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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 17, Issue 19, 17 September 1981

Volumes & issues:

Volume 17, Issue 19

17 September 1981

Noise characteristics in line-narrowed semiconductor lasers with optical feedback
  • Author(s): L. Goldberg ; A. Dandridge ; R.O. Miles ; T.G. Giallorenzi ; J.F. Weller
  • Source: Electronics Letters, Volume 17, Issue 19, p. 677 –678
  • DOI:  10.1049/el:19810473
  • Type: Article
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  • p. 677 –678 (2)
    Effects of optical-feedback-induced line-narrowing on low-frequency amplitude and phase noise of semiconductor lasers are reported. Free-running laser noise is compared with that of lasers operating with external mirror feedback. While less than 1 dB difference in the amplitude noise with and without feedback is observed, line-narrowed lasers exhibit 15–20 dB reduction in low-frequency wavelength instability, or phase noise.
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Characteristics of phase-matched sum-frequency light in optical fibres
Cochannel interference immunity of high capacity QAM
Simple design of x-junction microstrip circulators
  • Author(s): A.-M. Khilla
  • Source: Electronics Letters, Volume 17, Issue 19, p. 681 –682
  • DOI:  10.1049/el:19810476
  • Type: Article
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  • p. 681 –682 (2)
    The modes used in the construction of x-junction microstrip circulators are a pair of radial TM±3,1,0 degenerate modes and a radial TM0,1,0 mode. A direct magnetic field is applied to split the degeneracy between the former modes. A micro-strip ring resonator is chosen to immediately satisfy the first two of the three circulation conditions for this type of junction. Experimental results support theoretical designs.
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Effect of threshold offsets in zero-crossing speech detector
Original improvements of TLM method
  • Author(s): M. Leroy
  • Source: Electronics Letters, Volume 17, Issue 19, p. 684 –685
  • DOI:  10.1049/el:19810478
  • Type: Article
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  • p. 684 –685 (2)
    The use of the three-dimensional-TLM method is limited, first, by an excessive computation time and, secondly, by the variability of the results when the position of the point of observation varies. An original approach is described which improves the first point and avoids the second one. The resonant frequencies of the studied cavity are computed by applying Prony's method to time variations of the electric energy located inside the cavity. Numerical results are given in the case of the ridged waveguide cavity.
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Deep hole traps in VPE p-type InP
Electron concentration and alloy composition dependence of Hall factor in GaxIn1−xAsyP1−y
  • Author(s): Y. Takeda ; M.A. Littlejohn ; J.A. Hutchby ; R.J. Trew
  • Source: Electronics Letters, Volume 17, Issue 19, p. 686 –688
  • DOI:  10.1049/el:19810480
  • Type: Article
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  • p. 686 –688 (3)
    The Hall factor is calculated by the iterative method over whole composition range of GaxIn1−xAsyP1−y lattice-matched to InP. The electron concentrations used are 1×1016 cm−3 and 1×1017 cm−3, with carrier compensation ratios (ND+NA/n 1, 2, and 5, which are commonly observed in grown GaInAsP alloys. The Hall factor decreases with increasing alloy content y for relatively low electron concentrations, but this is not the case in compensated alloys because of varying predominance of scattering mechanisms with composition and ionised impurity concentration.
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Symmetrical Mott barrier as a fast photodetector
  • Author(s): C.J. Wei ; H.-J. Klein ; H. Beneking
  • Source: Electronics Letters, Volume 17, Issue 19, p. 688 –690
  • DOI:  10.1049/el:19810481
  • Type: Article
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  • p. 688 –690 (3)
    A novel surface-oriented GaAs punch-through photodetector possessing a fast photoresponse and a moderate internal gain is described. The device has a simple planar MnM structure consisting of two Schottky contacts which thereby facilitate the fabrication. The detector exhibits an internal rise time as fast as 20 ps with a full width at half maximum (FWHM) of 35 ps. The internal gain of the detector was estimated to be 3. The noise equivalent power was measured to be 4×10−11 W/√Hz. The detector represents one of the fastest GaAs photodetectors reported to date.
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Dielectric measurements in the X-band of mamma tissue from cattle
Phase-lock-loop operating ranges measurement
  • Author(s): R.C. Den dulk  and  M.P.I. Huisman
  • Source: Electronics Letters, Volume 17, Issue 19, p. 691 –693
  • DOI:  10.1049/el:19810483
  • Type: Article
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  • p. 691 –693 (3)
    A measurement method is presented that quickly displays the operating ranges of phase-lock loops (PLLs) and acquisition aids under various input conditions such as noise and interference. The PLL measurement set-up is based on the use of normally available spectrum analyser/tracking generator equipment rather than on the common display of the control voltage of the oscillator. It is shown that in case of a narrow-band PLL the spectrum-analyser display can be more easily interpreted than the control-voltage display.
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Novel CMOS Schmitt trigger
  • Author(s): K. Nagaraj  and  M. Satyam
  • Source: Electronics Letters, Volume 17, Issue 19, p. 693 –694
  • DOI:  10.1049/el:19810484
  • Type: Article
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  • p. 693 –694 (2)
    A novel CMOS Schmitt trigger using only four MOS transistors is discussed. This circuit, which works on the principle of load-coupled regenerative feedback, can be implemented using conventional CMOS technology with only one extra fabrication step. It can be implemented even more easily in CMOS/SOS (silicon-on-sapphire) integrated circuits. The hysteresis of this Schmitt trigger can be controlled by a proper choice of the transistor geometries.
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Fusion mass-splicing for optical fibres by discharge heating
Schmitt trigger circuit with picosecond risetimes
Wide-sense nonblocking network made of square switches
Improved mobility in OM-VPE-grown Ga1−xInxAs
  • Author(s): W.T. Dietze ; M.J. Ludowise ; C.B. Cooper
  • Source: Electronics Letters, Volume 17, Issue 19, p. 698 –699
  • DOI:  10.1049/el:19810488
  • Type: Article
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  • p. 698 –699 (2)
    The use of a tirmethylindium-trimethylarsenic adduct, which is synthesised in the gas phase, as the In source, and AsH3 as the primary As source is reported for the growth of high-quality Ga1−xInxAs (x<0.20). The improved epitaxial layers have higher mobilities and lower background doping than those grown with trimethylarsenic as the sole As source. The effects of elevated growth temperatures are also reported.
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Radar echoes near a dielectric resonance
Fast calculation of impulse responses without multiplications
E-type circulator for fin lines
PIN diodes in meander-line filters for multiplexing applications
In0.53Ga0.47As contact layer for 1.3 μm light-emitting diodes
  • Author(s): H. Temkin ; A.K. Chin ; M.A. Digiuseppe
  • Source: Electronics Letters, Volume 17, Issue 19, p. 703 –705
  • DOI:  10.1049/el:19810493
  • Type: Article
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  • p. 703 –705 (3)
    Measurements of the specific contact resistance on epitaxially grown layers of p-In1−xGaxAsyP1−y as a function of composition demonstrate the resistance minimum of 7×10−6 Ωcm2 for In0.53Ga0.47As. Growth procedures for the preparation of InGaAsP/InP double-heterostructure LED wafers incorporating such a ternary InGaAs contact layer are described. This contacting technique allows fabrication of high-performance devices with reproducibly low series resistance.
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Pseudoactive bridge for separation of R and C in a practical capacitive/conductive transducer
  • Author(s): K. Padmanabhan  and  G.S. Somayajulu Sarma
  • Source: Electronics Letters, Volume 17, Issue 19, p. 705 –706
  • DOI:  10.1049/el:19810494
  • Type: Article
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  • p. 705 –706 (2)
    An effective and unique method of measuring independently the variations of resistive and capacitive constituents of a practical capacitive transducer using an improved pseudo-active bridge is described. The impedance change in some types of transducers may be due to changes in resistance and/or capacitance either way. Separation of changes in resistance and capacitance results in a better understanding of the transduced variable. The active bridge which separates the changes is suitable for online determination of the two changes.
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Method of fabricating high-Q silicon varactor diodes
  • Author(s): A. Rosen ; C.P. Wu ; M. Caulton ; A. Gombar ; P. Stabile
  • Source: Electronics Letters, Volume 17, Issue 19, p. 707 –708
  • DOI:  10.1049/el:19810495
  • Type: Article
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  • p. 707 –708 (2)
    A new processing technique has been developed for the fabrication of high-Q and high-voltage varactor diodes. The process utilises ion implantation and laser annealing for heavily-doped p++ and n++ layers and epitaxial growth for low impurity concentrations. The technique provides good yield and repeatability, and it has allowed fabrication of varactor diodes which have breakdown voltages of 120 V and a Q as high as 600 at −8 V bias and 50 MHz frequency.
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InP Gunn oscillators in V-band
Method for direct multiway branching in microprogram control
Comment: Algorithm for sampled data signal flow graphs
Spectral calculation of partial response multi-h phase codes
Dielectric properties of blood plasma
Low-threshold stripe geometry lasers by metalorganic chemical vapour deposition (MO-CVD)
Modulation characteristic and intensity noise of CW superluminescent diodes
Stability test for multidimensional digital filters
Reflection analysis of flanged circular waveguide radiating through small aperture into absorbing medium
  • Author(s): C. Fray ; K. Chandrasekhar ; A. Papiernik
  • Source: Electronics Letters, Volume 17, Issue 19, p. 718 –720
  • DOI:  10.1049/el:19810504
  • Type: Article
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  • p. 718 –720 (3)
    A flanged circular waveguide in dominant-mode operation, radiating through a small circular aperture into an absorbing medium, has been studied from the point of view of reflections caused in the guide. The effect of varying the aperture size in modifying the reflections in amplitude and phase has been determined; the proper choice needed to realise matched conditions have been determined for a few selected media.
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Spectral distribution of a sampled 1st-order lowpass filtered white noise
Comment: Voltage transfer function shift theorem
Erratum: Low-distortion high-output class B current convertor using error feedforward
Erratum: Time-dependent thermal effects in current-modulated semiconductor lasers

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