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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 21, Issue 22, 24 October 1985

Volumes & issues:

Volume 21, Issue 22

24 October 1985

Phase-noise behaviour of frequency dividers implemented with GaAs heterojunction bipolar transistors
High-power operation of DCPBH lasers emitting at 1.52 μm wavelength
  • Author(s): D. Renner ; A.J. Collar ; P.D. Greene ; G.D. Henshall
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1006 –1007
  • DOI:  10.1049/el:19850713
  • Type: Article
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  • p. 1006 –1007 (2)
    Double-channel planar buried heterostructure (DCPBH) lasers emitting at 1.52 μm wavelength have been made with considerably reduced current leakage. These devices have reached a maximum CW output power of 50 mW per facet at 20°C and have operated CW up to 125°C. Both these figures are the highest values yet achieved for lasers emitting in the 1.52 μm wavelength region.
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Measurement of Rayleigh backscatter-induced linewidth reduction
Uniform bend loss of the TE0q mode in circular waveguides with small surface impedance and large surface admittance
Statistical characteristics of a laser diode exposed to Rayleigh backscatter from a single-mode fibre
Dependence of semiconductor laser linewidth on measurement time: evidence of predominance of 1/f noise
  • Author(s): K. Kikuchi  and  T. Okoshi
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1011 –1012
  • DOI:  10.1049/el:19850717
  • Type: Article
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  • p. 1011 –1012 (2)
    Linewidths of 1.3 μm InGaAsP lasers were measured by using delayed self-heterodyne set-ups with two different delay-line lengths, i.e. with two equivalent measurement times. It has been found that in high-power operation the linewidth increases as the measurement time becomes longer, and that this dependence is explained well by a calculation assuming that the 1/f noise in the FM noise spectrum is the predominant cause of the spectral broadening. The significance of this fact in coherent optical communications is discussed.
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Transfer characteristic of a linear phase detector for variable phase
Performance of a Fourier transform data transmission system
Microstrip termination effects on dielectric resonator filters
  • Author(s): R.J. Trew ; C.P. Hearn ; E.S. Bradshaw
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1015 –1017
  • DOI:  10.1049/el:19850720
  • Type: Article
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  • p. 1015 –1017 (3)
    The effect of microstrip termination on the noise figure and insertion loss performance of dielectric resonator filters has been investigated both theoretically and experimentally. Radiation loss from open- and short-circuited dielectric resonator coupling lines has been determined. It is shown that the use of short-circuited coupling lines results in significant improvements in the performance of the filter. The improvement increases as frequency increases.
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Practical frequency source for use in agile radars
Dispersion of linewidth-broadening factor in 1.5 μm laser diodes
High-silica single-mode optical reflection bending and intersecting waveguides
  • Author(s): A. Himeno ; M. Kobayashi ; H. Terui
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1020 –1021
  • DOI:  10.1049/el:19850723
  • Type: Article
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  • p. 1020 –1021 (2)
    Single-mode high-silica optical reflection bending and intersecting waveguides are examined under conditions of large bending and intersecting angles (5–90 degrees). The reflection bending waveguide shows a loss of 2 dB at the bending angle of less than 50 degrees. When the intersecting angle was 30 degrees or more, a small intersecting loss (less than 0.1 dB) and a low crosstalk (less than −20 dB) were attained.
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Alternative approach to Zakian's IMN approximant in numerical initial-value problems
Tunable circular patch antennas
  • Author(s): G.-L. Lan  and  D.L. Sengupta
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1022 –1023
  • DOI:  10.1049/el:19850725
  • Type: Article
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  • p. 1022 –1023 (2)
    A method to control the resonant or operating frequencies of circular patch antennas has been investigated experimentally and theoretically. It consists of the placement of passive metallic or tuning posts at approximate locations within the input region of the antenna. Comparison of measured and analytical results seems to establish the validity of a theoretical model proposed to determine the input performance of such circular patch antennas.
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3 km-long single-polarisation single-mode fibre
Very low threshold current ridge-waveguide AlGaAs/GaAs single-quantum-well lasers
Vectorial wave analysis of optical waveguides with rectangular cross-section using equivalent network approach
  • Author(s): M. Koshiba  and  M. Suzuki
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1026 –1028
  • DOI:  10.1049/el:19850728
  • Type: Article
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  • p. 1026 –1028 (3)
    The equivalent network approach is described for the analysis of optical waveguides with rectangular cross-section. A network representation is derived by taking the TE-TM coupling and the discrete-continuous spectrum coupling at the sides of the waveguide into account. The results of the vectorial wave analysis using this simple equivalent network agree well with those of the collocation method and of the finite-element method.
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HEMT 60 GHz amplifier
  • Author(s): J. Berenz ; K. Nakano ; Ting-Ih Hsu ; J. Goel
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1028 –1029
  • DOI:  10.1049/el:19850729
  • Type: Article
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  • p. 1028 –1029 (2)
    A high electron mobility transistor (HEMT) amplifier has been fabricated which exhibits 7.5 dB gain at 61 GHz. This result was obtained with a quarter-micrometre gate-length depletion-mode HEMT. Reduction of source-gate resistance and gate length are primarily responsible for this performance. The letter describes the materials and device processing technology developed for fabricating these devices.
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New approach to lossy optical waveguides
Bandpass adder channel for multiuser (collaborative) coding schemes
  • Author(s): A. Brine  and  P.G. Farrell
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1030 –1031
  • DOI:  10.1049/el:19850731
  • Type: Article
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  • p. 1030 –1031 (2)
    Many multiuser (collaborative) codes require a discrete multiple-access channel that provides the arithmetic addition of the users' transmitted symbol values. Problems arise with the transmission of bandpass symbols since the desired addition normally requires the users' carriers to be phasecoherent at the receiver. The letter proposes a simple modulation scheme which provides the required symbol addition with arbitrarily phased carriers.
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Measurement of intermodal delay in a dual-mode optical fibre
Biconical taper coaxial coupler filter
New wide-range fast-response analogue measurement of frequency
Switched-capacitor lossless discrete differentiator with modified sample-and-hold sequence
Monolithic integration of a 5.3 GHz regenerative frequency divider using a standard bipolar technology
  • Author(s): R.H. Derksen ; H.-M. Rein ; K. Wörner
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1037 –1039
  • DOI:  10.1049/el:19850736
  • Type: Article
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  • p. 1037 –1039 (3)
    A monolithic microwave frequency divider IC with an operating range of 1.4–5.3 GHz was developed and fabricated in a standard bipolar technology. The circuit operates on the principle of ‘regenerative frequency division’. Compared to the most popular divider concepts based on a master-slave D-flip-flop, an almost twice as high input frequency can be divided, provided that the same technology is used. A further advantage is the low power consumption.
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Switched-capacitor noise-shaping coders of higher order for A/D conversion
Extremely uniform threshold voltage distribution of GaAs FET made on LEC-grown crystals
  • Author(s): J. Kasahara ; M. Arai ; N. Watanabe
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1040 –1042
  • DOI:  10.1049/el:19850738
  • Type: Article
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  • p. 1040 –1042 (3)
    Extremely uniform threshold voltage distribution of a GaAs FET with a standard deviation of 7 mV in a 20 mm × 20 mm area of In-doped low-dislocation-density LEC-grown substrates was obtained after excluding several extraordinary data points. The deviation of the threshold voltage at the extraordinary data points was as large as 100–150 mV. No significant correlation of the extraordinary threshold voltage with distance of the gate to a nearest dislocation was observed.
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Bending loss measurement of LP11 mode in quasi-single-mode operation region
Offset-compensated bilinear SC filter of leapfrog type using a two-phase clock
Automated Hall effect profiler for electrical characterisation of semiconductors
Generation of a class of two-variable impedance functions from their real part using a state-variable technique
Measured dynamic linewidth properties of a 1.5 μm DFB-grin-rod coupled-cavity laser under direct high-frequency modulation
Extended-range parallel-path RC oscillator synthesis: a state-variable approach
  • Author(s): U.S. Ganguly
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1048 –1050
  • DOI:  10.1049/el:19850744
  • Type: Article
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  • p. 1048 –1050 (3)
    The letter points out the usefulness of state-variable techniques for realising the dynamics of a special class of RC oscillators which can be designed to oscillate at frequencies beyond the range constrained by the integrator time constants. By exploiting the ‘isotopic’ nature of state-variable structures, such extended-range oscillators can be synthesised which retain the canonic simplicity of four-element frequency-determining networks and which can also be tuned electronically with a single control.
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High-quality GaAs Schottky diodes fabricated by strained layer epitaxy
  • Author(s): P. Narozny  and  H. Beneking
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1050 –1051
  • DOI:  10.1049/el:19850745
  • Type: Article
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  • p. 1050 –1051 (2)
    High-quality GaAs Schottky diodes have been fabricated using a strained layer to improve the material quality. The epitaxial layer has been isoelectronically doped with In with a concentration of 4×1019 cm−3. The diodes fabricated on these layers show a reverse current of 100 pA–200 pA up to 50 V reverse-bias voltage at room temperature. The Schottky contact area was 7500 μm2 and the doping concentration 1×1016 cm−3. An excellent, reproducible ideality factor of 1.02 has been obtained over seven decades of forward current. Results of Schottky diodes fabricated on isoelectronically doped layers in comparison to conventionally fabricated devices are reported.
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Defect-tolerant active matrix circuit with duplicated data input routes for large liquid crystal display
Correlation measurements in precipitation at linear polarisation using dual-channel radar
  • Author(s): Y.M.M. Antar  and  A. Hendry
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1052 –1054
  • DOI:  10.1049/el:19850747
  • Type: Article
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  • p. 1052 –1054 (3)
    Correlation measurements at linear polarisation in dual-channel precipitation radars are investigated. It is shown that the correlation between orthogonal linearly polarised back-scatter components provides information on precipitation particle orientation and shape. Thus, as is the case at circular polarisation, correlation measurements can be a useful concept for particle identification. Preliminary results from measurements made at 9.6 GHz are presented.
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Path loss characteristics of 60 GHz transmissions
Novel higher-order active filter design using current conveyors
  • Author(s): R. Senani
  • Source: Electronics Letters, Volume 21, Issue 22, p. 1055 –1057
  • DOI:  10.1049/el:19850749
  • Type: Article
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  • p. 1055 –1057 (3)
    A novel method of designing higher-order filters using current conveyors (CCs) is presented in which a new type of impedance scaling of LC ladder prototypes facilitates direct incorporation of a class of nonideal simulated inductors and FDNRs in active filter design. The resulting structures are minimum-sensitive and require a very small number of CCs (typically, equal to the number of reactive elements in the passive prototype). Experimental results have confirmed the practical validity of the ideas.
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14 GHz band GaAs monolithic analogue frequency divider
Erratum: Optimisation of dimensions of single V-groove guide

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