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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 22, Issue 12, 5 June 1986

Volumes & issues:

Volume 22, Issue 12

5 June 1986

Compensation of line-broadening factor in twin-stripe semiconductor lasers and improved modulation potential
Electro-optic tunable filter
New analysis of microbending losses in single-mode fibres
Generation currents, noise and auger suppression in intrinsic diodes
Hybrid modes in a dielectric lined conical waveguide
Optimisation of spacer layer thickness in n-AlxGa1−xAs/p+-GaAs heterojunction diodes grown by molecular beam epitaxy
  • Author(s): B. Khamsehpour ; K.E. Singer ; J.A. Van Den Berg ; J.C. Vickerman
  • Source: Electronics Letters, Volume 22, Issue 12, p. 627 –629
  • DOI:  10.1049/el:19860430
  • Type: Article
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  • p. 627 –629 (3)
    The effect of an undoped GaAs spacer layer at the heterojunction interface of MBE-grown n-AlxGa1−xAs/p+-GaAs diodes has been investigated by electroluminescence, dynamic secondary ion mass spectrometry and current/voltage measurements. A consistent picture emerges of the role of the spacer layer in accommodating beryllium migration. A simple procedure to optimise the spacer layer thickness is suggested.
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60 GHz BARITT diodes as self-oscillating mixers
Limits of FET modelling by lumped elements
Effect of Au:Ge thickness on ohmic contacts to GaAs
Millimetre-waveguide-mounted InGaAs photodetectors
Sine-wave generation using a high-order lowpass switched-capacitor filter
Low dark current GaAs/AlAs graded-parameter superlattice PIN photodetector
  • Author(s): N.R. Couch ; D.G. Parker ; M.J. Kelly ; T.M. Kerr
  • Source: Electronics Letters, Volume 22, Issue 12, p. 636 –637
  • DOI:  10.1049/el:19860436
  • Type: Article
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  • p. 636 –637 (2)
    Preliminary measurements of the photoresponse of a GaAs p-n junction containing an undoped asymmetric GaAs/AlAs superlattice are presented. Very low reverse-bias dark currents (<6×10−8 A/cm2 at 3 V) are measured, while still retaining the speed and spectral response of a conventional GaAs PIN diode. The −3 dB bandwidth is found to be greater than 1 GHz, and the responsivity is 0.1 A/W.
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Reflection high-energy electron diffraction from lithium niobate single-crystal surfaces for application in molecular beam epitaxy
  • Author(s): M. Petrucci  and  C.W. Pitt
  • Source: Electronics Letters, Volume 22, Issue 12, p. 637 –639
  • DOI:  10.1049/el:19860437
  • Type: Article
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  • p. 637 –639 (3)
    A modified RHEED system has been constructed to study nonconductive crystal lithium niobate (LiNbO3) using electron energies up to 50 keV. The problems encountered are discussed and preliminary results presented. We outline the potential use of the technique in the routine analysis of insulating substrates prior to the deposition of epitaxial layers by MBE, and in the examination of the deposited layers.
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Geometric birefringence in fibres due to asymmetric cladding
New sequences for asynchronous frequency-hopping multiplex
Self-adjusted permanent attachment of fibres to GaAs waveguide components
Analysis of symmetric Y-junction laser arrays with uniform near-field distribution
  • Author(s): Kuo-Liang Chen  and  Shyh Wang
  • Source: Electronics Letters, Volume 22, Issue 12, p. 644 –645
  • DOI:  10.1049/el:19860441
  • Type: Article
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  • p. 644 –645 (2)
    The analysis of a Y-junction laser array is presented. It is shown that the lowest-order cavity mode of this array has the lowest threshold gain and is thus preferentially excited. This mode has a uniform near-field distribution. Compared with the sinusoidal near-field distribution of the supermodes of the evanescently coupled laser arrays, this uniformity not only can delay the onset of the spatial-hole burning, which is the source of unstable far-field characteristic at high power level, it also allows for higher total power output before catastrophic mirror damage.
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Optical and electronic reduction of Rayleigh backscatter noise in fibre-coupled semiconductor diode lasers
60 GHz low-noise high-electron-mobility transistors
  • Author(s): K.H.G. Duh ; P.C. Chao ; P.M. Smith ; L.F. Lester ; B.R. Lee
  • Source: Electronics Letters, Volume 22, Issue 12, p. 647 –649
  • DOI:  10.1049/el:19860443
  • Type: Article
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  • p. 647 –649 (3)
    The noise performance of 0.25 μm-gate-length high-electron-mobility transistors at frequencies up to 62 GHz is reported. A room-temperature extrinsic transconductance gm of 480 mS/mm and a maximum frequency of oscillation fmax of 135 GHz are obtained for these transistors. At 30 and 40 GHz the devices exhibit minimum noise figures of 1.5 and 1.8 dB with associated gains of 10.0 and 7.5 dB, respectively. A minimum noise figure as low as 2.7 dB with an associated gain of 3.8 dB has also been measured at 62 GHz. This is the best noise performance ever reported for HEMTs at millimetre-wave frequencies. The results clearly demonstrate the potential of short-gate-length high-electron-mobility transistors for very low-noise applications for frequencies at least up to V-band.
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Improving the optimum generalised stop-and-wait ARQ scheme
Measurement of real-time digital signals in a silicon bipolar junction transistor using a noninvasive optical probe
Monolithic integration of InGaAs/InP PIN PD with MISFET on stepless substrate
High-performance SAW dispersive delay line using reflective thin metal dot arrays
  • Author(s): F. Huang ; E.G.S. Paige ; D.R. Selviah
  • Source: Electronics Letters, Volume 22, Issue 12, p. 653 –654
  • DOI:  10.1049/el:19860447
  • Type: Article
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  • p. 653 –654 (2)
    The first U-path surface-acoustic-wave (SAW) reflective array compressor (RAC) employing reflective arrays of thin metal dots on lithium niobate is reported. The thin rectangular metal dots are made together with the transducers in a single photolithographic step. Performance comparable with that of large time-bandwidth, conventional, grooved RACs is demonstrated, in good agreement with the design.
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Iterative integral equation solution for cylindrical dielectric resonator
Rain attenuation successive fade durations and time intervals between fades in a satellite-Earth link
  • Author(s): E. Matricciani  and  M. Mauri
  • Source: Electronics Letters, Volume 22, Issue 12, p. 656 –658
  • DOI:  10.1049/el:19860449
  • Type: Article
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  • p. 656 –658 (3)
    Long-term attenuation data at 11.6 GHz, obtained in a Sirio link, are analysed to provide information on the joint statistics between successive fade durations within a rain event (intrafade) and between different rain events (interfade). The results show that successive fade durations and the interfade or intrafade intervals are approximately statistically independent. Within the same rain event, interfades and fade durations longer than 10 s are statistically identical. These data may be important for planning adaptive systems and for devising prediction models of the dynamic behaviour of rain attenuation.
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Pseudocoherent FSK demodulation
  • Author(s): A.V. Shah ; K.H.S. Rao ; A. Kapetanovic
  • Source: Electronics Letters, Volume 22, Issue 12, p. 658 –659
  • DOI:  10.1049/el:19860450
  • Type: Article
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  • p. 658 –659 (2)
    A novel scheme of a ‘pseudocoherent’ FSK demodulator is proposed. Computer simulation and hardware-measured test results are given. It is shown that this new scheme gives lower bit error rates than the noncoherent demodulator, but has a comparable circuit complexity. Furthermore, its filtering requirements are minimal; this fact makes it especially suitable for a low-cost integrated FSK modem.
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Monolithic superconductor-base hot-electron transistors with large current gain
Pipelined carry look-ahead adder
  • Author(s): D.G. Crawley  and  G.A.J. Amaratunga
  • Source: Electronics Letters, Volume 22, Issue 12, p. 661 –662
  • DOI:  10.1049/el:19860452
  • Type: Article
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  • p. 661 –662 (2)
    A pipelined carry look-ahead adder is described which is particularly suitable for use with a pipelined parallel multiplier, but would also be useful for other pipelined systems. The adder is compared with a pipelined ripple-carry adder having a triangular structure and the nonpipelined form of the carry look-ahead adder and is shown to possess the advantages of small stage delay and short flush time.
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Universal active filter using current conveyors
Adaptive echo canceller employing DM encoding
  • Author(s): C.C. Evci
  • Source: Electronics Letters, Volume 22, Issue 12, p. 664 –665
  • DOI:  10.1049/el:19860454
  • Type: Article
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  • p. 664 –665 (2)
    The letter presents an echo canceller employing both delta modulation (DM) and a least-mean-square (LMS) adaptive filter. An adaptive filter operating on a DM binary output sequence attempts to model the echo path. This tandem connection can significantly reduce the hardware complexity. The proposed scheme appears to have considerable potential in telecommunications as the results are comparable to those obtained from the classical echo canceller with PCM.
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Zero-insertion-loss random-access fibre-optic data ring based on the Faraday effect
New CMOS floating voltage-controlled resistor
  • Author(s): K. Nagaraj
  • Source: Electronics Letters, Volume 22, Issue 12, p. 667 –668
  • DOI:  10.1049/el:19860456
  • Type: Article
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  • p. 667 –668 (2)
    A new CMOS floating voltage-controlled resistor for continuous-time filtering applications is described. The value of the resistance simulated by this circuit is independent of the threshold voltage of the transistors. This allows us to obtain a larger input range and also minimises the effects of threshold voltage mismatches and substrate noise. These improvements are obtained at the expense of a higher sensitivity to mismatches in the W/L ratios of the transistors.
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New AC thin-film electroluminescent device with frequency-controlled brightness characteristics
Tunable 8-channel wavelength demultiplexer using an acousto-optic light deflector
Influence of nonlinear dispersion in coherent narrowband amplification by stimulated Brillouin scattering
High-speed ring oscillators using planar p+-gate n-AlGaAs/GaAs 2DEG FETs
  • Author(s): Y. Suzuki ; H. Hida ; H. Toyoshima ; K. Ohata
  • Source: Electronics Letters, Volume 22, Issue 12, p. 672 –674
  • DOI:  10.1049/el:19860460
  • Type: Article
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  • p. 672 –674 (3)
    An E/R DCFL ring oscillator has been fabricated using a planar n-AlGaAs/GaAs 2DEG enhancement FET with p+-gate structure. For 1 μm gate length E-FETs, the standard deviation of threshold voltage was as small as 17.6 mV at 0.016 V average threshold voltage. At room temperature, a gate propagation delay of 15 ps/gate at a 5.25 mW/gate power dissipation was obtained from a 25-stage ring oscillator. A small minimum power-delay product of 14 fJ/gate was attained at 0.65 V supply voltage.
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Testing lithium niobate boules for integrated optics applications
Crosstalk due to three-wave mixing process in a coherent single-mode transmission line
Gigahertz voltage-controlled ring oscillator
Mode selectivity in DFB lasers with a second-order grating
Demonstration of a narrowband Bragg-reflection filter in a single-mode fibre directional coupler
Erratum: Avalanche GaAlAs/GaAs heterojunction phototransistor with optoelectronic bistability
Erratum: Improved sequential linear prediction by selective time-domain coefficient extraction

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