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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 21, Issue 10, 9 May 1985

Volumes & issues:

Volume 21, Issue 10

9 May 1985

Ultra-high doping levels of GaAs with beryllium by molecular beam epitaxy
Approximation errors in the computation of Cheby̅shev expansion coefficients
Fibre-optic polarising beam splitter employing birefringent-fibre coupler
  • Author(s): I. Yokohama ; K. Okamoto ; J. Noda
  • Source: Electronics Letters, Volume 21, Issue 10, p. 415 –416
  • DOI:  10.1049/el:19850295
  • Type: Article
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  • p. 415 –416 (2)
    An in-line fibre-optic polarising beam splitter, consisting of a fused birefringent-fibre coupler, is reported. Splitting of the orthogonally polarised lights was accomplished by increasing the difference of coupling ratios for the two polarisation modes. When a light at 1.402 μm wavelength was coupled to the input lead, each polarisation was split on to different output leads, showing extinction ratios of more than 17 dB in both leads.
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Ultra-low-noise, high-impedance preamp for cryogenic detectors
High-power single-mode optical-fibre coupling to InGaAsP 1.3 μm mesa-structure surface-emitting LEDs
Wideband and high-gain negative-feedback AGC amplifier for high-speed lightwave digital transmission systems
Dynamic channel allocation schemes for cordless telephones
On-chip switching for DC parametric testing
Broad-passband-width optical filter for multi/demultiplexer using a diffraction grating and a retroreflector prism
Inversion algorithm to construct Routh approximants
Substrate influence on flat folded dipole bandwidth
Measurement of Gaussian beam diameter using ronchi rulings
Platinum intermetallic resistors for GaAs-based circuits
  • Author(s): S. Tiwari  and  W.H. Price
  • Source: Electronics Letters, Volume 21, Issue 10, p. 429 –430
  • DOI:  10.1049/el:19850305
  • Type: Article
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  • p. 429 –430 (2)
    A simple technique for making intermetallic resistors of sheet resistance around 25 Ω/□ is described. The resistors were formed by reacting a 300 Å film of platinum with underlying GaAs to completion. PtGa, PtGa2 and PtAs2 phases were identified in the temperature range of 450°C to 550°C investigated. The temperature coefficient of resistivity was of the order of +9.2×10−4°C−1 at 25°C and the resistors appeared to be stable up to current densities of 105 A/cm2.
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Improved switched-capacitor algorithmic analogue-to-digital convertor
Determination of P-adic transform bases and lengths
Improved method of controlling stepping motor switching angle
OFDR diagnostics for fibre and integrated-optic systems
Optical system for real-time processing of multiple matrix product
  • Author(s): H. Nakano  and  K. Hotate
  • Source: Electronics Letters, Volume 21, Issue 10, p. 435 –437
  • DOI:  10.1049/el:19850310
  • Type: Article
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  • p. 435 –437 (3)
    A novel optical system for real-time processing of a multiple matrix product is proposed. In this system, there is no scanning mechanism, and all of the N×N matrices to be multiplied have the N2 format. This system can easily be extended to that for multiplication of more than three matrices using a holographic unidirectionally diffusing screen. The preliminary experiments of multiplying three matrices based on this system is successfully demonstrated with a mean error of 4.7%.
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Broadband circularly polarised planar array composed of a pair of dielectric resonator antennas
Photobleaching effect on visible-region loss increase for heat-treated optical fibres in a hydrogen atmosphere
Dielectric switching with memory in thin films of stearic acid
InGaAs photodiodes prepared by low-pressure MOCVD
  • Author(s): P. Poulain ; M. Razeghi ; K. Kazmierski ; R. Blondeau ; P. Philippe
  • Source: Electronics Letters, Volume 21, Issue 10, p. 441 –442
  • DOI:  10.1049/el:19850314
  • Type: Article
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  • p. 441 –442 (2)
    InGaAs/InP double-heterostructure PIN photodiodes are demonstrated using the low-pressure MOCVD growth technique. Several types of detectors are reported, ranging from small-area ones suitable for PINFET implementation to broad-area general-purpose devices for both long- and short-wavelength applications. These diodes have performances equivalent to those obtained when using conventional growth techniques.
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Switched predictor adaptation of DPCM-AQB speech coder using an imbedded vector quantisation
  • Author(s): V. Ramamoorthy
  • Source: Electronics Letters, Volume 21, Issue 10, p. 442 –444
  • DOI:  10.1049/el:19850315
  • Type: Article
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  • p. 442 –444 (3)
    An adaptive differential pulse-code-modulation speech coder with a switched predictor adaptation scheme is described. The predictor adaptation is done by switching one of the several predetermined predictors stored both at the encoder and the decoder. The selection of the predictor is controlled by a vector quantiser. The tradeoff between the performance and the extra side information that needs to be transmitted is evaluated for bit rates of 16, 24 and 32 Kbit/s.
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Software distribution via broadcast television signals
  • Author(s): J. Billingsley  and  R.J. Billingsley
  • Source: Electronics Letters, Volume 21, Issue 10, p. 444 –445
  • DOI:  10.1049/el:19850316
  • Type: Article
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  • p. 444 –445 (2)
    A method is described for the transmission of software and digital data at rates of multiples of 500 baud as part of a broadcast television signal. Unlike teletext-based systems, this method enables signals to be recorded on a domestic video recorder for subsequent decoding. The receiver interface is also much simpler, consisting of low-cost, commonplace components in a configuration which can be assembled by novices.
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Two-dimensional probability distribution of attenuation and depolarisation on Earth-space path
  • Author(s): H. Fukuchi
  • Source: Electronics Letters, Volume 21, Issue 10, p. 445 –447
  • DOI:  10.1049/el:19850317
  • Type: Article
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  • p. 445 –447 (3)
    Two-dimensional probability distribution of attenuation and crosspolarisation discrimination (XPD) on Earth-space path at 19.5 GHz (circular polarisation) is derived. Moreover, the distribution is approximated by a mathematical function. The distribution is compared with the theoretical relationship between rain-induced attenuation and XPD, which is based on the deformed raindrop model. It is found that the measured attenuation and XPD values are distributed two-dimensionally in an attenuation-XPD plane, and the results cannot be explained by the theoretical relationship. This fact implies that special attention should be paid when the XPD statistics on the Earth-space path are predicted by the theoretical relationship between attenuation and XPD.
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Planar InGaAs PIN photodiode with a semi-insulating InP cap layer
Selectively implanted oxygen isolation technology (SIO)
  • Author(s): P. Ratnam  and  C.A.T. Salama
  • Source: Electronics Letters, Volume 21, Issue 10, p. 448 –449
  • DOI:  10.1049/el:19850319
  • Type: Article
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  • p. 448 –449 (2)
    A new isolation technology using selectively implanted oxygen into silicon is presented. The technique offers a five-fold reduction in the bird's beak as compared to the standard LOCOS process. Good interface characteristics are observed for the implanted oxide as well as for the active oxide grown between the implanted oxide regions. Electrical characteristics of n+/p diodes isolated by the implanted oxide are found to be comparable to that of LOCOS diodes.
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InGaAs junction FETs with frequency limit (MAG = 1) above 30 GHz
  • Author(s): R. Schmitt  and  K. Heime
  • Source: Electronics Letters, Volume 21, Issue 10, p. 449 –451
  • DOI:  10.1049/el:19850320
  • Type: Article
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  • p. 449 –451 (3)
    InGaAs JFETs were made by LPE growth of the n-channel and zinc diffusion from spin-on films at low temperatures for the p+-gate. Extrinsic transconductances in excess of 100 mS/mm for gate lengths of 1.2 μm and frequency limits (MAG = 1) above 30 GHz were obtained. The good agreement between experimentally determined data and those calculated from material parameters and device dimensions indicates that a low temperature and/or short time process for gate formation is a necessary prerequisite in InGaAs JFET technology.
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Nonequilibrium devices for infra-red detection
Variable-length shift register
New ν(E) relationship for GaAs
  • Author(s): Y.-K. Feng
  • Source: Electronics Letters, Volume 21, Issue 10, p. 453 –454
  • DOI:  10.1049/el:19850323
  • Type: Article
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  • p. 453 –454 (2)
    A new ν(E) relationship of GaAs has been developed, in which the nonequilibrium transport effects (or velocity overshoot effects) of electrons were included. It was observed that the peak electric field Ep, corresponding to the average peak electron velocity νp, and the saturation electron velocity νs increase with shortening of the length of GaAs devices, and that Ep decreases slightly with the decrease of the lattice temperature To.
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