  • Type: Article
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  • p. 2165 –2166 (2)
    Location area dimensioning is based on the tradeoff between the amount of signalling generated due to paging and location updating. The Letter presents a new approach which compares the frequency of location updates per mobile terminal with the frequency of mobile terminating calls. This leads to the concept of useless location updating, when location updating occurs but this information is not subsequently used.
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Multiple-symbols differential detection of GMSK
  • Author(s): A. Abrardo ; G. Benelli ; G. Cau
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2167 –2168
  • DOI:  10.1049/el:19931454
  • Type: Article
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  • p. 2167 –2168 (2)
    A new differential detection algorithm using multiple-symbol observation interval for the demodulation of a GMSK signal is described. This technique is based on a maximum-likelihood sequence estimation of the transmitted phases rather than symbol-by-symbol detection. Upper and lower bounds on the bit error probability of the described detector in the case of an AWGN channel are derived. Comparisons with the classical coherent detection algorithm of a CPM signal show that the proposed detection algorithm is quite attractive.
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New diversity receiver for mobile communications
  • Author(s): A. Abrardo ; G. Benelli ; A. Bini ; A. Garzelli
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2168 –2169
  • DOI:  10.1049/el:19931455
  • Type: Article
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  • p. 2168 –2169 (2)
    The performance of a new diversity receiver in a mobile radio communication system is analysed. The proposed scheme, based on the classical MLSE Viterbi algorithm, uses a new distance combination technique for GMSK signal demodulation. Comparisons with the classical Viterbi algorithm show that the bit error rate can be significantly decreased, with a slight increase in the receiver complexity.
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New simple encoder and trellis decoder for Golay codes
Noise performance of the pulse slope modulation system
Relationship between performance and timing recovery mechanisms for a DECT link in dispersive channels
  • Author(s): L.B. Lopes  and  S. Safavi
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2173 –2174
  • DOI:  10.1049/el:19931458
  • Type: Article
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  • p. 2173 –2174 (2)
    The performance of DECT (digital European cordless telecommunications) radio links under dispersive channel conditions is studied as a function of clock recovery strategies. It is shown that due to the non-optimal sampling, analytical and practical results based on fixed timing will not be acceptable above delay spreads of ∼40ns. On the other hand, a burst-adaptive clock recovery scheme can more than double this range.
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Scheduling cells in an input-queued switch
Statistical modelling of spectrum occupancy
Time-domain design of low delay wavelet transforms
  • Author(s): A. Al-Adnani ; R. Chapman ; T.S. Durrani
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2177 –2178
  • DOI:  10.1049/el:19931461
  • Type: Article
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  • p. 2177 –2178 (2)
    The Letter uses a time-domain design methodology previously used for perfect reconstruction filter banks to design wavelet prototypes which may be used to generate the discrete wavelet transform (DWT). An advantage of this method is the significant reduction in the inherent delay, and consequent reduction in the number of multiplications required to implement the DWT. It is proposed that these low delay wavelets will find applications in time critical systems.
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High performance scaled flash-type EEPROMs fabricated by in situ multiple rapid thermal processing
  • Author(s): T. Hayashi ; Y. Kawazu ; H. Fukuda ; T. Iwabuchi
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2178 –2179
  • DOI:  10.1049/el:19931462
  • Type: Article
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  • p. 2178 –2179 (2)
    Flash-type EEPROMs were fabricated for the first time by in situ multiple rapid thermal processing (RTP) modules. In the Letter, rapid thermal oxynitridation tunnel oxide (RTONO) formation followed by in situ arsenic (As)-doped floating gate polysilicon growth by rapid thermal chemical vapour deposition (RTCVD) were introduced. The flash cell indicates only 20% narrowing of the Vt window after 5 × 104 program/erase cycle stress. Moreover, there is a higher breakdown field of the ONO film on the floating-gate polysilicon film owing to extremely flat poly-Si surface. Thus, the in situ multiple RTP technology is the key for future flash memory fabrication processes.
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Stepped model of smooth irregularities corrected for location of equivalent reflection surface
54MHz switched-capacitor video channel equaliser
Gabor-QR decomposition for image encoding
  • Author(s): P. Lau ; N.P. Papanikolopoulos ; D.L. Boley
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2182 –2183
  • DOI:  10.1049/el:19931465
  • Type: Article
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  • p. 2182 –2183 (2)
    A new approach to Gabor transformation based on the QR decomposition, with potential applications to image sequence encoding, is proposed. This Gabor-QR scheme computes the exact Gabor coefficients by solving a system of linear equations Ax = b, which is more efficient than iterative schemes, and less complicated than other matrix-based methods. Experimental results from image encoding are presented.
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Bulk encryption algorithm for use with RSA
New signature scheme with message recovery
16Gbit/s multiplexer IC using double mesa Si/SiGe heterojunction bipolar transistors
  • Author(s): H.-U. Schreiber ; J.N. Albers ; B.G. Bosch
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2185 –2187
  • DOI:  10.1049/el:19931468
  • Type: Article
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  • p. 2185 –2187 (3)
    A double mesa Si/SiGe heterojunction bipolar transistor (HBT) was developed for application in integrated circuits. The HBT is characterised by an emitter base heterojunction and consequently by a high base doping concentration. By using these transistors an integrated digital circuit, a multiplexer, was implemented. The measured bit rate of this first Si/SiGe HBT circuit was 16Gbit/s.
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Application of a multivariable optimiser to the design of CMOS buffers
New domino logic precharged by clock and data
  • Author(s): J.-R. Yuan ; C. Svensson ; P. Larsson
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2188 –2189
  • DOI:  10.1049/el:19931470
  • Type: Article
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  • p. 2188 –2189 (2)
    A clock-and-data precharged dynamic (CDPD) circuit technique in CMOS is presented. It gives a fast one-clock-cycle decision to multilevel logic and has small clock loads, low peak current, small area and low power-delay product. The technique is highly flexible in logic design. For the given example, a 324bit binary-lookahead-carry chain, the speed improvement can be as high as 40–50% compared to the static circuit and 30% to the normal domino circuit arrangements while the area is reduced by 15–30%.
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Nonlinear switched-current CMOS IC for random signal generation
  • Author(s): M. Degaldo-Restituto ; F. Medeiro ; A. Rodríguez-Vázquez
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2190 –2191
  • DOI:  10.1049/el:19931471
  • Type: Article
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  • p. 2190 –2191 (2)
    A nonlinear switched-current circuit is presented that implements a chaotic algorithm for the generation of broadband, white analogue noise. The circuit has been fabricated in a double-metal, single-poly 1.6μm CMOS technology and uses a novel, highly accurate CMOS circuit strategy to realise piecewise-linear characteristics in the current-mode domain. Measurements from the silicon prototype show a flat spectrum from DC to ∼30% of the clock frequency, for a clock frequency of 500kHz.
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Settling time reduction technique for high speed DACs
Continuous-wave, room temperature, ridge waveguide green-blue diode laser
Continuous-wave operation of 489.9 nm blue laser diode at room temperature
  • Author(s): N. Nakayama ; S. Itoh ; H. Okuyama ; M. Ozawa ; T. Ohata ; K. Nakano ; M. Ikeda ; A. Ishibashi ; Y. Mori
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2194 –2195
  • DOI:  10.1049/el:19931474
  • Type: Article
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  • p. 2194 –2195 (2)
    At room temperature (296 K), continuous-wave (CW) operation of a blue laser diode has been achieved. The emission wavelength is 489.9 nm, and the threshold current and voltage is 93 mA (1.5 kA/cm2) and 6.3 V, respectively. The laser consists of a ZnCdSe/ZnSSe/ZnMgSSe single-quantum-well (SQW) separate-confinement heterostructure (SCH).
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DBR laser array for WDM system
Integrable InGaAs/GaAs vertical-cavity surface-emitting lasers
  • Author(s): B.J. Thibeault ; J.W. Scott ; M.G. Peters ; F.H. Peters ; D.B. Young ; L.A. Coldren
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2197 –2199
  • DOI:  10.1049/el:19931476
  • Type: Article
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  • p. 2197 –2199 (3)
    A new electrically isolated bottom-emission vertical-cavity surface-emitting laser structure with a novel contacting method is demonstrated. The structure is grown on semi-insulating material and contacts are made to an n-type intracavity contact layer and the top of a low-resistance Al0.67Ga0.33As/ GaAs p-type distributed Bragg reflector. This structure offers the advantages of device isolation and low parasitic capacitance without sacrificing performance. Small devices (10μm or less in diameter) perform as well as the best lasers reported in the literature.
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SiNx/sulphide passivated GaAs/AlGaAs microdisk lasers
Spectral and temporal stabilisation of a diode-pumped ytterbium-erbium fibre soliton laser
Anisotropic etching of deep trench for silicon monolithic microwave integrated circuit
  • Author(s): T.C. Lo  and  H.C. Huang
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2202 –2203
  • DOI:  10.1049/el:19931479
  • Type: Article
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  • p. 2202 –2203 (2)
    The anisotropic etching of deep trenches in bulk Si for isolating global buried collectors in Si monolithic microwave integrated circuits has been successfully developed with SF6/C2CIF5 gas mixtures. Using photoresist as the etching mask, deposition of polymer thin film on the sidewalls of the trench occurred, hence inhibiting lateral etching and made the process anisotropic. Under optimal processing conditions, an etching anisotropy of 0.98 and an etching selectivity of silicon to photoresist higher than 28 were observed.
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Effect of mode launcher geometry on the performance of a mode-selective input coupler for a gyrotron amplifier
  • Author(s): J.P. Tate ; H. Guo ; M. Naiman ; L. Chen ; V.L. Granatstein
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2203 –2205
  • DOI:  10.1049/el:19931480
  • Type: Article
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  • p. 2203 –2205 (3)
    In the process of developing a wideband input coupler for a gyrotron amplifier, the authors have measured the scalar reflection coefficient for three mode launching geometries, each mounted coa.xially in an overmoded circular waveguide. A helical structure is fed directly from a 50Ω TEM coaxial line. The impedance match is significantly affected by changes in the helix and helix support structure. A bandwidth from 16.5 to 18GHz is demonstrated from a TE02 mode input coupler for one of the geometries under study.
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Substrate integrated transition between a planar millimetre wave antenna and hermetically sealed integrated circuits
Functional testing for cellular neural networks
Relation between template spectrum and convergence of discrete-time cellular neural networks
  • Author(s): R. Perfetti
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2208 –2209
  • DOI:  10.1049/el:19931483
  • Type: Article
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  • p. 2208 –2209 (2)
    A convergence criterion is proposed for reciprocal, discrete-time cellular neural networks, that exploits the peculiar interconnection structure of such networks. It is based on the Fourier spectrum of the discrete sequence representing the cloning template, and can be applied in the usual case where the neighbourhood is much smaller than the network. The corresponding design constraint, involving the template values, results in being less restrictive than those existing in the literature.
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10 Gbit/s unrepeatered three-level optical transmission over 100 km of standard fibre
Fully time-division-multiplexed 100 Gbit/s optical transmission experiment
Measurement of dispersion and nonlinearity in murtiamplifier systems
  • Author(s): S. Pycock ; M. Mulvey ; D. Butler
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2212 –2214
  • DOI:  10.1049/el:19931486
  • Type: Article
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  • p. 2212 –2214 (3)
    A lightwave component analyser is used to measure the frequency response of a 6300km optically amplified testbed. The position of the nulls is shown to be very sensitive to the fibre parameters and the optical power level and agrees well with numerical predictions. Such measurements could be used to detect any changes occurring between factory tests and the installation of a long-haul optically amplified system.
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Modification of optical coherence using spectral phase coding for use in photonic code-division multiple access systems
Polarisation-independent phase conjugation of lightwave signals
Optically-biased, edge-coupled InP/InGaAs heterojunction phototransistors
  • Author(s): D. Wake ; D.J. Newson ; M.J. Harlow ; I.D. Henning
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2217 –2219
  • DOI:  10.1049/el:19931489
  • Type: Article
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  • p. 2217 –2219 (3)
    InP/GaAs heterojunction phototransistors are reported with high DC gain (greater than 270) and high unity-gain frequency (greater than 30GHz). To the authors' knowledge, these are the highest performance heterojunction phototransistors reported to date. This performance is achieved by a combination of edge-coupled optical access and a two-terminal, optically-biased design. This design allows efficient, small area devices with low parasitics to be produced with a simple fabrication scheme.
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Frequency dependence of slant-path amplitude scintillations
  • Author(s): G. Ortgies
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2219 –2220
  • DOI:  10.1049/el:19931490
  • Type: Article
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  • p. 2219 –2220 (2)
    The Letter reports scintillation measurements using the beacons of the Olympus satellite at 12.5, 20 and 30GHz. Based on a period of 30 months, the frequency dependence of amplitude scintillations has been investigated. In the Letter, complete monthly distributions of short-term signal variances, which could be characterised by a single parameter, were taken into account. Results have been compared with those of an earlier investigation based on a one-year subset of the data base. The latter considered only variances which were exceeded for low time percentages. Furthermore, results have been compared with the existing ITU-R scheme and with experimental results found in the literature.
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Enhancement and depletion-mode AlGaAs/In0.15Ga0.85As HEMTs fabricated by selective ion implantation
  • Author(s): Y.-J. Chan  and  M.-T. Yang
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2220 –2222
  • DOI:  10.1049/el:19931491
  • Type: Article
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  • p. 2220 –2222 (3)
    Enhancement- and depletion-mode AlGaAs/In0.15Ga0.85As HEMTs were fabricated on the same wafer by the selective ion implantation technique. This implantation results in extra carriers in the area of D-HEMTs, and therefore E- and D-HEMTs can be realised simultaneously after a single gate lithography step. As compared with the conventional approach, this selective ion implantation provides a convenient method for implementing the E/D-mode logic circuits for high-speed and low-power applications.
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High current density double modulationdoped Al0.48In0.52As-Ga0.65As millimetre-wave HEMT
  • Author(s): F. Gueissaz ; T. Enoki ; Y. Ishii
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2222 –2223
  • DOI:  10.1049/el:19931492
  • Type: Article
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  • p. 2222 –2223 (2)
    0.2μm gate length InP-based HEMTs fabricated on double modulation- doped Al0.48In0.52As - Ga0.35In0.65As heterostructures are shown to yield unprecedented modulation characteristics in terms of high drain current density and high cutoff frequencies. At a record drain current density of 1350mA/mm, the specific transconductance and maximum current gain and unilateral power gain cutoff frequencies (fT and fmaxare as high as ll00 mS/mm, 80GHz and 160GHz, respectively.
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High frequency GaAs/Al0.25Ga0.75As heterojunction bipolar transistors with transparent indium-tin-oxide emitter contacts
  • Author(s): W.Q. Li ; M. Karakucuk ; J. Kulman ; J.R. East ; G.I. Haddad ; P.K. Bhattacharya
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2223 –2225
  • DOI:  10.1049/el:19931493
  • Type: Article
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  • p. 2223 –2225 (3)
    The authors have characterised a GaAs/Al0.25Ga0.75As heterojunction bipolar transistor (HBT) with transparent indium tin oxide (ITO) emitter contacts. An ITO to n-GaAs contact resistance of 2 × 10−7 Ω/ cm2 was measured with 50Å of indium as a prelayer. HBT devices with fT = 18GHz, fmax = 20GHz, and optical pulse response of 80ps FWHM have been measured. The results indicate that this device technology is a good candidate for application in optically controlled microwave circuits.
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Molecular-beam epitaxial growth of pyramidal structures on patterned GaAs(100) substrates for threedimensionally confined structures
Multi-terahertz sidewall-etched varactor diodes and their application in submillimetre-wave sampling circuits
Proposal for the concept of ultradense integrated memories based on Coulomb blockade at room temperature.
  • Author(s): K. Bock  and  H.L. Hartnagel
  • Source: Electronics Letters, Volume 29, Issue 25, p. 2228 –2230
  • DOI:  10.1049/el:19931496
  • Type: Article
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  • p. 2228 –2230 (3)
    Coulomb-blockade results are recorded at room temperature and normal pressure in monolithically integrated structures using GaAs wedges with a radius of ∼25nm and a minimal gap to the anode when a quasi-vacuum can be assumed. These devices have very low capacitances being of order 10−18F. A concept presented where this Coulomb blockade is used for signal production and storage in an ultra-dense memory-matrix application. A one-dimensional high-electron mobility heterostructurc together with local resonant intcrband tunnelling, isolated by deep ion implantation are proposed for the buried layer access electronics.
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Quantum-well intersub-band electroluminescent diode at λ = 5μm
Erratum: High power neodymium-doped single transverse mode fibre laser
Erratum: Impact ionisation in high-output-conductance region of 0.5 μm AlSb/InAs HEMTs

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