Your browser does not support JavaScript!
http://iet.metastore.ingenta.com
1887
banner image
image of Volume 15, Issue 21
Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 15, Issue 21, 11 October 1979

Volumes & issues:

Volume 15, Issue 21

11 October 1979

Room-temperature c.w. operation of InP/InGaAsP/InP double heterostructure diode lasers emitting at 1.55 μm
  • Author(s): H. Kawaguchi ; K. Takahei ; Y. Toyoshima ; H. Nagai ; G. Iwane
  • Source: Electronics Letters, Volume 15, Issue 21, p. 669 –670
  • DOI:  10.1049/el:19790475
  • Type: Article
  • + Show details - Hide details
  • p. 669 –670 (2)
    Room-temperature c.w. operation has been achieved for stripe-geometry double heterostructure InP/InGaAsP/InP diode lasers emitting at 1.55 μm. The heterostructures were grown by l.p.e. on (100) InP substrates, and stripes were defined by the conventional planar-stripe structure. The room-temperature (20°C) c.w. threshold current ≃250 mA for a 6 μm wide by 200 μm long cavity.
    Add to favourites
    Export citations
Decoupled control of robot movement
  • Author(s): J.R. Hewit
  • Source: Electronics Letters, Volume 15, Issue 21, p. 670 –671
  • DOI:  10.1049/el:19790476
  • Type: Article
  • + Show details - Hide details
  • p. 670 –671 (2)
    Recently, methods have been proposed for the simultaneous decoupling of the controls of nonlinear dynamical systems and for the assignment of poles in the resulting decoupled linear systems. These methods have been used to obtain decoupled controls for the equations of motion of industrial robot arms and their performance has been gauged by simulation. It is shown here that such decoupling procedures do not guarantee stable controls and that their use, where the mathematical models of the controlled systems may be subject to uncertainty, should be attempted with caution.
    Add to favourites
    Export citations
Hybrid realisation of an adaptive filter for real-time noise-cancelling applications
  • Author(s): T. Schwarz  and  D. Malah
  • Source: Electronics Letters, Volume 15, Issue 21, p. 671 –672
  • DOI:  10.1049/el:19790477
  • Type: Article
  • + Show details - Hide details
  • p. 671 –672 (2)
    An efficient hybrid realisation of an adaptive filter for real-time noise-cancelling applications is described. The filter is based on an analogue tapped delay line but its coefficients are digital and are updated according to a simplified l.m.s. algorithm. A single multiplying d.a. device is used for performing the multiplications. The structure of the filter, its performance and processed examples are presented.
    Add to favourites
    Export citations
Adaptive filters to improve loudspeaker telephone
Improved ohmic properties of Au–Ge Contacts to thin n-GaAs layers alloyed with an SiO2 overlayer
Measurements performed on l.e.d. 4-level digital optical-fibre system for 68 Mbit/s
Strain birefringence in single-polarisation germanosilicate optical fibres
  • Author(s): I.P. Kaminow ; J.R. Simpson ; H.M. Presby ; J.B. MacChesney
  • Source: Electronics Letters, Volume 15, Issue 21, p. 677 –679
  • DOI:  10.1049/el:19790481
  • Type: Article
  • + Show details - Hide details
  • p. 677 –679 (3)
    Fibres that maintain a fundamental mode with fixed polarisation can be realised by the introduction of a large strain birefringence. A modal birefringence of 3 × 10−4 was achieved by differential thermal expansion in a germanosilicate fibre prepared from a circular preform by the exposed-cladding technique. Measurements of birefringence agree with earlier calculations.
    Add to favourites
    Export citations
Novel active RC circuit for floating-inductor simulation
  • Author(s): Raj Senani
  • Source: Electronics Letters, Volume 15, Issue 21, p. 679 –680
  • DOI:  10.1049/el:19790482
  • Type: Article
  • + Show details - Hide details
  • p. 679 –680 (2)
    Whereas existing methods of lossy/lossless floating-inductance simulation would require two to four operational amplifiers or current conveyors and compulsorily require exact matching of some components, this contribution presents a novel circuit which employs only a single current conveyor along with only three passive components to realise a floating-inductor (parallel RL), without any component-matching requirement.
    Add to favourites
    Export citations
Low-loss high-numerical-aperture optical fibre fabricated by v.a.d. method
Compensation of profile dispersion in graded-index optical fibres
  • Author(s): S. Geckeler
  • Source: Electronics Letters, Volume 15, Issue 21, p. 682 –683
  • DOI:  10.1049/el:19790484
  • Type: Article
  • + Show details - Hide details
  • p. 682 –683 (2)
    As the profile dispersion parameter P of graded-index fibres is wavelength-dependent. Marcatili's condition for achieving high bandwidth is usually satisfied only in a narrow wavelength range, if at all. This behaviour can be compensated by a wavelength-dependent refractive-index profile. This letter presents a profile function that compensates for a broad class of profile dispersions and may become a design criterion for fibres in the future, although its practical applicability is presently restricted by the limited variety of available glasses.
    Add to favourites
    Export citations
Fine tuning of s.a.w. resonators using argon ion bombardment
  • Author(s): S. James  and  I.H. Wilson
  • Source: Electronics Letters, Volume 15, Issue 21, p. 683 –684
  • DOI:  10.1049/el:19790485
  • Type: Article
  • + Show details - Hide details
  • p. 683 –684 (2)
    High-energy (40 to 240 keV) argon ion beams have been used for fine tuning of the stop/passband frequency (nominally 157 MHz) of Al/quartz Rayleigh wave transmission filters. An increase in frequency (accompanied by a reduction in impedance ratio) occurred for high ion energies and low ion doses, where the dominant effect appears to be amorphisation of the quartz surface with a reduction in mass loading due to swelling. The frequency shift was+120 kHz per 100 keV of bombarding ion energy for an ion dose of 1.5×1016 ions/cm2. A decrease in frequency occurred for low ion energies and high ion doses caused by the difference in sputtering rate between the quartz and the Al digits. The frequency shift in this case was −100 kHz for a dose of 1×1017 ions cm−2
    Add to favourites
    Export citations
Ray interpretation of the material signature in the acoustic microscope
Effect of chromatic dispersion on pulses of arbitrary coherence
Groove-guide connection losses at 100 GHz
Novel capacitor floatation scheme
Pumped Schottky diodes with noise temperatures of less than 100 K at 115 GHz
  • Author(s): Nigel J. Keen ; William M. Kelly ; Gerard T. Wrixon
  • Source: Electronics Letters, Volume 15, Issue 21, p. 689 –690
  • DOI:  10.1049/el:19790490
  • Type: Article
  • + Show details - Hide details
  • p. 689 –690 (2)
    New Schottky-barrier diodes, with an epitaxial layer thickness of < 1000 Å and doping 2.5×1016 cm−3, yield a mixer noise temperature of 98 K at 115 GHz. The diodes have a diameter of 1.8 μm, and show repeatable performance. Measurements indicate negligible capacitance variation to at least +0.2 V. The noise temperature is competitive with values reported for Josephson and quasiparticle junctions.
    Add to favourites
    Export citations
Minimisation of incompletely specified sequential machines: the ‘really’ excluded compatibility classes
  • Author(s): G. Palama  and  G.V. Russo
  • Source: Electronics Letters, Volume 15, Issue 21, p. 690 –691
  • DOI:  10.1049/el:19790491
  • Type: Article
  • + Show details - Hide details
  • p. 690 –691 (2)
    The known methods for the minimisation of incompletely specified sequential machines do not take into consideration the number of unspecified entries in the flow-table of the minimal machine. In this note, we show that the prime compatibility classes (following the definition of Grasselli and Luccio) do not allow such an additional condition. Here we give a more complete definition of the excluded compatibility classes and a method for deriving them.
    Add to favourites
    Export citations
System reduction by Routh approximation and modified Cauer continued fraction
Insensitive grounded-capacitor simulation of grounded inductors using current conveyors
Comparison of GaAs IMPATT designs for 20 GHz
Temperature dependence of InGaAsP double-heterostructure laser characteristics
Signal-processing operations on A-law companded speech
Alternative realisations of switched-capacitor floating inductors

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