Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 23, Issue 11, 21 May 1987
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Volume 23, Issue 11
21 May 1987
Josephson vortex timing circuit
- Author(s): K. Aihara ; K. Miyahara ; K. Hohkawa
- Source: Electronics Letters, Volume 23, Issue 11, p. 545 –546
- DOI: 10.1049/el:19870391
- Type: Article
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We have studied a new timing circuit in which the input signal is put out at the same time as the clock signal. This is a key element for the realisation of Josephson vortex logic. We propose a new device structure which consists of two Josephson transmission lines connected by a resistor and a vortex trapping site (VTS). In this device a signal vortex is trapped in the VTS and it is repropagated to the output when the clock signal vortex propagates to the turning point. The quasistatic operation of this device is confirmed experimentally.
1.3μm InGaAsP/InP distributed-feedback P-substrate partially inverted buried-heterostructure laser diode
- Author(s): A. Takemoto ; Y. Sakakibara ; Y. Nakajima ; M. Fujiwara ; S. Kakimoto ; H. Namizaki ; W. Susaki
- Source: Electronics Letters, Volume 23, Issue 11, p. 546 –547
- DOI: 10.1049/el:19870392
- Type: Article
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–547
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A novel 1.3μm InGaAsP/lnP distributed-feedback buried-heterostructure laser diode on p-type InP substrate has been developed utilising a dopant diffusion technique. The laser has achieved a threshold current as low as 20 mA and high output power of 32 mW under CW and SLM operation.
Computer simulation of SC circuits using NAP
- Author(s): S. Osowski
- Source: Electronics Letters, Volume 23, Issue 11, p. 547 –549
- DOI: 10.1049/el:19870393
- Type: Article
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The adaptation of the NAP program to the frequency analysis of SC circuits is presented in the letter. According to this approach the equivalent circuit contains resistances and inductances or capacitances as the representations of the switched or unswitched capacitors in the frequency domain.
Voltage-fed transistorised induction heating power supply
- Author(s): S. Hinchliffe and L. Hobson
- Source: Electronics Letters, Volume 23, Issue 11, p. 549 –551
- DOI: 10.1049/el:19870394
- Type: Article
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A prototype voltage-fed MOSFET power supply for highfrequency induction heating applications is described. Special emphasis is given to the protection circuitry required.
Novel circuit design and implementation of adaptive phase comparators
- Author(s): J.C. Haartsen and R.C. Den Dulk
- Source: Electronics Letters, Volume 23, Issue 11, p. 551 –552
- DOI: 10.1049/el:19870395
- Type: Article
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–552
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A novel circuit implementation for an adaptive phasefrequency comparator, which can be conceived of as a 5-cell up-down counter, is proposed. This circuit can handle coincident input signals and has no dead phase zone or intermediate states. These properties greatly improve the performance of a phase-locked loop.
Nonlinear thermal effects in thin-film conductors on insulating substrates
- Author(s): D. de Cogan and M. Henini
- Source: Electronics Letters, Volume 23, Issue 11, p. 552 –554
- DOI: 10.1049/el:19870396
- Type: Article
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A transmission-line treatment of heat flow in thin-film electric conductors on insulating substrates has confirmed that the temperature dependence of parameters such as metal resistance as well as metal and insulator specific heat and thermal conductivity should be included in any reliable model. The co-operative contribution of these nonlinearities determines the maximum temperature-time relationships. The results have important consequences for substrate electric fuses and for the transient ratings of silicon power devices.
Compact formulation for exact analysis of nonideal SC circuits
- Author(s): M. Sanz and A. Puerta
- Source: Electronics Letters, Volume 23, Issue 11, p. 554 –555
- DOI: 10.1049/el:19870397
- Type: Article
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A systematic analysis procedure to obtain closed-form expressions for the z-domain transfer functions of SC circuits with finite GB product op-amps is presented. This method allows exact frequential analysis of a general class of SC circuits, without imposing any restriction in the ratio between GB and clock frequencies.
Scanning the laser gain spectrum using distributed feedback and hydrostatic pressure
- Author(s): K.C. Heasman ; A.R. Adams ; R.G. Plumb
- Source: Electronics Letters, Volume 23, Issue 11, p. 555 –557
- DOI: 10.1049/el:19870398
- Type: Article
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High-pressure measurements on distributed-feedback GaxIn1-xASyP1-y lasers allow the gain spectrum to be scanned, providing a powerful tool for the study of the intrinsic properties of the laser, including the mechanisms responsible for the high-temperature sensitivity.
Efficiency of block error-correcting codes
- Author(s): S.G. Glisic
- Source: Electronics Letters, Volume 23, Issue 11, p. 557 –558
- DOI: 10.1049/el:19870399
- Type: Article
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Recently, a novel criterion for digital synchronous communication system efficiency estimation has been defined. Using this criterion in the letter we analyse the efficiency of block error-correcting codes.
Public-key cryptosystem based on the difficulty of solving a system of nonlinear equations
- Author(s): S. Tsujii ; T. Itoh ; A. Fujioka ; K. Kurosawa ; T. Matsumoto
- Source: Electronics Letters, Volume 23, Issue 11, p. 558 –560
- DOI: 10.1049/el:19870400
- Type: Article
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–560
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The letter proposes a new public-key cryptosystem which requires O(m2) operations for encryption/decryption (m is the message bit length) and also realises digital signatures. Two possible attacking methods to break the proposed cryptosystem are considered, and consequently the cryptosystem seems to be highly reliable.
New public-key distribution systems
- Author(s): Yang Yi Xian
- Source: Electronics Letters, Volume 23, Issue 11, p. 560 –561
- DOI: 10.1049/el:19870401
- Type: Article
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A few new public-key distribution systems are proposed in the letter. All these new systems are generalised to conference key distribution systems (CKDSs).
Homomorphic vector quantisation
- Author(s): R. Vích
- Source: Electronics Letters, Volume 23, Issue 11, p. 561 –562
- DOI: 10.1049/el:19870402
- Type: Article
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A new approach is proposed for vector quantisation in linear predictive speech coding. The problem is formulated as speech model recognition by minimising the Euclidean distance measure of real cepstra of models with unit power transmission. The procedure is robust with respect to quantisation of both the cepstral coefficients and operational results.
Novel process for emitter-base-collector self-aligned heterojunction bipolar transistor using a pattern-inversion method
- Author(s): S. Tanaka ; M. Madihian ; H. Toyoshima ; N. Hayama ; K. Honjo
- Source: Electronics Letters, Volume 23, Issue 11, p. 562 –564
- DOI: 10.1049/el:19870403
- Type: Article
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A process for base-emitter-collector self-aligned HBTs using a pattern-inversion method is presented. A fabricated HBT has an emitter with a size of 1.5 × 10μm2 realised by employing a dry-etching method. Typical current gain for the fabricated HBT is 26.
Microwave tomography: an algorithm for cylindrical geometries
- Author(s): J.M. Rius ; M. Ferrando ; L. Jofre ; E. de Los Reyes ; A. Elias ; A. Broquetas
- Source: Electronics Letters, Volume 23, Issue 11, p. 564 –565
- DOI: 10.1049/el:19870404
- Type: Article
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–565
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The letter presents an efficient algorithm in cylindrical coordinates for microwave diffraction tomography. In comparison with algorithms in cartesian co-ordinates, the mechanical rotation of the object is avoided and higher-quality images are obtained with similar processing time.
Efficient calculation of partial derivatives in nonlinear conductances driven by periodic input signals
- Author(s): C. Camacho-Peñalosa ; L. Mariscal-Rico ; A. Alonso-Pardo
- Source: Electronics Letters, Volume 23, Issue 11, p. 565 –566
- DOI: 10.1049/el:19870405
- Type: Article
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Expressions for calculating current derivatives efficiently with respect to voltage in nonlinear conductances under periodic excitation are derived. The validity of Egami's approach for computing these derivatives is discussed.
Improved AlGaAs/GaAs HBT performance by InGaAs emitter cap layer
- Author(s): K. Nagata ; O. Nakajima ; T. Nittono ; H. Ito ; T. Ishibashi
- Source: Electronics Letters, Volume 23, Issue 11, p. 566 –568
- DOI: 10.1049/el:19870406
- Type: Article
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The effects of the emitter resistance reduction on the DC and high-frequency characteristics in an AIGaAs/GaAs HBT with an InGaAs emitter cap layer are investigated. In fabricated devices, a transconductance per unit area of 16mS/μm2 and a cutoff frequency of 80 GHz have been achieved.
Accuracy of Fabry-Perot method of semiconductor laser gain measurement
- Author(s): M.B. El Mashade and J. Arnaud
- Source: Electronics Letters, Volume 23, Issue 11, p. 568 –570
- DOI: 10.1049/el:19870407
- Type: Article
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The Fabry–Perot (FP) method of semiconductor laser gain measurement, first proposed by Hakki and Paoli (1975), is widely used. It is based on the measurement of the FP resonances excited by spontaneous emission. Its validity rests on the assumption that a single mode is significant. We show, using a simplified laser model, that this assumption is valid only when the power mirror reflectivity is very small, or near the laser oscillating frequency. For example, the error is in the order of 20% when the power facet reflectivities are equal to 37% and the modal gain is unity. These results apply to both index-guided and gain-guided lasers.
Effect of facet coatings on far fields of semiconductor lasers
- Author(s): T. Ohtoshi
- Source: Electronics Letters, Volume 23, Issue 11, p. 570 –571
- DOI: 10.1049/el:19870408
- Type: Article
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A theoretical expression is derived for the far fields of semiconductor lasers with coated facets. It is shown that the far fields are different for uncoated, antireflection-coated and high-reflection-coated lasers. The correction factor for the far fields is shown to depend on the transmission coefficient of the facets.
High-speed, self-passivated InGaAs PIN photodiode for microwave fibre links
- Author(s): C. Fan ; P.K.L. Yu ; P.C. Chen
- Source: Electronics Letters, Volume 23, Issue 11, p. 571 –572
- DOI: 10.1049/el:19870409
- Type: Article
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–572
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High-speed, low-dark-current, front-side-illuminated InGaAs PIN photodiodes with a self-passivated-mesa structure have been fabricated on semi-insulating InP substrates. These detectors have a nearly flat frequency response beyond 22GHz. Their quantum efficiency is 65% without AR coating and the dark current is about 5nA at –10V.
Electro-optically tunable, narrowband Ti:LiNbO3 wavelength filter
- Author(s): F. Heismann ; L.L. Buhl ; R.C. Alferness
- Source: Electronics Letters, Volume 23, Issue 11, p. 572 –574
- DOI: 10.1049/el:19870410
- Type: Article
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We report a tunable optical transmission filter for 1.5μn with a bandwidth of 12 Å and a tuning range of at least 80 Å. The filter is based on wavelength-dependent polarisation conversion in a birefringent waveguide and employs a periodic electrode structure with interleaved birefringence tuning electrodes.
Monolithically integrated, photoreceiver with large, gain-bandwidth product
- Author(s): S.J. Wojtczuk ; J.M. Ballantyne ; Y.K. Chen ; S. Wanuga
- Source: Electronics Letters, Volume 23, Issue 11, p. 574 –576
- DOI: 10.1049/el:19870411
- Type: Article
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A direct-detection 800 nm GaAs monolithically integrated photoreceiver is reported with a photocurrent gain of 200 and a 1 GHz bandwidth capable of driving a 50 Ω load with IV peak pulses. The integrated NPN photodiode has over 7GHz bandwidth and requires no modifications to the ion-implanted GaAs MESFET process. The 200GHz gain-bandwidth product and 3200 V/W responsivity are among the highest reported for similar receivers.
CMOS on local SOI using SIMOX technology
- Author(s): S. Matsumoto ; T. Ohno ; K. Izumi
- Source: Electronics Letters, Volume 23, Issue 11, p. 576 –577
- DOI: 10.1049/el:19870412
- Type: Article
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CMOS on local SOI, in which n-MOS/bulk and p-MOS/SOI can be selectively implemented on the same chip, has been developed. SOI regions are formed by SIMOX technology, while bulk regions are prepared by etching of the buried SiO2. A CMOS inverter fabricated on local SOI shows good transfer characteristics.
Analysis of bilateral finline couplers
- Author(s): D. Mirshekar-Syahkal and B. Jia
- Source: Electronics Letters, Volume 23, Issue 11, p. 577 –579
- DOI: 10.1049/el:19870413
- Type: Article
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Although characteristics of bilateral finline as a transmission line have been studied in detail, the behaviour of this structure as a coupler has not received much attention so far. The letter represents a study of phase constants and characteristic impedances of the even and odd modes of bilateral finlines as couplers, leading to the exposition of some useful design information.
Comment on published carrier lifetime data on silicon-on-insulator (SOI) materials
- Author(s): K. Das
- Source: Electronics Letters, Volume 23, Issue 11, page: 579 –579
- DOI: 10.1049/el:19870414
- Type: Article
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Reply to: Comment on published carrier lifetime data on silicon-on-insulator (SOI) materials
- Author(s): W. Skorupa
- Source: Electronics Letters, Volume 23, Issue 11, page: 579 –579
- DOI: 10.1049/el:19870415
- Type: Article
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Semiparallel microelectronic implementation of neural network models using CCD technology
- Author(s): A. Agranat and A. Yariv
- Source: Electronics Letters, Volume 23, Issue 11, p. 580 –581
- DOI: 10.1049/el:19870416
- Type: Article
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A new generic architecture for realising the basic functions of neural networks is described. In the proposed configuration the N × N interconnectivity problem is accomplished by a simultaneous combination of horizontal and vertical shifting of CCD arrays. The proposed devices can be implemented with present-day technologies.
YAG resonator
- Author(s): E. Dieulesaint ; D. Mazerolle ; D. Royer
- Source: Electronics Letters, Volume 23, Issue 11, p. 581 –582
- DOI: 10.1049/el:19870417
- Type: Article
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A resonator made of a YAG rod has been excited, in an extensional mode, by the capacitive effect. An alternating voltage was applied across a capacitor formed by one of the free metallised ends of the rod and a fixed metal plate placed at a short distance. A Q-factor of 1.9×106 was measured at the resonance frequency of 195.76 kHz.
Low-loss and lightweight on-board 20 GHz-band pill-box-type directional filter
- Author(s): I. Ohtomo and H. Kumazawa
- Source: Electronics Letters, Volume 23, Issue 11, p. 582 –583
- DOI: 10.1049/el:19870418
- Type: Article
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An on-board channel multiplexer using pill-box-shaped TM310 travelling-wave cavities with high unloaded Q-factor has been developed in the 20 GHz band. The measured branching loss of a three-cavity filter is 0.27 dB at a resonant frequency of 19.99 GHz. The weight of the filter made of thin-walled super-Invar is 71 g. Its size is 4.5×4.6×5.1 cm.
Ray analysis of mutual coupling between antennas on a general paraboloid of revolution (GPOR)
- Author(s): R.M. Jha ; V. Sudhakar ; N. Balakrishnan
- Source: Electronics Letters, Volume 23, Issue 11, page: 583 –583
- DOI: 10.1049/el:19870419
- Type: Article
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A methodology has been presented for the first time for computing geometric parameters of a GPOR, necessary for applying high-frequency techniques to antenna analysis. The analytical expressions for the geometric parameters derived here could be readily applied to mutual coupling problems.
Observation of voltage contrast in scanning ion microscopy of integrated circuits
- Author(s): E.C.G. Kirk ; J.R.A. Cleaver ; H. Ahmed
- Source: Electronics Letters, Volume 23, Issue 11, p. 585 –586
- DOI: 10.1049/el:19870420
- Type: Article
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Strong voltage contrast effects have been observed in scanning ion microscopy of integrated circuits. The ion beam has also been used to cut microsections in integrated circuits, with precise control of position and depth. The voltage distributions in these sections can be observed.
Efficient choice of basis functions in moment method analysis of frequency-selective surfaces
- Author(s): R. Orta ; R. Tascone ; R. Zich
- Source: Electronics Letters, Volume 23, Issue 11, p. 586 –587
- DOI: 10.1049/el:19870421
- Type: Article
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A key point in the scattering analysis of frequency-selective surfaces (FSSs) by the method of moments is the selection of a convenient set of basis functions. A new set is presented, which allows significant computer time saving and can be used in a wide range of geometrical parameters. The results of a parametric study performed by using this set are presented and discussed.
Sensitivity of GaAs analogue integrated circuit building blocks to the effect of back-gating
- Author(s): W.S. Lee
- Source: Electronics Letters, Volume 23, Issue 11, p. 587 –589
- DOI: 10.1049/el:19870422
- Type: Article
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The effects of back-gating on two basic GaAs precision analogue circuit building blocks have been established. Owing to internal gain, the stability of the single-stage inverter amplifier was found to be most susceptible to both positive and negative side-contact potentials, and the generation of low-frequency oscillations. The use of negative feedback to improve DC stability was demonstrated. In contrast, the source-follower exhibited relatively better stability against back-gating.
Quasi-instantaneous (<20ps) phase locking in single-lobe y-coupled laser diode arrays
- Author(s): R.K. Defreez ; R.A. Elliott ; K. Hartnett ; D.F. Welch
- Source: Electronics Letters, Volume 23, Issue 11, p. 589 –590
- DOI: 10.1049/el:19870423
- Type: Article
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The time evolution of the far-field radiation pattern of an in-phase locked Y-coupled diode laser array has been observed with a streak camera. A strong central lobe 2.3° wide with faint secondary sidelobes separated by 15° forms in a time less than 20 ps. This indicates that the elements of the array are instantaneously locked in-phase.
Fabrication of first-order gratings for 1.5 μm DFB lasers by high-voltage electron-beam lithography
- Author(s): M.J. Fice ; H. Ahmed ; S. Clements
- Source: Electronics Letters, Volume 23, Issue 11, p. 590 –592
- DOI: 10.1049/el:19870424
- Type: Article
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First-order gratings for 1.5 μm-wavelength distributed-feedback lasers have been fabricated reproducibly in InGaAsP by a combination of electron-beam lithography and wet-chemical etching. A high-voltage electron beam (60 kV) of small diameter (50 nm) is employed in the exposure step.
DFB ridge waveguide lasers at λ = 1.5 μm with first-order gratings fabricated using electron beam lithography
- Author(s): C.J. Armistead ; B.R. Butler ; S.J. Clements ; A.J. Collar ; D.J. Moule ; S.A. Wheeler ; M.J. Fice ; H. Ahmed
- Source: Electronics Letters, Volume 23, Issue 11, p. 592 –593
- DOI: 10.1049/el:19870425
- Type: Article
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DFB ridge waveguide lasers at λ = 1.53 μm have been fabricated with uniform first-order gratings defined using electron beam lithography. After MOCVD overgrowth of the grating and fabrication of the ridge waveguides the devices have shown thresholds as low as 22 mA and operation in a single longitudinal mode to powers greater than 10 mW. These results demonstrate that electron beam lithography can be successfully used for the fabrication of DFB lasers with the fine pitch required for first-order gratings.
Fabrication of twin-rectangular-cored fibre couplers
- Author(s): M. Green and T.J. Tate
- Source: Electronics Letters, Volume 23, Issue 11, p. 593 –595
- DOI: 10.1049/el:19870426
- Type: Article
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The concept, fabrication and characteristics of a novel fibre coupler are described. Twin, rectangular-cored fibre, made from silicate glasses, is sensitive to outer cladding refractive index, and has advantages in fabrication and use.
Optical third-harmonic generation from polydiacetylene thin films deposited by vacuum evaporation
- Author(s): S. Tomaru ; K. Kubodera ; S. Zembutsu ; K. Takeda ; M. Hasegawa
- Source: Electronics Letters, Volume 23, Issue 11, p. 595 –596
- DOI: 10.1049/el:19870427
- Type: Article
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Third-harmonic generation measurements have been made on polydiacetylene thin films fabricated by vacuum deposition. The third-order susceptibility was evaluated to be X(3) = 1.4 × 10-11 esu at 1.9 μm wavelength.
Reflectively tapped optical fibre transversal filters
- Author(s): C.-E. Lee ; R.A. Atkins ; H.F. Taylor
- Source: Electronics Letters, Volume 23, Issue 11, p. 596 –598
- DOI: 10.1049/el:19870428
- Type: Article
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A continuous length of silica fibre containing dielectric mirrors produced by a novel fusion-splicing technique is used in demonstrating delay-line signal processors.
Design for single-mode asymmetric quarter-wavelength-shifted DFB laser with high differential efficiency
- Author(s): H. Soda ; H. Ishikawa ; H. Imai
- Source: Electronics Letters, Volume 23, Issue 11, p. 598 –599
- DOI: 10.1049/el:19870429
- Type: Article
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An asymmetric quarter-wavelength-shifted DFB laser which has high differential efficiency and a large threshold gain difference under high-power operation has been designed taking the spatial hole-burning effect into account. The optimum kL was found to be about 1.4 in the laser, which has an asymmetry S/L of 0.15, where S is the distance from the centre to the phase shift position and L is the laser length.
Outage probability calculations for a mobile radio system having multiple Rayleigh interferers
- Author(s): K.W. Sowerby and A.G. Williamson
- Source: Electronics Letters, Volume 23, Issue 11, p. 600 –601
- DOI: 10.1049/el:19870430
- Type: Article
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Outage probability calculations are presented for the case when the transmission from a wanted base station is received by a mobile in the presence of several interfering cochannel signals. The calculations are limited to Rayleigh fading only and consider the need to achieve simultaneously both a sufficient SNR and SIR to obtain satisfactory radio reception.
CW performance and life of 1.3μm InGaAsP/InP lasers emitting at high facet power densities
- Author(s): R.F. Murison ; A.J.N. Houghton ; A.R. Goodwin ; A.J. Collar ; I.G.A. Davies
- Source: Electronics Letters, Volume 23, Issue 11, p. 601 –603
- DOI: 10.1049/el:19870431
- Type: Article
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Individual stripe InGaAsP/lnP lasers emitting in a single spatial mode have been operated for times in excess of 7000 h at constant output power levels up to 40 mW (NA 0.5) with no significant increase in drive current and at 60 mW (NA 0.5) with drive current increases of typically 1.2%/1000h. Units have been operated short-term at values of output power and facet flux density of 263 mW and 20MW/cm2, respectively, and life-tested at a constant power of 90 mW (NA 0.5) for times in excess of 6300 h. These results demonstrate the resistance of this laser material to facet degradation, and show a clear advantage over GaAlAs/GaAs lasers of comparable structure which typically show catastrophic facet damage at flux densities of 2–4 MW/cm2.
Two-dimensional FIR digital filters designed to arbitrary group-delay specifications
- Author(s): E. Sharestani and L.G. Cuthbert
- Source: Electronics Letters, Volume 23, Issue 11, p. 603 –604
- DOI: 10.1049/el:19870432
- Type: Article
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The letter describes a method for designing 2-dimensional FIR digital filters to an arbitrary group-delay, as well as gain, specification. Examples are given of filters designed using this approach.
p-type modulation-doped AlGaAs/GaAs heterostructures grown by atmospheric-pressure metal organic vapour phase epitaxy (MOVPE)
- Author(s): J.S. Roberts ; J. Woodhead ; P. Mistry ; K.C. Singh ; C.M. Sotomayor-Torres
- Source: Electronics Letters, Volume 23, Issue 11, p. 605 –606
- DOI: 10.1049/el:19870433
- Type: Article
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Atmospheric-pressure MOVPE has been used to prepare unintentionally doped Al0.6Ga0.4As/GaAs heterostructures which support a high-quality two-dimensional hole gas (2-DHG). p-type doping of the Al0.6Ga0.4As layer was achieved with the residual carbon background characteristic of the trimethylaluminium precursor. A hole concentration of 1.55 (±0.15) × 1012cm−2 has been measured by both the quantum Hall effect and Van der Pauw measurement with a mobility up to 6000cm2 V−1s−1 at 2K. Parallel conduction has been eliminated from the structure by incorporating an n-type Al0.45Ga0.55As buffer rather than a similar layer unintentionally doped p-type.
Probe compensation in thick microstrip patches
- Author(s): P.S. Hall
- Source: Electronics Letters, Volume 23, Issue 11, p. 606 –607
- DOI: 10.1049/el:19870434
- Type: Article
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In thick microstrip patches, probe inductance prevents matching of the patch impedance to the input connector. The probe inductance can be tuned out with a capacitive gap. To maintain simplified construction the gap is here etched on the patch surface. Bandwidths equal to or greater than that theoretically predicted are realised. Use of a single probe-compensated feed results in radiation pattern distortion, high crosspolarisation and low efficiency due both to higher-order modes and surface-wave generation. Two-probe feeding is used here to overcome these problems and to give a wide-band antenna with good radiation pattern control and high efficiency.
Erratum: Fast computation of discrete cosine transform through fast Hartley transform
- Author(s): H. Malvar
- Source: Electronics Letters, Volume 23, Issue 11, page: 608 –608
- DOI: 10.1049/el:19870435
- Type: Article
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608
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