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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 25, Issue 12, 8 June 1989

Volumes & issues:

Volume 25, Issue 12

8 June 1989

Optical FSK transmission with pattern-independent 119 photoelectrons/bit receiver sensitivity and endless polarisation control
Dependence of photoluminescence peak energy of MOVPE-grown AlGaInP on substrate orientation
All current-mode frequency selective circuits
  • Author(s): G.W. Roberts  and  A.S. Sedra
  • Source: Electronics Letters, Volume 25, Issue 12, p. 759 –761
  • DOI:  10.1049/el:19890513
  • Type: Article
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  • p. 759 –761 (3)
    This letter proposes an entirely new method for performing analogue signal filtering. All circuits are based upon current amplifiers but derived from well-known voltage amplifier circuits. These circuits possess the same sensitivity properties as their voltage amplifier counterparts. However, it is expected that these circuits will operate at higher signal bandwidths, with greater linearity, and have larger dynamic range than their voltage-based circuit counterparts.
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Remarkable reduction of threshold current density of 670 nm GaInAsP/AlGaAs visible lasers by increasing al content of AlGaAs cladding layers
Constant-input stability of some known digital biquads
On arrival of paths in fading multipath indoor radio channels
10 MHz CMOS OTA-C voltage-controlled quadrature oscillator
  • Author(s): B. Linares-Barranco ; A. Rodríguez-Vázquez ; E. Sánchez-Sinencio ; J.L. Huertas
  • Source: Electronics Letters, Volume 25, Issue 12, p. 765 –767
  • DOI:  10.1049/el:19890517
  • Type: Article
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  • p. 765 –767 (3)
    A quadrature-type voltage-controlled oscillator with operational transconductance amplifiers and capacitors (OTA-C is presented. A monolithic integrated CMOS test circuit is introduced to verify theoretical results. The attainable frequency range of oscillation of the chip test circuit is 3–10.34 MHz. The total harmonic distortion (THD) is 020– 1.87% for corresponding peak-to-peak amplitude voltages between 100 mV and 1 V. This amplitude can be controlled either by using a diode connection of two MOS transistors or a proposed nonlinear resistor.
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Compression and dispersionless transmission of chirped 1.3 μm DFB ps laser pulses in dispersion-shifted single-mode fibres
Low-threshold 1.5μm DFB laser grown by GSMBE
  • Author(s): B. Fernier ; C. Artigue ; D. Bonnevie ; L. Goldstein ; A. Perales ; J. Benoit
  • Source: Electronics Letters, Volume 25, Issue 12, p. 768 –770
  • DOI:  10.1049/el:19890519
  • Type: Article
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  • p. 768 –770 (3)
    GaInAsP 1.5μm DFB lasers with a low threshold current (17 mA) have been grown by gas source molecular beam epitaxy (GSMBE) in a two-step epitaxial process. The lasers exhibit single-mode emission for emitted power in excess of 10 mW with side mode suppression ratio of 40 dB and spectral linewidth of 15 MHz. In addition the dispersion of the lasing wavelength has been found to be as low as 1.7 nm.
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AlGaAs/GaAs multiquantum-well (MQW) surface-emitting laser
Effective optical transit time in direct electro-optic sampling of GaAs coplanar integrated circuits
  • Author(s): T. Shibata ; T. Nagatsuma ; E. Sano
  • Source: Electronics Letters, Volume 25, Issue 12, p. 771 –773
  • DOI:  10.1049/el:19890521
  • Type: Article
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  • p. 771 –773 (3)
    The effective optical transit time τEOTT in direct electro-optic sampling of various coplanar lines is calculated on theassumption of TEM-mode signal propagation. It is shownthat τEOTT strongly depends on the sampling position. τEOTT of 1–2 ps at the best sampling point are calculated for the reflection-mode probing of lines in MMlCs, which is considered to be the ultimate limit of measurement time resolution.
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Blocking method for RSA cryptosystem without expanding cipher length
  • Author(s): M. Shimada  and  K. Tanaka
  • Source: Electronics Letters, Volume 25, Issue 12, p. 773 –774
  • DOI:  10.1049/el:19890522
  • Type: Article
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  • p. 773 –774 (2)
    A blocking method for the RSA cryptosystem is presented. It causes no expansion in block size by encipherment. The heart of the proposed method is the encryption function which involves two RSA encryptions interleaved with a domain interchanging function. This method enables easy adoption of the RSA cryptosystem to already established systems. Moreover, this method is a simple solution to the reblocking problem.
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Interferometric measurement of low-frequency phase noise characteristics of diode laser-pumped Nd:YAG ring laser
  • Author(s): K.J. Williams ; A. Dandridge ; A.D. Kersey ; J.F. Weller ; A.M. Yurek ; A.B. Tveten
  • Source: Electronics Letters, Volume 25, Issue 12, p. 774 –776
  • DOI:  10.1049/el:19890523
  • Type: Article
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  • p. 774 –776 (3)
    We report the interferometric measurement of the phase noise characteristics of a diode laser-pumped solid-state Nd:YAG 1.3μ laser based on a nonplanar ring cavity. Results show that the device has a low-frequency phase noise approximately three orders of magnitude lower than that observed with semiconductor diode lasers. The use of this source in fibre sensing applications is discussed.
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Fundamental limit on number of channels in subcarrier-multiplexed lightwave CATV system
Cryogenic temperature performance of modulation-doped field-effect transistors
  • Author(s): J. Kolodzey ; J. Laskar ; S. Boor ; S. Reis ; A. Ketterson ; I. Adesida ; D. Sivco ; R. Fischer ; A.Y. Cho
  • Source: Electronics Letters, Volume 25, Issue 12, p. 777 –779
  • DOI:  10.1049/el:19890525
  • Type: Article
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  • p. 777 –779 (3)
    We report S-parameter measurements of AlInAs/GalnAs/ InP modulation-doped field-effect transistors (MODFETs) at cryogenic temperatures. The current gain at 80 K is 3dB higher than at 300 K, and the current gain cutoff frequency fT increases from 32 GHz at 300 K, to 42 GHz at 80 K, which is the first observation of higher fT by direct measurement.
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Tree array lasers
Index mapping for one to multi dimensions
10 Gbit/s monolithic integrated bipolar demultiplexer for optical-fibre transmission systems fabricated in BICMOS technology
Selectively silicided vertical power DMOSFETs for high-frequency power conversion
  • Author(s): K. Shenai ; P.A. Piacente ; R. Saia ; C.S. Korman ; B.J. Baliga
  • Source: Electronics Letters, Volume 25, Issue 12, p. 784 –785
  • DOI:  10.1049/el:19890529
  • Type: Article
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  • p. 784 –785 (2)
    A 50 V, 056mΩcm2 vertical power DMOSFET fabricated using selectively silicided gate and source contact regions is reported. The gate-source isolation was provided by anisotropically etched oxide sidewall spacers. This new device structure lowers the source contact resistance considerably by providing a larger contact area and improves the distributed gate RC propagation delay by lowering the gate sheet resistance compared with the conventional heavily doped n+-polysilicon gates. Devices with cell density as high as 8 million cells/inch2 and die size as large as 200 mil × 220 mil and capable of conducting more than 160 A of current have been successfully fabricated with excellent gate yield. These results represent the highest reported forward conductivities for any type of power FET in the 50 V reverse blocking range
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Minimum norm reconstruction of band-limited function from regularly or irregularly spaced samples
New scheme for vector quantisation of speech signals
Spectral domain analysis of coplanar superconducting line laid on multilayered GaAs substrate
  • Author(s): D. Kinowski ; F. Huret ; P. Pribetich ; P. Kennis
  • Source: Electronics Letters, Volume 25, Issue 12, p. 788 –789
  • DOI:  10.1049/el:19890532
  • Type: Article
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  • p. 788 –789 (2)
    In this letter we show the influence of superconducting strips on the propagation characteristics of a MIS or a Schottky contact coplanar line laid on a GaAs substrate. The use of superconducting strips instead of metallic strips makes it possible to decrease losses. However the main purpose of our study is to point out the influence of the superconductor on the slowing factor and on the characteristic impedance.
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Gain ripple minimisation and higher-order modes in semiconductor optical amplifiers
Synthesis of uncorrelated and nonsquare sets of multilevel complementary sequences
Phase tracking Viterbi demodulator
Coding moving image sequences by segmentation of difference frames and motion-adaptive frame interpolation
  • Author(s): M. Soryani  and  R.J. Clarke
  • Source: Electronics Letters, Volume 25, Issue 12, p. 794 –795
  • DOI:  10.1049/el:19890536
  • Type: Article
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  • p. 794 –795 (2)
    Motion-compensated difference frames derived from a moving image sequence are adaptively segmented into regions of constant intensities. Region boundaries are then coded and transmitted together with region intensities. Only alternate frames are coded and transmitted, skipped frames being reproduced at the receiver by motion-adaptive interpolation. The resulting quality of the reconstructed sequence is markedly superior to that obtained when segmentation is applied to the image frames themselves.
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New approach to fuzzy learning in dynamic systems
Intermodal coupler using permanently photoinduced grating in two-mode optical fibre
Cyclic three-phase amplitude jitter in mode-locked semiconductor lasers
Permittivity of dielectric-conductor mixture: application of logarithmic law of mixing to electric susceptibility
Reduction of emitter thickness in AlGaAs/GaAs heterojunction bipolar transistor
  • Author(s): S. Tadayon ; B. Tadayon ; P.J. Tasker ; W.J. Schaff ; L.F. Eastman
  • Source: Electronics Letters, Volume 25, Issue 12, p. 802 –803
  • DOI:  10.1049/el:19890541
  • Type: Article
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  • p. 802 –803 (2)
    The effects of AlGaAs layer thickness and GaAs cap layer thickness in the emitter of abrupt npn AlGaAs/GaAs heterojunction bipolar transistors on the performance of devices were investigated experimentally. It was found that only 500 Å of A10.25Ga0.75As layer in the emitter is enough to produce high injection efficiency and a small signal current gain of more than 1100
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Novel square-law demodulator for use in coherent ASK/FSK heterodyne optical receivers
EEPROM synapses exhibiting pseudo-Hebbian plasticity
  • Author(s): H.C. Card  and  W.R. Moore
  • Source: Electronics Letters, Volume 25, Issue 12, p. 805 –806
  • DOI:  10.1049/el:19890543
  • Type: Article
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  • p. 805 –806 (2)
    Dynamic analogue learning in VLSI neural networks can be achieved with low synaptic complexity using EEPROM devices of the floating gate tunnel oxide type. When logarithmic neural voltages are employed, learning algorithms describing synaptic plasticity that approximate multiplicative Hebbian learning rules can be implemented. This does not require the high transistor count of conventional analogue multiplier circuits.
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