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image of Volume 22, Issue 23
Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 22, Issue 23, 6 November 1986

Volumes & issues:

Volume 22, Issue 23

6 November 1986

Improved algorithm based on pole enhancement for estimation of the vocal tract frequency response
Planar surface buried-heterostructure InGaAsP/InP lasers with hydride VPE-grown Fe-doped highly resistive current-blocking layers
  • Author(s): S. Sugou ; Y. Kato ; H. Nishimoto ; K. Kasahara
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1214 –1215
  • DOI:  10.1049/el:19860832
  • Type: Article
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  • p. 1214 –1215 (2)
    The fabrication and lasing characteristics for planar surface buried-heterostructure InGaAsP/InP lasers with highly resistive current-blocking layers are reported. Embedding growth was successfully performed by Fe-doping hydride VPE. Single transverse mode operation has been realised in lasers with a narrow active region, without any nonradiative recombination increase, due to an Fe-associated deep level. High-frequency response up to 10GHz was also demonstrated.
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Application of electro-optic frequency shifters in heterodyne interferometric systems
MOVPE growth and characteristics of Fe-doped semi-insulating InP layers
TDMA fibre-optic network with optical processing
Taylor series approach to functional approximation for inversion of Laplace transforms
  • Author(s): Huang-Yuan Chung  and  York-Yih Sun
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1219 –1221
  • DOI:  10.1049/el:19860836
  • Type: Article
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  • p. 1219 –1221 (3)
    The letter is devoted to a functional approximation for inversion of the Laplace transform. The function is approximated by a truncated Taylor series, which is expanded about t0=0. Utilising a special transformation, each Laplace transform is converted into a set of simultaneous linear algebraic equations which are then easily computed to give the coefficients of the basis function. Two examples with satisfactory results are given.
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Analysis of fused couplers by the effective-index method
Control of section-asymmetry crosstalk in Δβ-reversal directional coupler switches
Injection-locking of a wide-stripe AlGaAs/GaAs GRIN-SCH SQW laser
Design of minimum-phase FIR digital filter through cepstrum
  • Author(s): G.R. Reddy
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1225 –1227
  • DOI:  10.1049/el:19860840
  • Type: Article
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  • p. 1225 –1227 (3)
    A method to design an equiripple minimum-phase FIR filter using the cepstrum is described. This method avoids the complicated polynomial root-finding algorithm of Herrman and Schuessler (1970), or the phase-unwrapping algorithm associated with the complex cepstrum of Mian and Nainar (1982). The differential cepstrum method proposed by Pei and Lu (1986) has aliasing problems and requires the computation of three FFTs. The proposed method requires only two FFT computations and avoids the processing of phase.
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Polarisation characteristics of fused-fibre coupler as quarter-wave device in 1.55μm-wavelength region
Flip-flop circuit using a resonant-tunnelling hot electron transistor (RHET)
Optical third-harmonic generation from Langmuir-Blodgett merocyanine dye thin films
Spectral linewidth of an AlGaAs/GaAs DFB-TJS external-cavity laser with optical phase control loop
Temperature dependence of resonant frequency in optically excited diaphragms
Early effect of high-current-gain heterojunction bipolar transistor
  • Author(s): H. Wang  and  J. Dangla
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1234 –1236
  • DOI:  10.1049/el:19860846
  • Type: Article
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  • p. 1234 –1236 (3)
    The current gain β of a high-β heterojunction bipolar transistor is usually limited, at normal operating range, by the ratio of the injected electron current to the recombination current in the space-charge region. The Early effect in these transistors is very important because the base layer is very thin in order to obtain high β. In this case, the classical transistor models are not very suitable, and an Early voltage smaller than for a homojunction bipolar transistor is commonly observed. In the letter an analysis has been carried out taking into account the emitter current crowding effect and heterojunction characteristics. A simple analytic equation of the Early voltage is derived, and experimental results are presented.
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Thickness determination for silicon-on-insulator structures
  • Author(s): T.I. Kamins  and  J.P. Colinge
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1236 –1237
  • DOI:  10.1049/el:19860847
  • Type: Article
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  • p. 1236 –1237 (2)
    Optical interference at the interfaces of a silicon-on-insulator structure has been used for rapid, nondestructive determination of the silicon and oxide layer thicknesses. The technique is useful for determining the layer thicknesses for wafers in which devices and circuits are subsequently fabricated, especially for very thin silicon films in which the device characteristics depend strongly on the silicon thickness.
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Fibre couplers composed of unequal cores
  • Author(s): A.W. Snyder  and  A. Ankiewicz
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1237 –1238
  • DOI:  10.1049/el:19860848
  • Type: Article
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  • p. 1237 –1238 (2)
    To obtain the simplest results possible for couplers composed of nearly equal cores, terms of second order have been deliberately neglected in the previous conventional perturbation analysis. Merely by retaining these terms, we obtain the full perturbation results—results which satisfy power conservation exactly and which cannot be improved on within weak coupling. Our derivation shows that the recent ‘new thoery’ of Hardy and Streifer, which necessitates consideration of radiation, is convoluted, unnecessary and contains fundamental errors.
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Wideband 1.5μm optical receiver using travelling-wave laser amplifier
Quantum-well-doped FET (QUD-FET)
  • Author(s): K. Hikosaka ; S. Sasa ; Y. Hirachi
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1240 –1241
  • DOI:  10.1049/el:19860850
  • Type: Article
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  • p. 1240 –1241 (2)
    A novel FET using a 2DEG is presented. The FET has an AlAs/GaAs/AlAs single quantum well with planar doping in the centre of the GaAs layer. The conduction channels are composed of a 2DEG generated in undoped GaAs layers outside the well. The measured 2DEG concentration was 1.8–2 × 1012cm−2 with electron mobilities of 3500cm2/Vs at RT and 10500cm2/Vs at 77K. A 1.5μm-gate-length FET exhibits a maximum transconductance of 174 mS/mm and a maximum current exceeding 300 mA/mm at 77K.
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GaAs/AlGaAs directional coupler switch with submillimetre device length
Production of silicon oxides from glow discharge decomposition of silane and nitric oxide
Characteristics of separated-gate JFETs
Analysis of multiple-quantum-well distributed feedback laser
Cabled-fibre, 1.6Gbit/s, 1550nm transmission experiment
Application of coupled-mode theory to nearly parallel waveguide systems
  • Author(s): A. Hardy ; M. Osiński ; W. Streifer
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1249 –1250
  • DOI:  10.1049/el:19860856
  • Type: Article
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  • p. 1249 –1250 (2)
    The improved coupled-mode theory is extended and applied to multiwaveguide systems consisting of any number of nonparallel guides, such as Y-junction laser arrays and directional couplers. The impact of the improved analysis on the design of devices containing nonparallel sections is illustrated by an example of Ti-indiffused LiNbO3 directional couplers. It is shown that the overall performance of the device may be significantly affected by the nonparallel sections.
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Designing cellular parasitic-insensitive SC-ladder filters suitable for mask-programmable manufacture
  • Author(s): A. Kålin ; R. Sigg ; G.S. Moschytz
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1250 –1252
  • DOI:  10.1049/el:19860857
  • Type: Article
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  • p. 1250 –1252 (3)
    A systematic design technique for the well known LDI equivalent SC-ladder filter is described. The proposed scheme starts from an R-LC prototype that is specially synthesised for active SC simulation. Based on this prototype, our approach systematically leads to an SC realisation with identical loop cells. These are well suited for implementations where regular structures are desirable, such as mask-programmable filters.
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Performance of corrugated and dielectric-loaded metallic-conical horns
Dichroism evaluation in high-birefringence fibres by means of crosstalk measurements
Serial/parallel modules for complex arithmetic
  • Author(s): S.G. Smith
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1256 –1257
  • DOI:  10.1049/el:19860860
  • Type: Article
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  • p. 1256 –1257 (2)
    A serial/parallel architecture for complex arithmetic is described, based on a pair of carry-save accumulator arrays. In its basic form, the array pair forms a carry-save complex multiply/adder. By a simple modification to the coefficient store, the basic complex multiplier is given the capability to compute short complex inner products, thus extending a previously reported methodology for construction of real inner-product computers. The modules are easily cascaded to handle longer complex vectors. The use of distributed arithmetic eliminates redundant computation, resulting in considerable area savings over classical methods for integrated circuit realisations of complex arithmetic.
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Efficient ARQ with time diversity reception technique—a time diversity ARQ
  • Author(s): F. Adachi  and  S. Ito
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1257 –1258
  • DOI:  10.1049/el:19860861
  • Type: Article
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  • p. 1257 –1258 (2)
    A technique for increasing the efficiency of an ARQ system using time diversity reception is proposed fo mobile radio use. In this technique, the receiver demodulator output associated with each symbol is weighted and combined every time a new retransmission is made. Theoretical results show that this technique offers a considerable reduction in the average number of transmissions, in comparison with conventional ARQ systems.
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Laser-MESFET optoelectronic integration on GaAs: a simple technological process
  • Author(s): F. Brillouet ; A. Clei ; A. Kampfer ; S. Biblemont ; R. Azoulay ; N. Duhamel
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1258 –1260
  • DOI:  10.1049/el:19860862
  • Type: Article
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  • p. 1258 –1260 (3)
    A new simple technological process of laser-MESFET integration is described. In this process only a one-step MOCVD epitaxy schedule is used for the laser layer growth, and an implanted channel is employed for the MESFET. Integrated modules with a threshold current of 22 mA and an optical/ electrical conversion factor ΔP/ΔVG=9mW/V/facet are obtained.
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Optically induced drift effects in lithium niobate electro-optic waveguide devices operating at a wavelength of 1.51μm
Analysis of latch-up holding voltage for shallow trench CMOS
  • Author(s): R.K. Gupta ; I. Sakai ; C. Hu
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1261 –1263
  • DOI:  10.1049/el:19860864
  • Type: Article
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  • p. 1261 –1263 (3)
    We present an analysis of the latch-up holding voltage of CMOS devices using a lightly doped epitaxially grown layer over a heavily doped substrate, and a well isolation trench of varying depth. Using a simplified simulation scheme it is shown that there exists an optimum epilayer thickness which is somewhat greater than the well depth and leads to maximum holding voltage. Using a relatively shallow trench and with a proper choice of epitaxial layer thickness, the holding voltage can easily be raised above the power supply voltage, thus ensuring freedom from latch-up.
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Accurate calculation of depletion-layer profile in a periodic metal-semiconductor array
  • Author(s): H. Baudrand ; F. Brito ; M. Ahmadpanah
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1263 –1265
  • DOI:  10.1049/el:19860865
  • Type: Article
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  • p. 1263 –1265 (3)
    Poisson's equation is solved for two-dimensional calculation of the depletion-layer profile in a periodic array of metal-semiconductor contacts. Using Green's functions, which verify the specific boundary conditions of the structure's unit cell, an integral equation is obtained and the moment method is used for its numerical solution. At last empirical relations are deduced for the determination of characteristic points of the depleted region.
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621 nm CW operation (0%C) of AlGaInP visible semiconductor lasers
Indium tin oxide/GaAs photodiodes for millimetric-wave applications
Very high speed operation of planar InGaAs/InP photodiode detectors
  • Author(s): H. Temkin ; R.E. Frahm ; N.A. Olsson ; C.A. Burrus ; R.J. McCoy
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1267 –1269
  • DOI:  10.1049/el:19860868
  • Type: Article
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  • p. 1267 –1269 (3)
    Planar, diffused, InGaAs/InP PIN detectors have been optimised for high-speed operation. To minimise the junction capacitance the p-n junction diameter was reduced to 25 μn, resulting in operating chip capacitance as low as 20 fF. The relationship between the bandwidth and quantum efficiency was investigated by varying the thickness of the n-InGaAs absorbing layer, from 8μm down to 0.4 μm. Using optical heterodyning techniques, a response bandwidth ( −3dB) in excess of 20 GHz was demonstrated. The quantum efficiency of the fastest devices is 38% at 1.3 μm wavelength.
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Resonance in self-oscillating antennas
10 GHz frequency-convertor silicon bipolar MMIC
  • Author(s): I. Kipnis  and  A.P.S. Khanna
  • Source: Electronics Letters, Volume 22, Issue 23, p. 1270 –1271
  • DOI:  10.1049/el:19860870
  • Type: Article
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  • p. 1270 –1271 (2)
    A microwave self-oscillating mixer (SOM) functioning ax a frequency convenor with conversion gains up to 17dB at 5 GHz is reported. The SOM consists of an fr=10 GHz silicon bipolar monolithic microwave integrated circuit (MMIC) and a dielectric resonator (DR). It down-converts signals up to 9 GHz with conversion gain. The highest measured frequency of oscillation for a microstrip packaged device was 10.7 GHz.
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Erratum: Acousto-optic frequency shifting in ordinary single-mode fibre
Erratum: High return loss connector design without using fibre contact or index matching

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