Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 17, Issue 20, 1 October 1981
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Volume 17, Issue 20
1 October 1981
Production of single-mode fibres with negligible intrinsic birefringence and polarisation mode dispersion
- Author(s): A.J. Barlow ; D.N. Payne ; M.R. Hadley ; R.J. Mansfield
- Source: Electronics Letters, Volume 17, Issue 20, p. 725 –726
- DOI: 10.1049/el:19810509
- Type: Article
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Spinning the preform during drawing produces a fibre with a permanent twist. It is shown that such a fibre has negligible polarisation birefringence and rotation. Polarisation mode dispersion is similarly reduced.
Mn as a p-type dopant in In0.53Ga0.47As on InP substrates
- Author(s): N. Chand ; P.A. Houston ; P.N. Robson
- Source: Electronics Letters, Volume 17, Issue 20, p. 726 –727
- DOI: 10.1049/el:19810510
- Type: Article
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Mn has been used as a p-type dopant in LPE In0.53Ga0.47As. The distribution coefficient was measured as 0.6 and the activation energy was 52.5±2.5 meV. The room temperature mobility varied from 183 to 94 cm2 V−1s−1 in the concentration range studied. A solid to solid diffusion coefficient of 2.6×10−12 cm2 s−1 was estimated for Mn into the substrate at 640°C.
New optical heterodyne detector with integrated diffraction grating
- Author(s): H. Sakaki ; Y. Fujii ; M. Misawa ; H. Hidaka
- Source: Electronics Letters, Volume 17, Issue 20, p. 727 –729
- DOI: 10.1049/el:19810511
- Type: Article
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A new optical heterodyne detector, consisting of a silicon photodiode and an integrated diffraction grating on the diode surface, is proposed and its successful operation is demonstrated. The detector is shown to be compact in structure and quite stable to mechanical misalignment with respect to incident optical waves.
Planar antennas on a dielectric surface
- Author(s): C.R. Brewitt-Taylor ; D.J. Gunton ; H.D. Rees
- Source: Electronics Letters, Volume 17, Issue 20, p. 729 –731
- DOI: 10.1049/el:19810512
- Type: Article
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A theory has been developed for planar metal antennas on a dielectric surface and the main predictions have been verified experimentally. Current dipole antennas have radiation diagrams and impedances favourable for microwave to far-infra-red integrated circuits.
VAD single-mode fibres with high Δn values
- Author(s): T. Tomaru ; M. Kawachi ; M. Yasu ; T. Miya ; T. Edahiro
- Source: Electronics Letters, Volume 17, Issue 20, p. 731 –732
- DOI: 10.1049/el:19810513
- Type: Article
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VAD single-mode fibres even with relative refractive-index difference Δn higher than 0.5% show low-loss properties, indicating the high potential of the VAD method to produce zero-dispersion fibres in the 1.55 μm wavelength region.
Method for improving microstrip coupler directivity
- Author(s): K. Shibata ; H. Yanagisawa ; Y. Torimura ; K. Hatori
- Source: Electronics Letters, Volume 17, Issue 20, p. 732 –733
- DOI: 10.1049/el:19810514
- Type: Article
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This letter describes a method for improving the directivity of the edge-coupled microstrip couplers; the coupler is made up of the suspended microstrip lines. The gap between the dielectric substrate and the ground plane is adjusted to get equal mode velocities under perfect matching conditions. Design data for optimum structure and experimental results are presented and discussed.
Efficient real-time interpolation for D/A conversion
- Author(s): J. de Carvalho and J.V. Hanson
- Source: Electronics Letters, Volume 17, Issue 20, p. 733 –735
- DOI: 10.1049/el:19810515
- Type: Article
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Four interpolation schemes using small sample sets are considered for real-time D/A conversion applications. Evaluation, for sampling rates near the Nyquist limit, is based on a mean-square-error criterion. Hardware suitability is considered with respect to the number of operations per interpolation and degree of parallelism.
Comment: New technique for determination of static emitter and collector series resistances of bipolar transistors
- Author(s): R.J. Hawkins
- Source: Electronics Letters, Volume 17, Issue 20, page: 735 –735
- DOI: 10.1049/el:19810516
- Type: Article
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Efficiency of loaded conical log-spiral antenna
- Author(s): P.A. Ramsdale
- Source: Electronics Letters, Volume 17, Issue 20, p. 735 –736
- DOI: 10.1049/el:19810517
- Type: Article
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The components of power radiated from a conical log-spiral antenna have been calculated. As the antenna is shortened it is no longer frequency independent and unwanted radiation components increase. Loading can be used to reduce these components but the load absorbs power. The resulting reduction in efficiency has been found.
Optimum directivity of elliptic loop antennas
- Author(s): D.K. Cheng and C.H. Liang
- Source: Electronics Letters, Volume 17, Issue 20, p. 736 –738
- DOI: 10.1049/el:19810518
- Type: Article
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The directivity of an elliptic loop antenna having a given perimeter and made of a conducting wire of a given radius is maximised with respect to the minor-axis/major-axis ratio, ζ. It is found that a circular loop does not yield a maximum directivity and that the value of ζ at which maximum directivity occurs depends on the perimeter.
GaAs power MESFETs prepared by metalorganic chemical vapour deposition
- Author(s): T. Shino ; S. Yanagawa ; Y. Yamada ; K. Arai ; K. Kamei ; T. Chigira ; T. Nakanisi
- Source: Electronics Letters, Volume 17, Issue 20, p. 738 –739
- DOI: 10.1049/el:19810519
- Type: Article
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GaAs power MESFETs have been developed by using MOCVD wafers. The saturation current of 7.2 mm-wide MESFET chips fabricated on a 6 cm2 wafer has been found to have a standard deviation of 6.8%, which is nearly a half of that observed for MESFETs fabricated on a conventional VPE wafer of the same size. The two-chip device with a gate width of 14.4 mm delivered 4 W at 7.8 GHz with 3 dB gain. The output power of 4 W at 7.8 GHz is the state-of-the-art performance of the GaAs power MESFETs prepared by the MOCVD technique.
Wideband tunable mm-wave Gunn oscillator design
- Author(s): M.J. Lazarus ; F.R. Pantoja ; S. Novak ; M.G. Somekh
- Source: Electronics Letters, Volume 17, Issue 20, p. 739 –741
- DOI: 10.1049/el:19810520
- Type: Article
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A new method of design of mm-wave Gunn oscillators has been developed and tested. The method utilises the fact that high frequency GaAs Gunn diodes work in the harmonic mode for transmission whilst allowing tuning at the fundamental. Hardware for wide frequency coverage (30 GHz centred at about 85 GHz) is described with experimental results.
Bistable operation of semiconductor lasers by optical injection
- Author(s): H. Kawaguchi
- Source: Electronics Letters, Volume 17, Issue 20, p. 741 –742
- DOI: 10.1049/el:19810521
- Type: Article
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Bistable operation in InP/InGaAsP DH lasers by optical injection is reported for the first time. An incident optical beam, generated by a conventional DH semiconductor laser, was injected into the semiconductor laser with inhomogeneous excitation. Bistability has been achieved in the relation between input intensity of the incident beam and the optical output intensity of the inhomogeneously excited laser. The bistable laser also acts as an optical limiter, i.e. the optical output completely saturates above the laser threshold level.
High-resolution measurement of diameter variations in optical fibres by the backscatter method
- Author(s): A.J. Conduit ; A.H. Hartog ; M.R. Hadley ; D.N. Payne ; M.P. Gold ; R.J. Mansfield ; E.J. Tarbox
- Source: Electronics Letters, Volume 17, Issue 20, p. 742 –744
- DOI: 10.1049/el:19810522
- Type: Article
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The backscatter signal measured with high resolution from optical fibres with complex diameter variations is shown to follow precisely the diameter profile. The local attenuation which is anticorrelated from opposite ends of the fibre is compared with a simple theoretical model.
High-efficiency millimetre-wave silicon impatt oscillators
- Author(s): H.S. Gokgor ; I. Davies ; A.M. Howard ; D.M. Brookbanks
- Source: Electronics Letters, Volume 17, Issue 20, p. 744 –745
- DOI: 10.1049/el:19810523
- Type: Article
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High-efficiency impatt devices and oscillators have been fabricated from epitaxially grown silicon for operation in the frequency range 40–140 GHz. These devices have produced world state-of-the-art efficiencies and demonstrated the expected relative frequency insensitivity of silicon. Single drift devices have given efficiencies of approximately 8%; and double drift device efficiencies as high as 13.5% at 50 GHz and 12% at 90 GHz. Initial measurements show that the sideband phase noise levels follow a constant deviation law.
Numerical simulation of solar cell open circuit voltage decay
- Author(s): L. Castañer ; J. Llabería ; J. Garrido ; E. Vilamajó
- Source: Electronics Letters, Volume 17, Issue 20, p. 745 –747
- DOI: 10.1049/el:19810524
- Type: Article
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A numerical simulation of the open circuit voltage decay of junction solar cells has been done including a double exponential model for DC I(V) characteristics and dynamic capacitive effects arising from quasineutral and space-charge regions
Determination of an initial mesh for computer simulation of H-abrupt devices
- Author(s): R.J. Bennett and K.A. Thoma
- Source: Electronics Letters, Volume 17, Issue 20, p. 747 –748
- DOI: 10.1049/el:19810525
- Type: Article
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A computer procedure to determine the initial potential distribution in the vicinity of semiconductor junction structures, in particular hyperabrupt ones, is outlined. The procedure has the advantage of cutting down on computation time, especially if high applied voltages are considered.
Improved conditional runlength codes based on two composite states
- Author(s): Y. Shim and J. Kim
- Source: Electronics Letters, Volume 17, Issue 20, p. 748 –749
- DOI: 10.1049/el:19810526
- Type: Article
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The performances of the conventional CRC (conditional runlength code) and CIRC (conditional incremental runlength code) are improved with some modifications in coding algorithm. These include ZOH (zero-order hold) prediction, modified line-termination, and classification of the incremental runs. Average gains of 15% and 9% are obtained in compression factor for the CRC and CIRC, respectively.
Cross-spectral densities of array elements for folded dipole and loop antennas
- Author(s): T.S.M. Maclean ; S.P.S. Saini ; Z. Barboza
- Source: Electronics Letters, Volume 17, Issue 20, p. 749 –751
- DOI: 10.1049/el:19810527
- Type: Article
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When a loop or folded dipole antenna is placed in a noise field the resultant mean-square noise current is a function of the cross-spectral densities between the different segments of the antenna. Earlier work on the evaluation of cross-spectral densities between the collinear segments of a dipole placed in an isotropic noise field is here extended to include the parallel and orthogonal segments of rectangular loop and folded dipole antennas.
Multichannel photon-counting backscatter measurements on monomode fibre
- Author(s): P. Healey
- Source: Electronics Letters, Volume 17, Issue 20, p. 751 –752
- DOI: 10.1049/el:19810528
- Type: Article
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The letter reports the use of a multichannel, photon-counting technique to observe Rayleigh backscattered signals in very long lengths of monomode fibre. The equipment may be used to measure splice losses and fibre attenuations at the operating wavelength of 1.32 μm.
Amorphisation and low temperature recrystallisation of InP
- Author(s): V.L. Wrick ; W.J. Choyke ; C.F. Tzeng
- Source: Electronics Letters, Volume 17, Issue 20, p. 752 –754
- DOI: 10.1049/el:19810529
- Type: Article
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Fe-doped semi-insulating samples of InP have been implanted at room temperature and liquid nitrogen temperature at 200 KV with phosphorous. A fluence of 5 × 1014/cm2 was sufficient to render the lattice amorphous as determined by Rutherford backscattering techniques. Successful reconstruction of the damaged lattice was achieved using a 400°C anneal for 24 h on samples implanted at liquid nitrogen temperatures.
Symbolic analysis of circuits containing active elements
- Author(s): J.B. Grimbleby
- Source: Electronics Letters, Volume 17, Issue 20, p. 754 –756
- DOI: 10.1049/el:19810530
- Type: Article
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A simple modification to Percival's two-graph method is described which allows circuits containing four-terminal infinite-gain voltage amplifiers to be analysed symbolically. The modified method is of more general application than the standard two-graph method which requires that the active devices be represented by voltage-controlled current sources.
Temperature dependence of the transferred electron threshold current in In1−xGaxAsyP1−y
- Author(s): K.C. Heasman ; J.R. Hayes ; A.R. Adams ; P.D. Greene
- Source: Electronics Letters, Volume 17, Issue 20, p. 756 –757
- DOI: 10.1049/el:19810531
- Type: Article
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The threshold current for transferred electron effects in In1−xGaxAsyP1−y (0.4 <y = 2.1x <0.9) has been found to increase on cooling from 300 K to 77 K at a rate which is only about one-third of the corresponding rate for GaAs. This suggests that alloy scattering remains effective at high fields.
Effects of heat treatment on noise spectrum in Au-InP Schottky barriers
- Author(s): J.M. Peransin ; M. Mesbah ; E. Groubert
- Source: Electronics Letters, Volume 17, Issue 20, p. 757 –758
- DOI: 10.1049/el:19810532
- Type: Article
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Measurements are reported on low frequency noise in Au-InP Schottky diodes after heating cycles. An 1/f noise component was dominant in annealing time range before 80 min. Observation of G-R noise spectra are achieved for long-term operations. Noise measurements between 77 K and 300 K have given the time constants and the activation energies of five trapping levels. The G-R processes are attributed to traps due to gold contamination in the depletion region.
Efficient fundamental frequency oscillation from millimetre-wave indium phosphide n+-n-n+ transferred electron oscillators
- Author(s): I.G. Eddison ; I. Davies ; P.L. Giles ; D.M. Brookbanks
- Source: Electronics Letters, Volume 17, Issue 20, p. 758 –760
- DOI: 10.1049/el:19810533
- Type: Article
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The letter describes the development of CW indium phosphide, transferred-electron oscillators (TEOs) with emphasis being place on the achievement of efficient operation in the millimetre-wave frequency range. Reasons are given for the choice of the n+-n-n+ epitaxial structure used, together with relevant material growth and characterisation details. A brief outline of the device fabrication technology is given before discussing oscillator performances. Results are presented for operating frequencies from 30 to 110 GHz which show that the three-layer indium phosphide device is capable of much higher conversion efficiencies than the equivalent gallium arsenide structure at frequencies above 40 GHz. From these figures it is concluded that indium phosphide will supplant gallium arsenide as a mm-wave TEO material.
Temperature effect on low threshold voltage ion-implanted GaAs MESFETs
- Author(s): S.J. Lee and C.P. Lee
- Source: Electronics Letters, Volume 17, Issue 20, p. 760 –761
- DOI: 10.1049/el:19810534
- Type: Article
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The temperature dependence of the characteristics of ion-implanted GaAs MESFETs has been studied. The observed effects are mainly due to the p-n-junction-loke interface between the channel active layer and the semi-insulatning substrate. Good agreement between theoretical calculations and the experimental results is obtained.
Interface states in MOSFETs due to hot-electron injection determined by the charge pumping technique
- Author(s): D. Schmitt and G. Dorda
- Source: Electronics Letters, Volume 17, Issue 20, p. 761 –763
- DOI: 10.1049/el:19810535
- Type: Article
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The charge pumping technique is used to characterise interface states in MOSFETs created by hot-electron injection. Donor states near the middle of the bandgap are identified. Two independent methods to determine the location of these states are presented.
GaAs digital integrated circuits for very high-speed frequency division
- Author(s): M. Gloanec ; J. Jarry ; G. Nuzillat
- Source: Electronics Letters, Volume 17, Issue 20, p. 763 –765
- DOI: 10.1049/el:19810536
- Type: Article
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Dual- and single-clocked frequency dividers, consisting of normally-on GaAs MESFET integrated circuits, with maximum toggle frequency of 5.7 GHz, were fabricated. The gate length was 0.8 μm and an E-beam direct writing processing technology was used. Some improvements, such as reduction of the gate length and adoption of a double pinchoff voltage technology, would make possible the implementation of a counter family with a maximum operating frequency in the range 5–7 GHz.
Design of two-dimensional recursive digital filters to a specified stability margin
- Author(s): G. Crebbin and J. Attikiouzel
- Source: Electronics Letters, Volume 17, Issue 20, p. 765 –766
- DOI: 10.1049/el:19810537
- Type: Article
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A definition is given for a stability margin which can be applied to the computer-aided design of two-dimensional recursive digital filters. The Simplex method of function minimisation is proposed as a vehicle to implement this concept.
Leaky-mode channel-guide injection lasers
- Author(s): D.E. Ackley
- Source: Electronics Letters, Volume 17, Issue 20, p. 766 –768
- DOI: 10.1049/el:19810538
- Type: Article
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A new injection laser, the channel-guide (CG) laser, has been developed for leaky-mode operation. The devices are characterised by the stable, two-lobed far fields typical of leaky-mode operation and produce ‘kink-free’ outputs to > 160 mW (40 ns pulse) from a 3 μm stripe.
Materials dispersion zero in glass mixtures
- Author(s): K. Nassau
- Source: Electronics Letters, Volume 17, Issue 20, p. 768 –769
- DOI: 10.1049/el:19810539
- Type: Article
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Wemple's technique was used to calculate the wavelength of the material dispersion zero for mixtures. The SiO2-GeO2 calculations gave positive deviations from linearity, somewhat smaller than the limited experimental data available. The deviations were not symmetrical with composition, the dominant contribution to the skewness deriving from the reduced mass term.
Reduction of shot noise by the influence of space charge
- Author(s): A.H.W. Beck
- Source: Electronics Letters, Volume 17, Issue 20, p. 769 –771
- DOI: 10.1049/el:19810540
- Type: Article
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A theoretical expression for the space-charge reduction factor, valid to low microwave frequencies, is derived. Experiments which verify the result are described. The uses of the result as a possible diagnostic for cathode life are discussed.
Erratum: Encryption with keyed random permutations
- Author(s): F. Ayoub
- Source: Electronics Letters, Volume 17, Issue 20, page: 771 –771
- DOI: 10.1049/el:19810541
- Type: Article
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