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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 21, Issue 7, 28 March 1985

Volumes & issues:

Volume 21, Issue 7

28 March 1985

Modified residue calculus technique for microstrip step discontinuities
AlGaAs/GaAs Heterojunction bipolar power transistors
  • Author(s): B. Kim ; H.Q. Tserng ; S.K. Tiku ; H.D. Shih
  • Source: Electronics Letters, Volume 21, Issue 7, p. 258 –259
  • DOI:  10.1049/el:19850183
  • Type: Article
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  • p. 258 –259 (2)
    An AlGaAs/GaAs heterojunction bipolar transistor with a total emitter periphery of 320 μm has been developed for power amplifier applications. For the base contact, Zn diffusion was used to convert the n-type emitter material into p-type with a doping of ̃1.0 × 1020 cm−3. Because of the highly doped layer, contact resistivity was extremely low (5 × 10−7 Ωcm2). At 3 GHz, a CW output power of 320 mW with 7 dB gain and 30% power-added efficiency was obtained. Under pulsed operation, the output power increased to 500 mW with 6 dB gain and 40% power-added efficiency. With further device structure optimisations, the power performance of heterojunction bipolar transistors is expected to rival, or even surpass, that of the GaAs MESFETs.
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High-efficiency monolithic GaAs IMPATT diodes
  • Author(s): B. Bayraktaroglu  and  H.-D. Shih
  • Source: Electronics Letters, Volume 21, Issue 7, p. 259 –260
  • DOI:  10.1049/el:19850184
  • Type: Article
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  • p. 259 –260 (2)
    Impedance-matching circuits were integrated on the same chip as the IMPATT diodes to produce monolithic impatt diodes for millimetre-wave applications. A drastic reduction of device-to-circuit parasitic elements was achieved by placing the external circuitry very close to the device. Oscillators fabricated in this fashion gave the highest efficiencies reported so far in the 30–35 GHz range with 28% conversion efficiency using hybrid-Read structures.
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Detection of binary images in film grain noise
Improved very-high-speed packaged InGaAs PIN punch-through photodiode
Latched domino CMOS logic
Influence of amplitude-phase coupling on the injection locking bandwidth of a semiconductor laser
  • Author(s): P. Gallion  and  G. Debarge
  • Source: Electronics Letters, Volume 21, Issue 7, p. 264 –266
  • DOI:  10.1049/el:19850188
  • Type: Article
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  • p. 264 –266 (3)
    The strong amplitude-phase coupling in a semiconductor laser is well known to induce an enhancement linewidth factor (1 + α2) It is shown that it also produces an enhancement of the injection locking bandwidth proportional to (1 + α2)1/2. The connection with the usual locking bandwidth derived from Adler's equation is pointed out by considering the carrier dependence of the injected cavity resonance frequency.
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678 Mbaud optical transmission experiment through 37 km of PCVD graded-index fibre
  • Author(s): G. Appelhans ; W. Lackas ; G. Lampe
  • Source: Electronics Letters, Volume 21, Issue 7, p. 266 –267
  • DOI:  10.1049/el:19850189
  • Type: Article
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  • p. 266 –267 (2)
    A 5B6B line-coded 565 Mbit/s system designed for single-mode transmission at 1.3 μm wavelength was successfully operated through 37 km of state-of-the-art graded-index fibre (50/125 μm) made by PCVD process. With mean bandwidth values in excess of 1.5 GHz for the individual 2.18 km-long cable sections and a low concatenation factor (γ≃0.54), an overall fibre bandwidth of 400 MHz was achieved. The measured receiver sensitivity was −32.5 dBm for a 10−10 BER, showing a penalty of ≤3 dB compared to single-mode transmission.
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Long-span optical transmission experiment over 222.8 km of commercial monomode fibre at 140 Mbit/s and 1.525 μm
Error-rate floor in optical ASK heterodyne systems caused by nonzero (semiconductor) laser linewidth
  • Author(s): G. Jacobson  and  I. Garrett
  • Source: Electronics Letters, Volume 21, Issue 7, p. 268 –270
  • DOI:  10.1049/el:19850191
  • Type: Article
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  • p. 268 –270 (3)
    Using a simple model to account for the effects of non-negligible linewidths for the transmitter and local oscillator lasers in a heterodyne ASK system, we show that there is an error probability floor which is a function of the IF bandwidth and the relative decision threshold level. We describe the physical reason for this behaviour and present some calculated results for total error probability in terms of signal power, IF linewidth and bandwidth, and threshold setting. The implications of this ‘floor’ for practical receiver design are discussed.
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Complex permittivity of a dielectric mixture: corrected version of Lichtenecker's logarithmic law of mixing
Propagation characteristics of a triangular-index doubly clad monomode fibre
Bit rate dependence of receiver sensitivities in Ga0.47In0.53As photoconductive detectors
Design and manufacture of fibres with specific dispersion properties
Comment: Active-RC-circuit synthesis for the simulation of a grounded inductor
Reply: Active-RC-circuit synthesis for the simulation of a grounded inductor
Few parameter method for bandwidth prediction of a fibre chain
Hankel transform domain analysis of complex resonant frequencies of double-tuned circular disc microstrip resonators/radiators
Equivalent circuit of microstrip spiral inductor circuit generation by computer
Influence of (semiconductor) laser linewidth on the error-rate floor in dual-filter optical FSK receivers
  • Author(s): I. Garrett  and  G. Jacobsen
  • Source: Electronics Letters, Volume 21, Issue 7, p. 280 –282
  • DOI:  10.1049/el:19850201
  • Type: Article
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  • p. 280 –282 (3)
    We discuss an error-rate floor in dual-filter optical FSK receivers in terms of the IF linewidth and the frequency shift between 0s and 1s, using a comprehensive model for the receiver which takes into account nonzero laser linewidth, noise correlation and signal overlap between the filters. We present calculated results for total error probability in terms of signal power, IF linewidth and frequency shift, illustrating the effect of the floor on receiver sensitivity, and we contrast it with a related effect in heterodyne ASK systems.
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Improved Raman-fibre pulse delay measurement system
Realisation of flat FM response by directly modulating a phase tunable DFB laser diode
  • Author(s): S. Yamazaki ; K. Emura ; M. Shikada ; M. Yamaguchi ; I. Mito
  • Source: Electronics Letters, Volume 21, Issue 7, p. 283 –285
  • DOI:  10.1049/el:19850203
  • Type: Article
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  • p. 283 –285 (3)
    Flat and efficient FM responses in a wide frequency range were obtained by directly modulating the injection current of a 1.3 μm phase-tunable DFB-DC-PBH laser diode. The FM response is flat between 1 kHz and 300 MHz, and the nor malised frequency deviation is 1–3 GHz/mA, which is 5–10 times larger than that of a conventional laser diode in the several hundred megahertz region.
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Rearrangeable one-sided switching networks composed of uniform time-space elements
Effect of magnetic field on n+nn+ GaAs ballistic diode
Coupling of lasers to single-mode fibres with high efficiency and low optical feedback
  • Author(s): T. Schwander ; B. Schwaderer ; H. Storm
  • Source: Electronics Letters, Volume 21, Issue 7, p. 287 –289
  • DOI:  10.1049/el:19850206
  • Type: Article
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  • p. 287 –289 (3)
    A simple automatic method of obtaining tapered ends for single-mode fibres is by using a microcomputer-controlled process. In addition to producing standard tapers of more than 300 μm in length and radii of curvature of more than 20 μm at their tip, it is now possible to draw very short and pointed tapers (lengths <200 μm, radii <10 μm) resulting in very high launching efficiencies of about 75% with low optical feedback in the laser source.
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Efficient motion estimation for interframe video coding applications
CW pumped Raman preamplifier in a 45 km-long fibre transmission system operating at 1.5 μm and 1 Gbit/s
  • Author(s): J. Hegarty ; N.A. Olsson ; L. Goldner
  • Source: Electronics Letters, Volume 21, Issue 7, p. 290 –292
  • DOI:  10.1049/el:19850208
  • Type: Article
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  • p. 290 –292 (3)
    We describe direct Raman amplification by a CW pump of a distributed feedback semiconductor laser operating in the 1.5 μm low-loss region of a single-mode optical fibre, and at powers comparable to the spontaneous Raman scattering from the pump. A direct measure of the increase in receiver sensitivity from bit-error-rate measurements show an enhancement in the signal-to-noise ratio at these low signal powers.
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Design and performance of π guide directional couplers with very flat couplings
  • Author(s): J. Rodriguez  and  A. Prieto
  • Source: Electronics Letters, Volume 21, Issue 7, p. 292 –293
  • DOI:  10.1049/el:19850209
  • Type: Article
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  • p. 292 –293 (2)
    The use of the π guide is proposed for the construction of directional proximity couplers with a very flat response for the coupling. The dielectric configurations are analysed by Schelkunoff's method and the effective constant dielectric method. The introduction of metallic walls in a dielectric proximity coupler allows us to eliminate the additional couplings in the curved zones, couplings which depend heavily on the frequency, and reduce the radiation losses.
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Improved high-temperature performance of 1.52 (μm InGaAsP laser diodes fabricated by two-step VPE and LPE
Characterisation of single-mode optical fibres by measurement of equalisation wavelength
  • Author(s): J.L. McMillan  and  S.C. Robertson
  • Source: Electronics Letters, Volume 21, Issue 7, p. 295 –296
  • DOI:  10.1049/el:19850211
  • Type: Article
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  • p. 295 –296 (2)
    A new technique for characterising single-mode optical fibres is described. Having performed a single numerical computation for a specific fibre type, and having obtained empirically the length dependence of the effective cutoff wavelength for that fibre type, coating type and cable structure, then a measurement of equalisation wavelength on any fibre of the same type will enable the V-value to be related to wavelength. It will also allow prediction of the effective cutoff wavelength for that fibre type, coating type and cable structure.
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Binary error probabilities on Earth-space links subject to scintillation fading
  • Author(s): O.P. Banjo  and  E. Vilar
  • Source: Electronics Letters, Volume 21, Issue 7, p. 296 –297
  • DOI:  10.1049/el:19850212
  • Type: Article
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  • p. 296 –297 (2)
    Theoretical estimates are derived of the average probability 〈Pb〉 of bit error rate that would occur for a binary CPSK signal on an Earth-space link in the presence of scintillation fading and additive white Gaussian noise. Strong scintillations are shown to produce a significant degradation in 〈Pb〉. Experimental results of the signal amplitude distribution obtained on a 7.1° elevation satellite downlink lead to values of 〈Pb〉 against 〈Eb/No〉 which agree well with the results obtained using the theoretical Moulsley-Vilar distribution (1982).
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High-frequency modulation of 1.52 μm vapour-phase-transported InGaAsP lasers
Surface electrical breakdown and leakage current on semi-insulating InP
Rectangular-transform-based adaptive filter
GaInAsP/InP surface emitting laser (λ = 1.4 μm, 77 K) with heteromultilayer Bragg reflector
  • Author(s): A. Chailertvanitkul ; K. Iga ; K. Moriki
  • Source: Electronics Letters, Volume 21, Issue 7, p. 303 –304
  • DOI:  10.1049/el:19850216
  • Type: Article
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  • p. 303 –304 (2)
    50 layers of GaInAsP/InP heteromultistructure with one quarter-wavelength thickness have been fabricated by computer-controlled rotational LPE. The measured reflectivity of the Bragg reflector was 82% at λ = 1.4 μm. The application of the multilayer as a reflector to a surface-emitting laser is demonstrated and a first GaInAsP/InP surface-emitting laser (λ = 1.4 μm) with a heteromultilayer Bragg reflector has been realised. The pulsed threshold current was 120 mA at 77 K and single-wavelength oscillation has been achieved.
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Microstrip microslot antennas for biomedical applications: frequency analysis of different parameters of this type of applicator
Planar MOCVD GaAlAs/GaAs high-frequency mixer diodes
Modal noise reduced PFM transmission by monopulse to twin-pulse conversion
Novel high-speed In0.53 Ga0.47As/InP lateral phototransistor
  • Author(s): N. Chand ; P.A. Houston ; P.N. Robson
  • Source: Electronics Letters, Volume 21, Issue 7, p. 308 –310
  • DOI:  10.1049/el:19850220
  • Type: Article
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  • p. 308 –310 (3)
    A novel structure for a very small area In0.53 Ga0.47As/InP phototransistor on a semi-insulating InP substrate is proposed for single-mode fibre optic communication applications. An optical gain of 38 at 64 μW incident power was measured on the first batch of unoptimised devices. The emitter-base and base-collector junction areas were 50 and 100 μm2 respectively. Pulse response measurements using a picosecond dye laser indicated a rise time of 100 ps and a FWHM of 180 ps.
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