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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 22, Issue 9, 24 April 1986

Volumes & issues:

Volume 22, Issue 9

24 April 1986

Capacity estimation of cellular mobile radio systems
  • Author(s): M. Hata  and  M. Sakamoto
  • Source: Electronics Letters, Volume 22, Issue 9, p. 449 –450
  • DOI:  10.1049/el:19860305
  • Type: Article
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  • p. 449 –450 (2)
    A capacity estimation procedure for cellular systems is introduced under a condition of concentrated traffic distribution. Comparisons are made of systems with 12.5 kHz and 25 kHz channel spacing to clarify the difference in system capacity for uniform and concentrated traffic distribution conditions. The results show it is necessary to take actual traffic distribution conditions into account in making system capacacity estimations.
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Power penalty due to decision-time jitter in optical communication systems
  • Author(s): G.P. Agrawal  and  T.M. Shen
  • Source: Electronics Letters, Volume 22, Issue 9, p. 450 –451
  • DOI:  10.1049/el:19860306
  • Type: Article
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  • p. 450 –451 (2)
    The effect of decision-time jitter on the performance of optical communication systems is evaluated theoretically. The jitter-induced noise and the associated power penalty are calculated for the uniform and Gaussian distributions of the time jitter. The results suggest that the time jitter should be ≲(4B)−1 to keep the power penalty below 1 dB for a light-wave system operating at a bit rate B.
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DC fibre-optic accelerometer with sub-μg sensitivity
Characterisation of frequency response of 1.5 μm InGaAsP DFB laser diode and InGaAs PIN photodiode by heterodyne measurement technique
  • Author(s): R. Schimpe ; J.E. Bowers ; T.L. Koch
  • Source: Electronics Letters, Volume 22, Issue 9, p. 453 –454
  • DOI:  10.1049/el:19860308
  • Type: Article
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  • p. 453 –454 (2)
    The frequency response of an InGaAs PIN photodiode and the ratio of the frequency modulation (FM) index to the intensity modulation (IM) index of a 1.5 μm InGaAsP vapour-phase-transported DFB laser diode have been measured by an optical heterodyne measurement technique. From the response of the photodiode to the laser radiation beat frequency, a 20 GHz detector bandwidth is determined. The ratio of the FM and IM indices at 3 mW laser output power per facet decreases from 60 at 100 MHz modulation frequency to 3.3 above 2 GHz.
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Integrated laser/phototransistor optoelectronic switching device by organometallic vapour phase epitaxy
  • Author(s): C.F. Schaus ; J.R. Shealy ; F.E. Najjar ; F.L. Eastman
  • Source: Electronics Letters, Volume 22, Issue 9, p. 454 –456
  • DOI:  10.1049/el:19860309
  • Type: Article
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  • p. 454 –456 (3)
    Computer-controlled organometallic vapour phase epitaxy has been used to optimise AlGaAs/GaAs quantum well lasers and bipolar phototransistors separately. Here the two structures are combined In a single growth to realise a high-performance two-terminal optoelectronic switch. DC I/V characteristics are typical of an npnp structure; however, the feedback mechanism is optical rather than electronic. Threshold switching voltage is determined by the optical input in the range 1.3–23 V and sensitivity is 2.5 V/μW. Output is both optical (laser) and electrical current. Gain is provided by the phototransistor and optical feedback and exceeds 104. Switching speed is determined to be less than 1 ns.
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Dual-frequency modified C/V technique
  • Author(s): L.F. Lønnum  and  J.S. Johannessen
  • Source: Electronics Letters, Volume 22, Issue 9, p. 456 –457
  • DOI:  10.1049/el:19860310
  • Type: Article
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  • p. 456 –457 (2)
    A technique is presented which allows the carrier density profile to be obtained from very leaky Schottky-barrier devices. Measurements of the impedance as a function, of applied reverse voltage for two frequencies are combined to yield the depletion layer capacitance, along with expressions for the parasitic series and shunt resistances. The technique is easily extendable to MOS devices.
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Dynamic intensity noise and related gain compression phenomena for a GaAlAs BH laser
Generation of simple limit cycles in digital circuits
Second harmonic generation from LB superlattices containing two active components
  • Author(s): D.B. Neal ; M.C. Petty ; G.G. Roberts ; M.M. Ahmad ; W.J. Feast ; I.R. Girling ; N.A. Cade ; P.V. Kolinsky ; I.R. Peterson
  • Source: Electronics Letters, Volume 22, Issue 9, p. 460 –462
  • DOI:  10.1049/el:19860313
  • Type: Article
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  • p. 460 –462 (3)
    Second harmonic generation has been observed from Langmuir-Blodgett multilayer arrays containing two active components. Both materials were based on long chain donor-acceptor dye compounds, but were designed with the donor-acceptor groups in opposite senses with respect to the hydrocarbon chain. Preliminary results indicate a significant enhancement of the second-order polarisability for this type of supermolecular array.
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High-efficiency operation of phase-adjusted DFB laser by asymmetric structure
Performance of star microstrip as a linearly and circularly polarised TM2,1 mode radiator
High-power and high-efficiency phased array lasers grown by a two-step metalorganic chemical vapour deposition
Using non-Fourier techniques in signal processing for AN FMCW hidden-object detection radar
Formation of multilayer Si3N4 structures by nitrogen ion implantation
  • Author(s): K.J. Reeson ; P.L.F. Hemment ; R.F. Peart ; C.D. Meekison ; G.R. Booker ; J. Davis
  • Source: Electronics Letters, Volume 22, Issue 9, p. 467 –469
  • DOI:  10.1049/el:19860318
  • Type: Article
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  • p. 467 –469 (3)
    Buried double-layered nitride structures in single-crystal (100) silicon have been produced by the implantation of doses of 0.75 × 1018 N+ cm-2 at 350 keV and 200 keV, respectively. Observations by RBS and channelling on the structure before and after high-temperature annealing and by TEM after annealing have shown two distinct buried nitride layers of different thicknesses. The mechanisms responsible for the formation of such a structure are discussed, together with possible routes for nitrogen migration. The processing conditions to form multilayer structures which are suitable for device applications are proposed.
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Wide-range directional LDV employing modulated semiconductor laser source
  • Author(s): J.E. Schrøder  and  C.J. Nielsen
  • Source: Electronics Letters, Volume 22, Issue 9, p. 469 –470
  • DOI:  10.1049/el:19860319
  • Type: Article
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  • p. 469 –470 (2)
    A laser Doppler velocimeter (LDV) based on a semiconductor laser is described. Information on the direction of flow is obtained by applying a single-sideband technique using direct modulation of the laser diode. A measuring range of 8.4 MHz is reached with this technique, where the nonideal FM properties of the semiconductor laser are dealt with by an equalisation of the modulation current.
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Improved sequential linear prediction by selective time-domain coefficient extraction
Planar VPE infill 1.3 μm integrated laser/monitor photodiode with CARIBE etched facets
Suppression of stimulated Brillouin scattering in a single-mode fibre by an acousto-optic modulator
  • Author(s): M. Tsubokawa ; S. Seikai ; T. Nakashima ; N. Shibata
  • Source: Electronics Letters, Volume 22, Issue 9, p. 473 –475
  • DOI:  10.1049/el:19860322
  • Type: Article
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  • p. 473 –475 (3)
    Stimulated Brillouin scattering in a single-mode optical fibre was fully suppressed by launching two frequency beams passed through an acousto-optic modulator. A suppression ratio up to 30 dB was obtained for a frequency difference of 500 MHz between two beams. The experimental result agrees with the theoretical estimation. The method has great advantages for optical fibre systems using a continuous high-power laser source.
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Anomalous length dependence of threshold for thin quantum well AlGaAs diode lasers
  • Author(s): P.S. Zory ; A.R. Reisinger ; L.J. Mawst ; G. Costrini ; C.A. Zmudzinski ; M.A. Emanuel ; M.E. Givens ; J.J. Coleman
  • Source: Electronics Letters, Volume 22, Issue 9, p. 475 –476
  • DOI:  10.1049/el:19860323
  • Type: Article
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  • p. 475 –476 (2)
    The threshold current in conventional semiconductor diode lasers decreases linearly with decreasing cavity length. We have found that for AlGaAs diode lasers fabricated from very thin active layer material, the threshold current can be essentially constant over a wide range of cavity lengths. At short cavity lengths, threshold increases dramatically. This anaomalous behaviour is attributed to physical mechanisms which become important when active layer threshold gain requirements become unusually high.
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New way of plotting current/voltage characteristics of Schottky diodes
  • Author(s): M. Missous  and  E.H. Rhoderick
  • Source: Electronics Letters, Volume 22, Issue 9, p. 477 –478
  • DOI:  10.1049/el:19860324
  • Type: Article
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  • p. 477 –478 (2)
    It is pointed out that the empirical diode relationship I = I0 exp (qV/nkT){1 - exp (-qV/kT)} has the property that a plot of log [I/{1 - exp (-qV/kT)}] against V should be linear for all values of V, including reverse voltages. This equation has been tested by making such a plot for an Al/GaAs Schottky diode made by MBE. The plot is linear over the entire range from +0.5 V to - 1.0 V, with n = 1.01.
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Design technique to reduce effects of tidal variations on an ILS glide slope system
  • Author(s): V. Ungvichian
  • Source: Electronics Letters, Volume 22, Issue 9, p. 478 –479
  • DOI:  10.1049/el:19860325
  • Type: Article
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  • p. 478 –479 (2)
    A 330 MHz null-reference glide slope system design technique to minimise the reflecting surface variations is introduced. The runaway approach end of the site selected to test this design is over an ocean. Since the ocean forms part of the reflecting surface of the glide slope system, the tidal variations will affect the glide angle. The uniform theory of diffraction is used in the analysis and calculations are made for five tidal levels from high to low tide. The results of the simulations indicate that a glide path angle exists which is least sensitive to the tidal variations. Furthermore, this optimum angle provides smooth glide path structure.
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Two-way transmission using electro-optical modulator
Integrated travelling-wave antenna for nonradiative dielectric waveguide
Edge extraction by a class of second-order nonlinear filters
Dry etching characteristics of LiNbO3
Broadband lumped equivalent circuit for shunt-connected radial stub
Low-noise microwave HIFET fabricated using photolithography and MOCVD
Fibre Brillouin amplifier with electronically controlled bandwidth
Equidistant linear phase functions with improved selectivity and stopband attenuation
  • Author(s): M.P. Barros  and  L.F. Lind
  • Source: Electronics Letters, Volume 22, Issue 9, p. 490 –491
  • DOI:  10.1049/el:19860333
  • Type: Article
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  • p. 490 –491 (2)
    The letter describes a technique to manipulate the parameters governing Rhodes equidistant linear phase functions, so that two finite transmission-zero pairs can appear on the imaginary axis of the complex plane. An increase in the amplitude selectivity and stopband attenuation occurs, with little degradation of the passband ripple and group delay, especially for higher-degree transfer functions.
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High-speed and high-coding-gain Viterbi decoder with low power consumption employing SST (scarce state transition) scheme
As- and Ga-implanted silicon camel diodes
Coherent backscatter-induced drift in phase-modulated optical fibre gyroscopes
  • Author(s): I.P. Giles ; J. Mackintosh ; J. McMillan ; B. Culshaw
  • Source: Electronics Letters, Volume 22, Issue 9, p. 494 –496
  • DOI:  10.1049/el:19860336
  • Type: Article
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  • p. 494 –496 (3)
    The rotation rate measurement error produced by back-scatter from a partially coherent source has been investigated. The level of error introduced is shown to be dependent on the phase-modulation frequency. Operation at the correct frequency completely eliminates the coherent backscatter-induced errors. Taking into consideration realistic modulator stability conditions a source with a coherence length of tens of centimetres is feasible in an inertial grade, phase-modulated system.
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Closed-tube diffusion of silicon in GaAs from sputtered silicon film
  • Author(s): E. Omura ; X.S. Wu ; G.A. Vawter ; L. Coldren ; E. Hu ; J.L. Merz
  • Source: Electronics Letters, Volume 22, Issue 9, p. 496 –498
  • DOI:  10.1049/el:19860337
  • Type: Article
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  • p. 496 –498 (3)
    Silicon diffusion into GaAs from a sputtered film in a closed ampoule is described. Excess arsenic pressure is required in the ampoule for a successful diffusion. The relationship between junction depth and the diffusion coefficient has been theoretically derived and the activation energy of the Si-Si pair diffusion coefficient has been obtained from that relation.
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Method for the detection of small changes in the sampling rate of a data acquisition system
Gate propagation delay and logic timing of GaAs integrated circuits measured by electro-optic sampling
High-speed response characteristics of GaAs optoelectronic integrated receivers
  • Author(s): H. Hamaguchi ; M. Makiuchi ; O. Wada
  • Source: Electronics Letters, Volume 22, Issue 9, p. 501 –502
  • DOI:  10.1049/el:19860340
  • Type: Article
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  • p. 501 –502 (2)
    The letter focuses on the measurement of pulse response characteristics of an optoelectronic integrated receiver in which a GaAs metal-semiconductor-metal (MSM) photodiode and a GaAs field-effect transistor amplifier are monolithically integrated on a GaAs substrate. The maximum parasitic capacitance was found to be negligible for the total capacitance at the amplifier input. We also verified a fast response of this receiver showing a rise time of 300 ps.
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Ka-band monolithic gain control amplifier
Erratum: Improved systolic array for linear discriminant function classifier
Erratum: Fully differential bilinear integrator for SC filters

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