Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 11, Issue 15, 24 July 1975
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Volume 11, Issue 15
24 July 1975
Electro-optic technique for adding binary numbers
- Author(s): H.F. Taylor
- Source: Electronics Letters, Volume 11, Issue 15, p. 313 –314
- DOI: 10.1049/el:19750240
- Type: Article
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–314
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A new type of device that makes use of electro-optic modulation of light in dielectric waveguides for adding binary numbers is described. Only one logic element (an analogue comparator) is needed for each bit in the sum. Improved speed is a potential advantage of the electro-optic technique, since the number of sequential logic steps is considerably smaller than in conventional electronic adders.
Effect of dual implants into GaAs
- Author(s): T. Ambridge ; R. Heckingbottom ; E.C. Bell ; B.J. Sealy ; K.G. Stephens ; R.K. Surridge
- Source: Electronics Letters, Volume 11, Issue 15, p. 314 –315
- DOI: 10.1049/el:19750241
- Type: Article
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p.
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–315
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Enhanced donor activities have been obtained after annealing at 700°C for selenium implants into GaAs by implanting an equal dose of gallium together with the selenium. Donor concentration depth profiles, measured for both single and dual implants of 1×1013/cm2 and 2×1014/cm2 indicated that the increase in activity was mainly due to an increase in peak donor concentration for the dual implants compared with those measured for single implants.
New squared-magnitude function for digital bandpass filters
- Author(s): S.N. Hazra
- Source: Electronics Letters, Volume 11, Issue 15, p. 315 –316
- DOI: 10.1049/el:19750242
- Type: Article
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p.
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–316
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The skirt selectivities at the two ends of the passband of a usual digital bandpass filter may differ considerably if the passband is not symmetrically placed in the baseband. For such cases, a new magnitude function having better frequency characteristics is presented.
Equal-areas rule for gallium-arsenide avalanche diodes
- Author(s): J.E. Carroll and B. Culshaw
- Source: Electronics Letters, Volume 11, Issue 15, p. 316 –318
- DOI: 10.1049/el:19750243
- Type: Article
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–318
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The equal-areas rule is well known in the theory of Gunn diodes. It has recently been proposed that the rule be extended to gallium-arsenide IMPATTS. The letter shows that the equal-areas rule, in a slightly modified form, may be applied to carrier transport in avalanche diodes. This form of the rule may be applied to silicon and gallium-arsenide devices, and is the basis of a striking contrast between the two materials.
Eigenvalue assignment by reduced-order models
- Author(s): J. Hickin and N.K. Sinha
- Source: Electronics Letters, Volume 11, Issue 15, p. 318 –319
- DOI: 10.1049/el:19750244
- Type: Article
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–319
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A method combining model reduction and aggregation has been suggested as a means of assigning prescribed values to a subset of the eigenvalues of a linear fixed control system. This method is generalised to include all projective model reduction techniques and approximate eigenvalue assignment by output feedback.
Planar Gunn-effect logic device with two separated cathodes
- Author(s): M. Masuda ; M. Nishida ; M. Kimura ; J. Koyama
- Source: Electronics Letters, Volume 11, Issue 15, p. 320 –321
- DOI: 10.1049/el:19750245
- Type: Article
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Experimental results are presented for fundamental logic performances in a planner Gunn-effect device with two separated cathodes, which was fabricated on an epitaxial GaAs grown on a semi-insulating substrate. By selecting the polarity of input trigger pulses with respect to that of the biasing voltage, two functions, exclusive-OR (comparator) and inclusive-OR can be realised, as found by our computer simulation.
Leaky modes in graded fibres
- Author(s): W.J. Stewart
- Source: Electronics Letters, Volume 11, Issue 15, p. 321 –322
- DOI: 10.1049/el:19750246
- Type: Article
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–322
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Leaky modes, particularly tunnelling leaky modes, in step-index fibres are well known, but they are also present in graded fibres, in which case they are much more likely to cause errors in calculations and measurements, for example, transmission measurements, since they cannot be distinguished by any simple means from bound modes. The possible and probable extent of their effects are calculated by simple mode theory.
Encapsulation of ion-implanted GaAs using native oxides
- Author(s): B.J. Sealy and A.D.E. D'Cruz
- Source: Electronics Letters, Volume 11, Issue 15, p. 323 –324
- DOI: 10.1049/el:19750247
- Type: Article
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p.
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–324
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It was found that oxidation at 500 to 600°C produced uniform layers, which, when used as protective coatings for ion-implanted GaAs, gave rise to donor activity, but with poor reproducibility. The addition of a thin layer of evaporated aluminium to the oxide layer gave donor activities very similar to results obtained with other coating materials and with good reproducibility.
Minimal realisation of a symmetric transfer function matrix using Markov parameters and moments
- Author(s): R. Parthasarathy and H. Singh
- Source: Electronics Letters, Volume 11, Issue 15, p. 324 –326
- DOI: 10.1049/el:19750248
- Type: Article
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–326
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An algorithm for determining a minimal realisation from a symmetric transfer function matrix using a combination of Markov parameters and moments has been proposed. The procedure seems preferable for the problem of identification, when only a few Markov parameters are available.
Optimum criteria for output interfaces in digital stochastic computers
- Author(s): A.J. Miller ; A.W. Brown ; P. Mars
- Source: Electronics Letters, Volume 11, Issue 15, p. 326 –327
- DOI: 10.1049/el:19750249
- Type: Article
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p.
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–327
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Optimum criteria are discussed for the evaluation of output interface systems in digital stochastic computers. In particular, the ideal probability sensing, device is described, as well as a practical realisation of a variable-accuracy averager.
Extremely high packaging densities by operating integrated circuits with r.f. power
- Author(s): G. Krause
- Source: Electronics Letters, Volume 11, Issue 15, p. 327 –328
- DOI: 10.1049/el:19750250
- Type: Article
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p.
327
–328
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A binary circuit configuration in which the transistors operate with r.f. power is described. This mode of operation allows the use of very simple circuitry. I.C. configurations in which this principle is exploited to maximum advantage are proposed.
Effects of shape and orientation of spheroidal raindrops on microwave scattering
- Author(s): C. Warner
- Source: Electronics Letters, Volume 11, Issue 15, p. 328 –330
- DOI: 10.1049/el:19750251
- Type: Article
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p.
328
–330
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Following the use of Waterman's theory for calculating cross-sections and depolarisation ratios of spheroidal raindrops at microwave frequencies, theoretical methods are described for generalising results to arbitrary shape and orientation of the drops, with a view to obtaining depolarisation and differential attenuation for forward and back scattering.
Counterexample in the least-squares inverse stabilisation of 2D recursive filters
- Author(s): Y. Genin and Y. Kamp
- Source: Electronics Letters, Volume 11, Issue 15, p. 330 –331
- DOI: 10.1049/el:19750252
- Type: Article
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p.
330
–331
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A counterexample is presented disproving the conjecture that the planar least-squares inverse of a 2-variable polynomial is devoid of zeros when both variables are inside or on the unit circle.
Dyadic approximation about a general frequency point
- Author(s): D.H. Owens
- Source: Electronics Letters, Volume 11, Issue 15, p. 331 –332
- DOI: 10.1049/el:19750253
- Type: Article
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p.
331
–332
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Recent results in the dyadic expansion of a general, square transfer-function matrix are used to extend the concepts of dyadic approximation about s=0 to the general case. The results make possible the systematic approximation of linear systems, while retaining an exact description of system behaviour at a known frequency of interest.
Radiation from bent optical waveguides
- Author(s): A.W. Snyder ; I. White ; D.J. Mitchell
- Source: Electronics Letters, Volume 11, Issue 15, p. 332 –333
- DOI: 10.1049/el:19750254
- Type: Article
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p.
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–333
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A simple method is presented for determining the radiation losses due to the bending of an optical waveguide. This method circumvents the use of continuous modes and reduces the problem to elementary antenna theory in which radiation is found from a known surface-current distribution. Practical results are given for the bent fibre of circular cross-section. i.e. a toroidal geometry, both for the HE11 mode and for rays in an overmoded fibre.
New method of continuously measuring differential capacitance changes
- Author(s): B.Z. Kalpan ; Y. Sagy ; D.M. Jacobson
- Source: Electronics Letters, Volume 11, Issue 15, p. 333 –334
- DOI: 10.1049/el:19750255
- Type: Article
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p.
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–334
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A new instrument has been developed which can resolve small capacitance changes and yet can respond to large capacitance changes linearly. Such a versatile instrument has important applications in a variety of physical measurements.
Real-time acousto-optical image conversion
- Author(s): B. Delannoy ; G. Thomin ; M. Moriamez
- Source: Electronics Letters, Volume 11, Issue 15, p. 334 –335
- DOI: 10.1049/el:19750256
- Type: Article
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–335
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We report a new means of visualising, in real time, the potential distribution induced by an ultrasonic wave on the surface of a piezoelectric quartz wafer. The absence of scanning and a shutter function make this new system an original acousto-optical component.
Descent algorithm for the optimisation of bilinear systems
- Author(s): D.H. Owens
- Source: Electronics Letters, Volume 11, Issue 15, p. 335 –336
- DOI: 10.1049/el:19750257
- Type: Article
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p.
335
–336
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A simple identity is given which forms the basis of a descent algorithm for the optimisation of bilinear systems with quadratic performance index. The technique does not require linearisation of the system equations.
Self resonance in foil inductors
- Author(s): R.J. Kemp ; P.N. Murgatroyd ; N.J. Walker
- Source: Electronics Letters, Volume 11, Issue 15, p. 337 –338
- DOI: 10.1049/el:19750258
- Type: Article
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p.
337
–338
(2)
Coils having aluminium-foil windings exhibit multiple self-resonant behaviour in the range 0.5–20 MHz. The dependence of resonance frequencies on number of turns is reported, and a lumped circuit model which accounts approximately for the effects is presented.
Hybrid parametric amplifier
- Author(s): C.S. Aitchison and A.S. Wong
- Source: Electronics Letters, Volume 11, Issue 15, p. 338 –339
- DOI: 10.1049/el:19750259
- Type: Article
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p.
338
–339
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The letter proposes a hybrid parametric amplifier in which the signal circuit is a travelling-wave structure and the idling circuit is resonant. A simple expression for the available gain per section is calculated together with typical circuit values.
Effect of temperature on the transient response of twisted nematic liquid-crystal films
- Author(s): H.A. Tarry
- Source: Electronics Letters, Volume 11, Issue 15, p. 339 –341
- DOI: 10.1049/el:19750260
- Type: Article
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p.
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–341
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The measured rise and decay times of biphenyl twisted nematic devices fall by factors greater than 10 over the range −10°C to +60°C. This is attributed to viscosity changes. The slow response at low temperatures is not improved by using eutectic mixtures with wider nematic ranges.
Design of multivariable control systems using reduced-order models
- Author(s): S.K. Woon and S.A. Marshall
- Source: Electronics Letters, Volume 11, Issue 15, p. 341 –342
- DOI: 10.1049/el:19750261
- Type: Article
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p.
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–342
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In designing multivariable control systems using reduced-order models it is shown that, provided certain properties are satisfied, the original model is closed-loop stable if the reduced model is likewise stable. The reduction procedure given is new and the design uses the inverse Nyquist array method.
Attenuation and phase distortion in lossy acoustic-surface-wave multistrip couplers
- Author(s): O. Schwelb and E.L. Adler
- Source: Electronics Letters, Volume 11, Issue 15, p. 342 –344
- DOI: 10.1049/el:19750262
- Type: Article
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342
–344
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An easy-to-use closed-form expression is reported which given the attenuation and the phase velocity of the acoustic-surface-wave eigenmodes of the uniform multistrip coupler consisting of resistive strips. A computer program has been written to implement the numerical calculation of output power, group delay and the sensitivity of output amplitude with respect to changes in the metallisation ratio.
Improvements in the beam-wave theory of the open resonator
- Author(s): A.L. Cullen
- Source: Electronics Letters, Volume 11, Issue 15, p. 344 –345
- DOI: 10.1049/el:19750263
- Type: Article
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p.
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–345
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It is shown that electromagnetic perturbation theory can be used to improve the well known beam-wave formula for the resonance frequency of an open resonator. A simple case has been worked out in detail. A connection between the perturbation method and a variational formula is indicated.
Bias-tuned double-drift impatt diodes for wide-bandwidth operation
- Author(s): R.S. Ying and D.H. Lee
- Source: Electronics Letters, Volume 11, Issue 15, p. 345 –346
- DOI: 10.1049/el:19750264
- Type: Article
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p.
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–346
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Double-drift IMPATT diodes with asymmetrical p- and n-type doping concentrations have exhibited output power levels of 3 mW to greater than 100 mW when bias tuned over a 20 GHz bandwidth in a Q band (40–60 GHz) reduced waveguide circuit. Similar output powers were also measured for the same asymmetrical diodes at V band (50–75 GHz) with tunable bandwidths of approximately 18 GHz.
Design techniques for stable model reference adaptive control systems
- Author(s): A.J. Udink Ten Cate
- Source: Electronics Letters, Volume 11, Issue 15, p. 347 –348
- DOI: 10.1049/el:19750265
- Type: Article
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p.
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–348
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A technique is presented for multivariable model reference adaptive control systems that are synthesised according to the second method of Lyapunov. Improved error convergence is obtained by the use of a function of the parameter misalignment.
Optics of propagation in the anisotropic space of an acoustic-surface-wave disc delay line
- Author(s): I.M. Mason ; E. Papadofrangakis ; J. Chambers ; R. Ulrich
- Source: Electronics Letters, Volume 11, Issue 15, p. 348 –349
- DOI: 10.1049/el:19750266
- Type: Article
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–349
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Anisotropy acts to select preferentially certain well defined beam trajectories on the surface of a disc delay line. Selection is ascribed to the curvature of the slowness surface. An anisotropic optical design formalism is developed and applied to the diagnosis of earlier experimental observations of large differences in loss on three rectangular recirculating loops.
Lightning-flash counter using pattern recognition to discriminate between ground and cloud flashes
- Author(s): D. MacKerras and T.L. Gillett
- Source: Electronics Letters, Volume 11, Issue 15, p. 350 –351
- DOI: 10.1049/el:19750267
- Type: Article
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Electric-field changes caused by lightning flashes have characteristic features related to the type of discharge involved, which have been used as the design basis of a discriminating lightning-flash counter. Provided that the overall magnitude of the electric-field change exceeds 230 V/m, the counter registers a ground flash if the largest positive step in the field change exceeds 0·25 of the overall magnitude, and a cloud flash otherwise. Preliminary results indicate that significantly better discrimination is achieved than in the CIGRE lightning-flash counter.
Caractérisation des noyaux de Volterra d'un systéme non lineaire (Characterisation of the Volterra kernels of a nonlinear system)
- Author(s): M. Gautier ; M. Monsion ; J.P. Sagaspe
- Source: Electronics Letters, Volume 11, Issue 15, p. 351 –353
- DOI: 10.1049/el:19750268
- Type: Article
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–353
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A procedure is described which allows the determination of the Volterra kernels of nonlinear systems. The output of each kernel is determined and a double decomposition on a set of orthonormal functions is used to identify the kernels
Indirect model-matching technique for multicontroller systems
- Author(s): S.G. Tzafestas
- Source: Electronics Letters, Volume 11, Issue 15, p. 353 –354
- DOI: 10.1049/el:19750269
- Type: Article
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–354
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An indirect state-feedback technique for matching a controllable multicontroller system to a given model is presented. By this technique the multicontroller system is transformed to its Asseo phase-variable canonical form prior to the application of the state-feedback control. The cases where the system under control and the model are equidimensional or not are considered, and a solution to the model-matching problem by using output feedback is provided. The theory is illustrated by three examples.
Novel inductorless neuristor line
- Author(s): B.M. Wilamowski ; Z. Czarnul ; M. Bialko
- Source: Electronics Letters, Volume 11, Issue 15, p. 355 –356
- DOI: 10.1049/el:19750270
- Type: Article
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A novel inductorless neuristor line having the desired properties of the axon is described. Each section of the line consists of a pair of p-n-p-n-p-n transistors and an RC circuit with small capacitor values. This allows integration of the line using semiconductor technology.
Erratum: Rectangular-ridge vibrational modes
- Author(s): T.M. Sharon ; A.A. Maradudin ; S.L. Cunningham
- Source: Electronics Letters, Volume 11, Issue 15, page: 356 –356
- DOI: 10.1049/el:19750271
- Type: Article
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