Your browser does not support JavaScript!
http://iet.metastore.ingenta.com
1887
banner image
image of Volume 26, Issue 15
Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 26, Issue 15, 19 July 1990

Volumes & issues:

Volume 26, Issue 15

19 July 1990

Improving the characteristics of InAlAs/InGaAs heterojunction bipolar transistors by employing thin base and collector layers
Feasibility demonstration of low pump power operation for 1.48 μm diode-pumped erbium-doped fibre amplifier module
In-situ investigation of coupling between a fibre and a slab waveguide
  • Author(s): M. Iztkovich ; M. Tur ; A. Hardy ; N. Croituro
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1104 –1105
  • DOI:  10.1049/el:19900714
  • Type: Article
  • + Show details - Hide details
  • p. 1104 –1105 (2)
    The mode coupling between a fibre and a slab waveguide was experimentally investigated during the formation of the slab. A thin film has been deposited on a polished fibre close to the core-clad interface. By monitoring the optical transmittance of the fibre during the film deposition the coupling efficiency between the formed slab and the fibre has been studied as a function of the film thickness. Strong attenuation in the fibre output has been observed for thickness values at which the propagation constants of the optical mode in the fibre match those of the slab waveguide.
    Add to favourites
    Export citations
Fault modelling of ECL devices
Soft-decision syndrome based node synchronisation
  • Author(s): J. Sodha  and  D.J. Tait
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1108 –1109
  • DOI:  10.1049/el:19900716
  • Type: Article
  • + Show details - Hide details
  • p. 1108 –1109 (2)
    A node synchronisation technique based on extracting the syndrome sequence, associated with convolutionally encoded received channel symbols, is extended to incorporate soft-decision information. The extension involves defining a measure of confidence per syndrome bit producing a ‘soft’ syndrome. The potential benefits of the new algorithm are investigated. It is shown that improvements are possible but only at the expense of storage requirements.
    Add to favourites
    Export citations
High-performance, two-channel optical FSK heterodyne system with polarisation diversity receiver
High speed opto-electronic neural network
Damaged depth in GaAs processed by Ar plasma etching
  • Author(s): H. Hidaka ; K. Akita ; M. Taneya ; Y. Sugimoto
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1112 –1113
  • DOI:  10.1049/el:19900719
  • Type: Article
  • + Show details - Hide details
  • p. 1112 –1113 (2)
    The damaged depths in GaAs processed by Ar plasma etching under various applied radio-frequency (RF) voltages and Ar pressures in a parallel-plate type apparatus were studied. The damaged depth was evaluated in terms of the chemically etched thickness at which the photoluminescence intensity recovers. The damaged depth decreased as the applied radio frequency peak voltage was decreased. The depth was extraordinarily deep in the lower radio frequency voltage region. The effect of Ar pressure on damaged depth was small in the range from 1 to 10 Pa.
    Add to favourites
    Export citations
High performance metal-clad fibre-optic polarisers
  • Author(s): R. Willsch
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1113 –1115
  • DOI:  10.1049/el:19900720
  • Type: Article
  • + Show details - Hide details
  • p. 1113 –1115 (3)
    The principle of polarisation-selective resonant coupling between a guided optical mode and a metal surface plasmon wave through the evanescent field of the fibre was used to develop fibre-optic polarisers with extinction ratios in excess of 70 dB and losses less than 0.5 dB at 850 nm wavelength. The influence of fibre and thin-film parameters on the polariser performance was investigated both theoretically and experimentally. An improved measurement method for the polariser extinction ratio is demonstrated.
    Add to favourites
    Export citations
Maximum SQNR formula for delta-sigma modulation
Use of co-occurrence matrices in the temporal domain
Switched-capacitor neural networks using pulse based arithmetic
  • Author(s): B. Maundy  and  E. El-Masry
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1118 –1119
  • DOI:  10.1049/el:19900723
  • Type: Article
  • + Show details - Hide details
  • p. 1118 –1119 (2)
    A possible VLSI implementation of a neural network using SC networks is presented. The frequency of a presynaptic pulse is used as a measure of its state, Vj(f). Synaptic multiplication is made possible by controlling input voltages to the SC multiplier and clock frequencies, Vj(f). Programmable positive and negative weights are allowed. The design is asynchronous and does not require any master clocks.
    Add to favourites
    Export citations
Angle resolved X-ray photoemission study of rapid thermal annealing applied to different GaAs and InP samples
  • Author(s): A. Quemerais ; G. Jezequel ; H. L'haridon ; P.N. Favennec ; M. Salvi
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1119 –1122
  • DOI:  10.1049/el:19900724
  • Type: Article
  • + Show details - Hide details
  • p. 1119 –1122 (4)
    The crystalline order and itoechiomctry of the near surface of GaAs and InP substrates after rapid thermal annealing using a silicon wafer as a protecting cap have been deduced from angle resolved X-ray photo-emission measurements. A monolayer of As or P appears to be enough to prevent further material decomposition. For implanted samples (up to 1014/cm2 Si), the crystalline order is restored after the rapid anneal (without any important stoechiometry modification).
    Add to favourites
    Export citations
Water and hydrogen equilibrium for different cable constructions
Accurate modelling of unilateral finline-coplanar waveguide transition
  • Author(s): A. Rong
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1123 –1124
  • DOI:  10.1049/el:19900726
  • Type: Article
  • + Show details - Hide details
  • p. 1123 –1124 (2)
    Using the spectral domain technique in conjunction with finite element slot field expansions, the scattering characteristics of the unilateral finline-coplanar waveguide transition are analysed. Flexible rooftop functions varying in both the transverse and longitudinal directions are used instead of a uniform rooftop function as expansion functions to handle arbitrary slot width structures. A typical example is computed. The numerical results for the special case agree well with those available in the literature.
    Add to favourites
    Export citations
Gate oxide thickness dependence of high-field-induced interface state generation in thin thermal oxides
  • Author(s): G.Q. Lo  and  D.L. Kwong
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1124 –1125
  • DOI:  10.1049/el:19900727
  • Type: Article
  • + Show details - Hide details
  • p. 1124 –1125 (2)
    The oxide thickness dependence of the high-field-induced interface state generation ΔDu in the nanometre-range thin (6–10 nm) gate oxides prepared by rapid thermal oxidation have been studied. It is shown that ΔDu is a strong function of the oxide thickness. The thickness dependence of ΔDu is found to be a function of stress time. Physical mechanisms are discussed to account for the experimental results.
    Add to favourites
    Export citations
16-channel parallel optical interconnect demonstration with an InGaAs/InP MQW modulator array
Evaluation of single ohmic metallisations for contacting both p- and n-type GaInAs
  • Author(s): L.G. Shantharama ; H. Schumacher ; H.P. Leblanc ; R. Esagui ; R. Bhat ; M. Koza
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1127 –1129
  • DOI:  10.1049/el:19900729
  • Type: Article
  • + Show details - Hide details
  • p. 1127 –1129 (3)
    The contact resistivity of various non-alloyed ohmic contact metallisations on both n- and p+-type Ga0.47In0.53As has been investigated. Pd/AuGe metallisation was found to be most suitable when layers of both doping types were to be contacted in a single step, having lower contact resistivities on p+-GaInAs than Ti/Pt/Au and AuBe/Pt/Au, On n+-GaInAs, the contact resistivity was found to be almost independent of the metallisation used.
    Add to favourites
    Export citations
Demodulation of multi-gigahertz frequency-modulated optical signals in an injection-locked distributed feedback laser oscillator
  • Author(s): H. Nakajima
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1129 –1131
  • DOI:  10.1049/el:19900730
  • Type: Article
  • + Show details - Hide details
  • p. 1129 –1131 (3)
    A new type of wavelength selective optical receiver that allows the demodulation of multi-gigaHertz frequency modulated (FM) optical signals is demonstrated by detecting FM light-induced changes in the forward voltage of an optically injection-locked distributed feedback semiconductor laser operating at far above the losing threshold. A bandwidth as wide as 2 GHz is reported together with an FM demodulation efficiency of 52 μV/GHz.
    Add to favourites
    Export citations
Variational approach to nonlinear waveguides—Gaussian approximations
Preliminary reliability studies of 1.55 μm graded index separate confinement buried heterostructure (GRINSCH) multiple quantum well (MQW) lasers grown by metalorganic vapour phase epitaxy (MOVPE)
  • Author(s): R.M. Redstall ; A.P. Skeats ; D.M. Cooper ; A.L. Burness
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1132 –1133
  • DOI:  10.1049/el:19900732
  • Type: Article
  • + Show details - Hide details
  • p. 1132 –1133 (2)
    1.55 μm graded index separate confinement heterostructure (GRINSCH) multi-quantum-well (MQW) lasers, grown entirely by metalorganic vapour phase epitaxy (MOVPE), have demonstrated low degradation rates in lifetests at 50°C, 4 mW per facet. These lasers are complex structures, containing many interfaces, and the encouraging early lifetest results demonstrate the ability of MOVPE to grow these structures.
    Add to favourites
    Export citations
Statistical AR models for the frequency selective indoor radio channel
  • Author(s): K. Pahlavan  and  S.J. Howard
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1133 –1135
  • DOI:  10.1049/el:19900733
  • Type: Article
  • + Show details - Hide details
  • p. 1133 –1135 (3)
    A statistical model of the indoor radio channel is proposed that is derived from a second order autoregressive process representation of the channel frequency response. The accuracy of the statistical model is examined by comparing the cumulative distribution functions of the RMS delay spread and the 3dB width of the frequency correlation function computed from the regenerated data with that of the measurements performed in two indoor radio propagation studies in the 0.9–1.1 GHz band.
    Add to favourites
    Export citations
Analysis of edge slots in rectangular waveguide using finite-difference time-domain method
Novel learning method for analogue neural networks
Slant path 30 to 12.5 GHz copolar phase difference, first results from measurements using the Olympus satellite
Method for computing the stability margin of 2-D discrete systems
Rate 1/2 180° phase-invariant convolutional coding with differentially-encoded coherent QPSK for band-limited AWGN channels
  • Author(s): L.H.C. Lee
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1141 –1142
  • DOI:  10.1049/el:19900738
  • Type: Article
  • + Show details - Hide details
  • p. 1141 –1142 (2)
    Rate-1/2 180° phase-invariant convolutional coding and unquantised maximum-likelihood Viterbi decoding with differentially-encoded coherent QPSK (DE-QPSK) for bandlimited additive white Gaussian noise (AWGN) channels are considered. The simulated bit error probability performance of the trellis-coded modulation is presented for four- and eight-state convolutional codes of constraint lengths three and four, respectively.
    Add to favourites
    Export citations
High speed low power GaAs crosspoint switch design
Integrated-optic interferometric microdisplacement sensor in glass with thermo-optic phase modulation
Novel ternary JKL flip-flop
1.5 Gbit/s FSK transmission system using two electrode DFB laser as a tunable FSK discriminator/photodetector
Lossless transmission over 10 km of low-dispersion erbium doped fibre using only 15 mW pump power
Erbium fibre soliton laser
Dimensional correction of high dielectric and magnetic constants determined by S parameters measurements
Parabolic equation modelling of propagation over irregular terrain
Pulsed operation of an optical feedback frequency synthetiser
High speed linear array circuit with AlAaAs/GaAs heterojunction bipolar transistors (HBTs)
  • Author(s): L.M. Lunardi ; V.D. Archer ; R.G. Swartz ; J.M. Kuo ; R.F. Kopf ; R.J Malik ; P.R. Smith
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1157 –1159
  • DOI:  10.1049/el:19900748
  • Type: Article
  • + Show details - Hide details
  • p. 1157 –1159 (3)
    Direct comparison of the performance of a digital divide-by-two implemented in a linear array configuration with an optimised layout version has been made, using AlGaAs/GaAs HBTs in 3.5 μm emitter width technology with a cutoff frequency of 40 GHz. The customised version operated up to 7.5 GHz input frequency. The linear array circuit operated up to 7.05 GHz.
    Add to favourites
    Export citations
Temperature and mechanical vibration characteristics of a miniature long external cavity semiconductor laser
  • Author(s): S.A. Al-Chalabi ; J. Mellis ; M. Hollier ; K.H. Cameron ; R. Wyatt ; J.E. Regnault ; W.J. Devlin ; M.C. Brain
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1159 –1160
  • DOI:  10.1049/el:19900749
  • Type: Article
  • + Show details - Hide details
  • p. 1159 –1160 (2)
    The operation of a miniature LEC laser was maintained in the same longitudinal mode while the ambient temperature was cycled between 5 and 40°C. The optical frequency deviation was reduced to less than 120 MHz for a 2 m/s2 mechanical vibration level in the frequency range 40 Hz–20 kHz. The LEC operated continuously in the same mode for an observation period >1680h (70 days).
    Add to favourites
    Export citations
Analysis of stripline/slot transition
Novel method of dro frequency tuning with varactor diode
Room temperature negative differential resistance in a triple well rectifying resonant tunnelling diode
Nonlinear triple core couplers
Monolithic integration of 1.5 μm optical preamplifier and PIN photodetector with a gain of 20 dB and a bandwidth of 35 GHz
Fast timing extraction method for an optical passive bus
  • Author(s): Y. Nagasako  and  T. Nakashima
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1168 –1169
  • DOI:  10.1049/el:19900755
  • Type: Article
  • + Show details - Hide details
  • p. 1168 –1169 (2)
    A new timing extraction method that uses a tank circuit for bursty transmissions on an optical passive bus is proposed. The tank circuit has two quality factor values. In the preamble field the value of Q is low so as to extract the timing clock from short preambles. In the transferring field the value of Q is high to retain the extracted timing clock even if a less redundant code is used. It is confirmed by an optical transmission experiment that the proposed method can achieve fast bit timing extraction from a four bit preamble at 600 Mbit/s.
    Add to favourites
    Export citations
ID-based authentication system for computer virus detection
  • Author(s): E. Okamoto  and  H. Masumoto
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1169 –1170
  • DOI:  10.1049/el:19900756
  • Type: Article
  • + Show details - Hide details
  • p. 1169 –1170 (2)
    Authentication systems for computer virus detection are presented. The systems are based on identity-based signature schemes which can simplify the system management. In the systems a software maker signs software with his own secret key and users verify whether the software is infected with computer virus or not using one public key. Users have only to keep the public key, instead of keys corresponding to each software maker. The key management can therefore be simplified by the use of ID-based authentication systems.
    Add to favourites
    Export citations
Interpolation using type i discrete cosine transform
InAIAs/InGaAs/InP junction HEMTs
Passive electrical vernier for measuring mask misalignment
Simple method for calculating optimum cut of piezoelectric material with small baw generation by IDTS
  • Author(s): J.H. Yin ; Y. Shui ; D. Zhang ; J. Yu ; P. Wu
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1175 –1176
  • DOI:  10.1049/el:19900760
  • Type: Article
  • + Show details - Hide details
  • p. 1175 –1176 (2)
    A method is presented for calculating the optimum cut of piezoelectric material with small bulk acoustic wave (BAW) generation by interdigital transducers (IDTs). The theoretical results for Y-rotated cut X-propagation and Y-rotated cut X-90° propagation LiNbO3 are given. A new cut of LiNbO3 has been found which has smaller BAW generation than Y-128°X LiNbO3. The experimental results agree with the theoretical prediction.
    Add to favourites
    Export citations
Modified Lin formula for calculating fadings caused by hydrometeors on terrestrial paths in Czechoslovakia
Some comments on damgard's hashing principle
Integration of GaAs MESFETs and lithium niobate optical switches using epitaxial lift-off
  • Author(s): A.C. O'Donnell ; I. Pollentier ; P. Demeester ; P. Van Daele ; A.D Carr
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1179 –1181
  • DOI:  10.1049/el:19900763
  • Type: Article
  • + Show details - Hide details
  • p. 1179 –1181 (3)
    The first successful integration of GaAs MESFETs and lithium niobate optical switches using the epitaxial lift-off technique is reported. The interferometric switch produced an extinction ratio >30 dB at 1300 nm for an input voltage swing to the MESFET of only 240 mV. This realisation holds out interesting prospects for the development of novel, efficient and cost-effective quasi-monolithic integrated optoelectronic circuits.
    Add to favourites
    Export citations
Crosstalk injection when testing transmission systems
  • Author(s): J.W. Cook  and  K.T. Foster
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1181 –1183
  • DOI:  10.1049/el:19900764
  • Type: Article
  • + Show details - Hide details
  • p. 1181 –1183 (3)
    One of the key performance requirements specified for local loop transmission systems is that of performance in the presence of crosstalk. Objective testing requires the injection of known levels of synthetic crosstalk into test copper pair loops with variable and frequency dependent impedances. It has been shown that a transformer with multiple secondaries in combination with a high performance buffer amplifier can be used to inject controlled levels of synthetic crosstalk without the use of complicated calibration procedures.
    Add to favourites
    Export citations
Minimum entropy deconvolution for restoration of blurred two-tone images
VLSI architecture for the discrete wavelet transform
New design technique for two-step flash A/D convertors
Monolayer Be δ-doped heterostructure bipolar transistor fabricated using doping selective base contact
  • Author(s): T.Y. Kuo ; J.E. Cunningham ; K.W. Goossen ; W.Y. Jan ; C.G. Fonstad ; F. Ren
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1187 –1188
  • DOI:  10.1049/el:19900768
  • Type: Article
  • + Show details - Hide details
  • p. 1187 –1188 (2)
    A heterostructure bipolar transistor (HBT) with a base δ-doping of 6×1014cm−2, near the physical limit of one monolayer (ML) is reported. The devices exhibits a current gain of 15. The doping confinement of the δ layer is 15 Å. To fabricate the HBT without inducing dopant diffusion or using sensitive etching, a new low-temperature basecontacting procedure (Tmax = 420°C) which requires no base-emitter etching has been development. This has the additional benefits of greatly reducing surface recombination and yielding a planar structure.
    Add to favourites
    Export citations
Simple expression of rectangular patch's resistance at resonance
Analysis of a pre-emptive priority M/M/c model with two types of customers and restriction
Analysis of ATM switch model (GEO/ATD/1) with time priorities
Chemically stabilised ion implanted waveguides in sapphire
  • Author(s): P.D. Townsend ; P.J. Chandler ; R.A. Wood ; L. Zhang ; J. McCallum ; C.W. McHargue
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1193 –1195
  • DOI:  10.1049/el:19900772
  • Type: Article
  • + Show details - Hide details
  • p. 1193 –1195 (3)
    Formation of optical waveguides in crystals is extremely attractive for low threshold single mode lasers in materials such as ruby and titanium sapphire. Previous attempts to achieve this using helium ion implantation required unacceptable high ion doses, leading to failure of the surface. The first demonstration of waveguide formation by ion implantation to chemically stabilise defects is reported. Stable waveguides have been prepared using doses as small as 1016 ions/cm2 under optimum implant conditions.
    Add to favourites
    Export citations
Experimental observation of forward stimulated Brillouin scattering in dual-mode single-core fibre
Optimised design for a 0.5 μm gate length n-channel SOI MOSFET
  • Author(s): G.A. Armstrong  and  W.D. French
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1196 –1198
  • DOI:  10.1049/el:19900774
  • Type: Article
  • + Show details - Hide details
  • p. 1196 –1198 (3)
    Two dimensional device simulation has been used to optimise the design of an n-channel silicon-on-insulator MOSFET with an ultra thin film. The trade-off between SOI film thickness and film doping on the threshold voltage, inverse subthreshold slope and breakdown voltage is considered. The effect of carrier lifetime on the breakdown voltage is described. Use of a lightly doped drain gives a simulated breakdown voltage greater than 3.5 V for a transistor with a film thickness of 1000 Å and a gate length of 0.5 μm.
    Add to favourites
    Export citations
Monolithically integrated In0.53Ga0.47As/In0.52Al0.48As (on InP) MSM/HFET photoreceiver grown by MBE
  • Author(s): H.T. Griem ; H.S. Fuji ; T.J. Williams ; J.P. Harrang ; R.R. Daniels ; S. Ray ; M.J. Lagasse ; D.L. West
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1198 –1200
  • DOI:  10.1049/el:19900775
  • Type: Article
  • + Show details - Hide details
  • p. 1198 –1200 (3)
    High speed results on In0.53, Ga0.47As/ln0.52Al0.aAs (on InP) planar doped heterojunction-FETs and 1.3–1.6μ wavelength-compatible metal-semiconductor-metal photodetector devices fabricated from a vertically stacked device design with the FET overlaying the detector structure are reported. A cut-off frequency for unity current gain of 30GHz was achieved with a 1μ gatelength. The photodetector at 7 V bias had a photoresponse and dark current of 0.48 A/W and 24 nA, respectively. At 10 V bias the FWHM of the impulse response was 65 ps. A simple near-planar monolithically integrated photoreceiver was successfully fabricated requiring no special processing or regrowth steps.
    Add to favourites
    Export citations
Performance trade-offs in SAW group-type SPUDTs
Directivity of group-type single phase unidirectional SAW transducers
Structures and microwave losses in Ni/Cu/Ni/Au coatings on alumina
Quiescent current sensor circuits in digital VLSI CMOS testing
  • Author(s): A. Rubio ; J. Figueras ; J. Segura
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1204 –1206
  • DOI:  10.1049/el:19900779
  • Type: Article
  • + Show details - Hide details
  • p. 1204 –1206 (3)
    Many integrated circuit processing defects may cause changes in the value of the quiescent power supply current. Not all of these changes are detectable using classical functional testing techniques. Testing techniques based on the quiescent power supply current inspection have been reported to be efficient in the detection of a wide set of well known physical defects (including bridges and stuck-on). Two quiescent current sensor circuits are proposed and discussed. These circuits are oriented to different testing applications, as the external functional ATE environment, and the built-in self-testing (BIST) design for both on-line and off-line strategies.
    Add to favourites
    Export citations
Kramers-Kronig relations for nonlinear optics
New distributed package model for the dual gate FET
Performance improvement of output feedback control systems using the theory of variable structure systems
Linear approximation of fractional transfer functions of distributed parameter systems
Model reduction by least-squares moment matching
Comment: New class of codes suitable for computer error control
Method of null steering in phased array antenna systems
  • Author(s): B.E. Stuckman  and  J.C. Hill
  • Source: Electronics Letters, Volume 26, Issue 15, p. 1216 –1218
  • DOI:  10.1049/el:19900786
  • Type: Article
  • + Show details - Hide details
  • p. 1216 –1218 (3)
    A method for calculating current distributions on a phased array antenna is presented. The method produces steerable major lobes for transmission purposes and multiple independently steerable nulls for rejection of unwanted signals during transmission. The method allows fine tuning of the nulls based upon a set of linear equations and is ideally suited to the implementation of vertical phased array antenna systems operating in the HF frequency spectrum. Several examples are presented.
    Add to favourites
    Export citations
Characterisation of diode-pumped erbium-doped fluorozirconate fibre optical amplifier
Robust model reference adaptive control algorithm for a class of plants with bounded input disturbances

Most viewed content for this Journal

Article
content/journals/el
Journal
5
Loading

Most cited content for this Journal

Print this page
This is a required field
Please enter a valid email address