Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 33, Issue 22, 23 October 1997
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Volume 33, Issue 22
23 October 1997
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- Author(s): L. Ravezzi ; D. Stoppa ; G.-F. Dalla Betta
- Source: Electronics Letters, Volume 33, Issue 22, p. 1829 –1830
- DOI: 10.1049/el:19971250
- Type: Article
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A simple modification to an existing current comparator is proposed, which enables a very low response time to be achieved with a minimal increase in circuit complexity. Circuit simulations allowed the design approach to be validated and the comparator performance to be compared to those of two other existing comparators.
Simple high-speed CMOS current comparator
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- Author(s): D. Singh ; P. Gardner ; P.S. Hall
- Source: Electronics Letters, Volume 33, Issue 22, p. 1830 –1831
- DOI: 10.1049/el:19971240
- Type: Article
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A novel miniaturised quarter wavelength, H-shaped antenna which will find applications in monolithic microwave integrated circuit (MMIC) design is presented. The antenna occupies approximately one tenth of the substrate area of a half wavelength patch antenna. The effect on the resonance frequency, bandwidth and gain of the antenna are reported. - Author(s): R.B. Waterhouse
- Source: Electronics Letters, Volume 33, Issue 22, p. 1831 –1832
- DOI: 10.1049/el:19971241
- Type: Article
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A printed antenna consisting of an annular ring coupled to a shorted patch is presented. The size of the antenna is compatible with typical mobile communications handset terminals and its impedance bandwidth satisfies the requirements for such systems as broadband personal communications systems (PCS). - Author(s): Kin-LuWong and Jian-YiWu
- Source: Electronics Letters, Volume 33, Issue 22, p. 1833 –1834
- DOI: 10.1049/el:19971299
- Type: Article
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The design of a single-feed small microstrip antenna with circular polarisation (CP) radiation is described. This design is achieved by cutting slits in the square patch and, by adjusting the lengths of the slits, the microstrip antenna can perform CP radiation with a reduced patch size at a fixed operating frequency. This design also provides a wide CP bandwidth and relaxed fabrication tolerances. - Author(s): A. Trucco ; E. Omodei ; P. Repetto
- Source: Electronics Letters, Volume 33, Issue 22, p. 1834 –1835
- DOI: 10.1049/el:19971261
- Type: Article
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A synthesis method is proposed that is aimed at designing a planar, sparse, and aperiodic array to be used in a beamforming processor. This method minimises the number of elements able to generate a beam pattern that fulfils various a priori fixed constraints. The obtained results are better than those proposed in related literature. - Author(s): I. Linardou ; C. Migliaccio ; J.M. Laheurte ; A. Papiernik
- Source: Electronics Letters, Volume 33, Issue 22, p. 1835 –1837
- DOI: 10.1049/el:19971259
- Type: Article
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The authors describe twin Vivaldi antennas directly fed by a coplanar waveguide. They have been designed and measured for various angles between the radiating slots. All the designs show a centred zero in the E plane with a low cross-polarisation. In the H plane they provide zeros for phis = 90° and 270° and are omnidirectional for other values.
Miniaturised microstrip antenna for MMIC applications
Printed antenna suitable for mobile communication handsets
Single-feed small circularly polarised square microstrip antenna
Synthesis of sparse planar arrays
Twin Vivaldi antenna fed by coplanar waveguide
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- Author(s): Chip-HongChang and B.J. Falkowski
- Source: Electronics Letters, Volume 33, Issue 22, p. 1837 –1838
- DOI: 10.1049/el:19971290
- Type: Article
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An efficient algorithm is presented for the calculation of any generalised spectrum represented as an algebraic decision diagram (ADD) from an ordered binary decision diagram (OBDD) of a Boolean function, and vice versa. - Author(s): G. Golo and Č. Milosavljević
- Source: Electronics Letters, Volume 33, Issue 22, p. 1838 –1839
- DOI: 10.1049/el:19971282
- Type: Article
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On the basis of the theory of variable structure systems, a new method for the synthesis of high-quality triangular wave oscillators has been proposed. The proposed oscillator features a finite oscillation build-up time, and the negative influence of the high-frequency control signal on the quality of output signals, chattering, is eliminated.
Efficient symbolic computation of generalised spectra
Two-phase triangular wave oscillator based on discrete-time sliding mode control
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- Author(s): Jian-GuoZhang ; Wing C.Kwong ; A.B. Sharma
- Source: Electronics Letters, Volume 33, Issue 22, p. 1840 –1841
- DOI: 10.1049/el:19971279
- Type: Article
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2n modified prime codes are designed for all-optical code-division multiple access (CDMA) networks using very simple encoders and decoders. The proposed code is obtained from an original 2n prime code of prime number P, by padding P – 1 zeros in each ‘subsequence’ of codewords in the corresponding 2n prime code. The cross-correlation constraint of the resulting 2n modified prime code is equal to one, as opposed to two for a 2n prime code. For a given bit error rate (BER), the proposed code can thus be used to support a larger number of active users in the fibre optic CDMA network than a 2n prime code. Moreover, using the former can also reduce code length and weight compared with employing the latter to achieve the same BER. - Author(s): L. Favalli ; A. Mecocci ; P. Savazzi
- Source: Electronics Letters, Volume 33, Issue 22, p. 1841 –1842
- DOI: 10.1049/el:19971269
- Type: Article
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The authors describe a novel approach to the problem of fading channels estimation. Specifically, the proposed system makes use of fuzzy logic in the computation of the metrics for an MLSE equaliser for GMSK signals in GSM typical environments. A comparison with the traditional Viterbi algorithm shows that the proposed system performs better under all channel conditions; for the same SNR, the improvement is about a half decade in BER or, conversely, the same BER can be obtained with an SNR 4 dB lower than using the adaptive Viterbi algorithm alone. - Author(s): A. Kourtis and Ch. Mantakas
- Source: Electronics Letters, Volume 33, Issue 22, p. 1843 –1844
- DOI: 10.1049/el:19971280
- Type: Article
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The authors describe and justify the configuration adopted in a large scale real condition trial, of a wireless cellular interactive network at 42 GHz, realised in the frame of an E.U. ACTS program, in the area of Athens. - Author(s): Jong-SooSeo and Il-KeunPark
- Source: Electronics Letters, Volume 33, Issue 22, p. 1844 –1846
- DOI: 10.1049/el:19971294
- Type: Article
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The performance of a low complexity correlation receiver for a rate variable SQAM modem is analytically and experimentally studied. It is found that the proposed receiver performs well for a range of SQAM signals by adjusting the amplitude parameter ‘B’ of the receive correlation pulse. The authors demonstrate that the suggested SQAM receiver would be very well suited for use in low cost as well as bandwidth and power limited satellite broadcasting systems such as a data broadcasting USAT (ultra small aperture terminal) network. - Author(s): F. Beritelli ; S. Casale ; A. Cavallaro
- Source: Electronics Letters, Volume 33, Issue 22, p. 1846 –1847
- DOI: 10.1049/el:19971289
- Type: Article
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The authors propose a new fuzzy logic-based approach for reducing the complexity of the low-delay CELP speech coding algorithm. Subjective listening tests show that the new module for adaptation of the excitation gain gives the same performance as the traditional algorithm. - Author(s): A.K. Khandani
- Source: Electronics Letters, Volume 33, Issue 22, p. 1847 –1849
- DOI: 10.1049/el:19971265
- Type: Article
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The author presents a multidimensional cubic constellation with a non-flat power spectrum. The objective is to maximise the rate for a fixed average energy, subject to certain constraints on the resulting power spectrum. - Author(s): M.P. Fitton ; A.R. Nix ; M.A. Beach
- Source: Electronics Letters, Volume 33, Issue 22, p. 1849 –1850
- DOI: 10.1049/el:19971292
- Type: Article
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Frequency hopping spread spectrum (FH-SS) has found a number of applications in both CDMA and TDMA cellular systems, wireless local loop, and wireless local area networks. Propagation studies and statistical analysis are employed to show that the frequency hopped channel displays improved short-term characteristics when compared to the non-hopped case. Furthermore, novel analyses of the short-term statistics of the frequency-hopped channel enable prediction of the performance of an FH system.
2n modified prime codes for use in fibre optic CDMA networks
Blind MLSE equaliser with fuzzy metric calculation for mobile radio environments
Interactive digital television at 42 GHz
Low complexity correlation receiver for rate variable SQAM modem
Low-complexity fuzzy control of excitation gain in LD-CELP speech coding
Multidimensional cubic constellation with non-flat power spectrum
Prediction of propagation parameters in frequency hopping spread spectrum
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- Author(s): V.A. Bartlett and E. Grass
- Source: Electronics Letters, Volume 33, Issue 22, p. 1850 –1852
- DOI: 10.1049/el:19971272
- Type: Article
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A completion-detection technique is introduced for bundled-data asynchronous systems implemented in single-rail dynamic CMOS logic. Its application to a carry-ripple adder is presented showing significant benefits in terms of performance and area overhead. - Author(s): M. Fleury ; A.C. Downton ; A.F. Clark
- Source: Electronics Letters, Volume 33, Issue 22, p. 1852 –1853
- DOI: 10.1049/el:19971249
- Type: Article
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Four uses of order statistics for modelling parallel pipelines are proposed. The models are relevant to embedded applications using message-passing machines. A novel combination of queueing theory and order statistics, and a way of predicting degradation through any output-sequencing constraint are given. A simulation confirms the robustness of the analytic results.
Completion-detection technique for dynamic logic
Modelling pipelines for embedded parallel processor system design
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- Author(s): J.H. Yun and J.K. Kim
- Source: Electronics Letters, Volume 33, Issue 22, p. 1853 –1854
- DOI: 10.1049/el:19971248
- Type: Article
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A circular TEM (CTEM) cell for achieving the radiated EMC test without any rotation of the equipment under test is proposed. The authors also analyse field uniformity inside the cell and characteristic impedance by using a moment method (MM) which can determine the number of segments per line efficiently. - Author(s): L. Xu ; Z.Q. Zhu ; D.A. Stone ; D. Howe
- Source: Electronics Letters, Volume 33, Issue 22, p. 1855 –1856
- DOI: 10.1049/el:19971245
- Type: Article
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A novel technique, referred to as software waiting loop length control (SWLLC), for reducing the radiated EMI from microprocessor-based PWM drive systems is presented. By randomly changing the length of the software waiting loops, the energy concentrated into discrete bands by the action of periodic signals on the external and internal buses of the microprocessor system can be spread across a larger frequency range. Using this technique, significant reduction of radiated interference levels has been observed in a typical PWM drive system.
Circular TEM cell for generating standard electromagnetic fields
Software waiting loop length control: Technique for reduction of radiated EMI from microprocessor-based PWM drive system
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- Author(s): M.K. Quweider and J.B. Farison
- Source: Electronics Letters, Volume 33, Issue 22, p. 1856 –1857
- DOI: 10.1049/el:19971274
- Type: Article
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The authors present a new image edge block classification method using a set of orthhogonal projection filters, accomplished by choosing the index of the filter that gives the maximum output magnitude. Coded monochromatic images with 0.625 – 0.813 bits/pixel are shown to preserve their quality and edge integrity, as seen by subjective and objective measures. - Author(s): R. Bowden ; T.A. Mitchell ; M. Sarhadi
- Source: Electronics Letters, Volume 33, Issue 22, p. 1858 –1859
- DOI: 10.1049/el:19971300
- Type: Article
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In the field of computer vision, principle component analysis (PCA) is often used to provide statistical models of shape, deformation or appearance. This simple statistical model provides a constrained, compact approach to model based vision. However, as larger problems are considered, high dimensionality and nonlinearity make linear PCA an unsuitable and unreliable approach. A nonlinear PCA (NLPCA) technique is proposed which uses cluster analysis and dimensional reduction to provide a fast, robust solution. Simulation results on both 2D contour models and greyscale images are presented. - Author(s): H.Y. Kim ; F.A.M. Cipparrone ; M.T.C. Andrade
- Source: Electronics Letters, Volume 33, Issue 22, p. 1859 –1861
- DOI: 10.1049/el:19971268
- Type: Article
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A new approach to grey-scale fuzzy mathematical morphology is presented. In this approach, any grey-scale window operator can be constructed using a fuzzy expert system. Many useful operators can be built using a small number of fuzzy rules.
Classification of image edge blocks by orthogonal projection
Cluster based nonlinear principle component analysis
Technique for constructing grey-scale morphological operators using fuzzy expert system
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- Author(s): Wei-HuaHe and Tzong-ChenWu
- Source: Electronics Letters, Volume 33, Issue 22, p. 1861 –1862
- DOI: 10.1049/el:19971243
- Type: Article
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The authors present an improvement to the Nyang-Song scheme which achieves the same security level, without increasing the cost of signature generation, and which offers two significant advantages. - Author(s): S.A.G. Chandler ; F.H. Ali ; P. Thomas
- Source: Electronics Letters, Volume 33, Issue 22, page: 1863 –1863
- DOI: 10.1049/el:19971267
- Type: Article
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The authors show that the linear independence of codewords previously assumed for CV-CCMA to uniquely decode individual transmissions, is not necessary if the number of superimposed codewords is less than the codeword length. It is shown, in fact, that all pairs of two N-tuples of BPSK and QPSK symbols may be simultaneously received by the technique.
Improvement to Nyang-Song fast digital signature scheme
Permissible codewords for CV-CCMA system
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- Author(s): R.Y. Chen
- Source: Electronics Letters, Volume 33, Issue 22, p. 1864 –1865
- DOI: 10.1049/el:19971298
- Type: Article
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p.
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A high-speed CMOS frequency divider is proposed. Using fewer transistors and only NMOS transistors in the regenerative circuits of the latches, the frequency divider achieves higher speed through the reduced capacitances at the output nodes and larger transconductance. A device sizing rule for the maximum input frequency is given. The proposed frequency divider is suitable for high-speed operation, while consuming a moderate amount of power.
High-speed CMOS frequency divider
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- Author(s): K. Okamoto ; T. Hasegawa ; O. Ishida ; A. Himeno ; Y. Ohmori
- Source: Electronics Letters, Volume 33, Issue 22, p. 1865 –1866
- DOI: 10.1049/el:19971246
- Type: Article
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A 32 × 32 arrayed-waveguide grating multiplexer with uniform loss and cyclic frequency characteristics has been fabricated on a silica-based planar lightwave circuit. The device consists of an 80-channel arrayed-waveguide multiplexer with 100 GHz spacing and 32 optical combiners which are connected to the 72 output waveguides of the multiplexer. The peak-to-peak loss and channel centre frequency variations are 1.2 dB and 22.3 GHz, respectively, for entire 32 × 32 input/output combinations. These values have been substantially improved from conventional arrayed-waveguide multiplexers with peak-to-peak loss and centre frequency variations of 4.7 dB and 75.6 GHz, respectively. - Author(s): A. Okada
- Source: Electronics Letters, Volume 33, Issue 22, p. 1866 –1868
- DOI: 10.1049/el:19971270
- Type: Article
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Lamination of a fluorinated polyimide film on a UV-curable resin film for polarisation-controlling device applications is described. Using this technique, a waveguide polariser was fabricated and its performance was evaluated. Extinction ratios of not less than 28 dB and an insertion loss of 0.3 dB were obtained at the measured wavelength of 1.30 µm.
32×32 arrayed-waveguide grating multiplexer with uniform loss and cyclic frequency characteristics
Lamination of a fluorinated polyimide film on a UV-curable resin film for applications in polarisation-controlling waveguide devices
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- Author(s): T. Shimizu ; I. Ogura ; H. Yokoyama
- Source: Electronics Letters, Volume 33, Issue 22, p. 1868 –1869
- DOI: 10.1049/el:19971266
- Type: Article
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The repetition frequency of modelocked laser diodes was increased to 860 GHz. This modelocking frequency was controlled simply by adjusting the position of a single saturable absorber in the asymmetric colliding pulse device geometry. - Author(s): S. O'Brien ; H. Zhao ; A. Schoenfelder ; R.J. Lang
- Source: Electronics Letters, Volume 33, Issue 22, p. 1869 –1871
- DOI: 10.1049/el:19971234
- Type: Article
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Wide aperture lasers have been fabricated which produce a record maximum power of 9.3 W CW at 970 nm. This record power is achieved with (In)AlGaAs-based materials using relatively short cavity lengths and standard mounting onto copper heatsinks. Detailed measurements of the emitted far field pattern in both the fast and slow axes have been made up to 6 W CW power level. - Author(s): L.V. Asryan and R.A. Suris
- Source: Electronics Letters, Volume 33, Issue 22, p. 1871 –1872
- DOI: 10.1049/el:19971286
- Type: Article
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The characteristic temperature of a quantum dot laser, T0, has been calculated for the first time considering carrier recombination in the optical confinement layer and violation of the charge neutrality in QDs. T0 is shown to fall off profoundly with increasing temperature, which is in line with the available experimental results. - Author(s): M. Teshima ; K. Sato ; M. Koga
- Source: Electronics Letters, Volume 33, Issue 22, p. 1872 –1874
- DOI: 10.1049/el:19971283
- Type: Article
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The authors describe a technique for narrowing the linewidth and stabilising the frequencies of individual teeth of an active modelocked laser diode. This is achieved even if the power of the injected tooth is weakly oscillating. Injection locking is demonstrated for a weakly oscillating tooth at 21.7 dB-down from the peak. - Author(s): Y.B. Li ; J.W. Cockburn ; M.S. Skolnick ; M.J. Birkett ; J.P. Duck ; R. Grey ; G. Hill
- Source: Electronics Letters, Volume 33, Issue 22, p. 1874 –1875
- DOI: 10.1049/el:19971209
- Type: Article
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The authors report the first observation of intersubband electroluminescence in GaAs/AlGaAs-based quantum cascade structures. A 100 Å Al0.15Ga0.85As/Al0.4Ga0.6As well is employed to bridge the individual active regions to enhance the overall quantum efficiency, thus greatly simplifying the design and growth of quantum cascade structures. - Author(s): A. Shen ; S. Bouchoule ; P. Crozat ; D. Mathoorasing ; J.-M. Lourtioz ; C. Kazmierski
- Source: Electronics Letters, Volume 33, Issue 22, p. 1875 –1877
- DOI: 10.1049/el:19971281
- Type: Article
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High repetition rate picosecond pulses with low uncorrelated timing jitter (down to ~0.25 ps) have been generated at 1.55 µm from gain- and Q-switched InGaAsP lasers without external feedback. Experiments were carried out at multi-gigahertz frequencies on one- and two-section devices; the timing jitter was estimated from spectral measurements. Sub-picosecond values were found above ~5 GHz for optimally-biased one-section DFB lasers in gain-switching. Values more than two times lower were obtained from Q-switched quantum well two-section lasers, with RF modulation applied to a fast absorber section. - Author(s): A. Mizutani ; N. Hatori ; N. Nishiyama ; F. Koyama ; K. Iga
- Source: Electronics Letters, Volume 33, Issue 22, p. 1877 –1878
- DOI: 10.1049/el:19971285
- Type: Article
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The authors have realised an InGaAs/GaAs vertical cavity surface emitting laser grown on a GaAs (311)B substrate by metal-organic chemical-vapour deposition. A carbon auto-doping technique was used to avoid the difficulty of p-type doping (>1019 cm–3) AlAs for a distributed Bragg reflector. A low electrical resistance of p-type GaAs/AlAs DBRs on GaAs (311)B was obtained by using delta doping and compositional grading layers. The lowest threshold was 16 mA at room temperature CW operation for a 50 µm diameter device. The threshold current density is 810 A/cm2 which is reasonably low for non-optimised experimental conditions. The polarisation state was stable. - Author(s): O. Blum ; J.F. Klem ; K.L. Lear ; G.A. Vawter ; S.R. Kurtz
- Source: Electronics Letters, Volume 33, Issue 22, p. 1878 –1880
- DOI: 10.1049/el:19971284
- Type: Article
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The authors demonstrate, for the first time, 77 K CW operation of an optically pumped, monolithic, all-epitaxial vertical cavity laser, emitting at 1.56 µm. The laser incorporates 15 and 20 period Al0.12Ga0.88As0.56Sb0.44/AlAs0.56Sb0.44 distributed Bragg reflectors for the top and bottom mirrors, respectively. The entire structure was grown in a single growth run by molecular beam epitaxy. - Author(s): Y.F. Chen ; T.M. Huang ; C.L. Wang
- Source: Electronics Letters, Volume 33, Issue 22, p. 1880 –1881
- DOI: 10.1049/el:19971303
- Type: Article
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A compact diode-pumped passively Q-switched laser has been demonstrated with a coated Cr4+:YAG crystal as both a saturable absorber and an output coupler. When CW pumped with a fibre-coupled laser diode, the laser produces pulses of 5–30 ns duration, with a repetition rate of 75–90 kHz. The highest peak power was 430 W, obtained at 1.6 W of pump power, which is a 520 times enhancement in comparison to an output power of 830 mW under CW operation. - Author(s): A. Talneau ; J. Charil ; A. Ougazzaden
- Source: Electronics Letters, Volume 33, Issue 22, p. 1881 –1883
- DOI: 10.1049/el:19971301
- Type: Article
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The authors demonstrate extremely low threshold and high CW output power in 1.55 µm gain coupled DFB lasers. The structure is an MQW strain compensated active layer with first-order grating etched on the upper wells. The lowest thresholds of 2.5 mA at 20°C and 10 mA at 80°C are obtained using one HR facet coating. With an AR front facet, the CW output is increased up to 40 mW, while the threshold current remains < 10 mA.
860 GHz rate asymmetric colliding pulse modelocked diode lasers
9.3 W CW (In)AlGaAs 100 µm wide lasers at 970 nm
Characteristic temperature of quantum dot laser
Injection locking a weakly oscillating tooth of active modelocked laser diode
Intersubband electroluminescence in GaAs/AlGaAs quantum cascade structures
Low timing jitter of gain- and Q-switched laser diodes for high bit rate OTDM applications
MOCVD grown InGaAs/GaAs vertical cavity surface emitting laser on GaAs (311)B substrate
Optically pumped, monolithic, all-epitaxial 1.56 µm vertical cavity surface emitting laser using Sb-based reflectors
Passively Q-switched diode-pumped Nd: YVO4/Cr4+:YAG single-frequency microchip laser
Very low threshold and high power CW operation in 1.55 µm gain-coupled DFB lasers with periodically etched quantum wells
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- Author(s): C. Shearwood and R.B. Yates
- Source: Electronics Letters, Volume 33, Issue 22, p. 1883 –1884
- DOI: 10.1049/el:19971262
- Type: Article
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An electromagnetic micro-generator is described, based on a planar pick-up coil and flexible polyimide membrane of diameter 2 mm with attached magnet. During large amplitudes of vibration of the device, the membrane displacement characteristics become nonlinear due to the spring stiffening effect, limiting the maximum generated power to 0.3 µW.
Development of an electromagnetic micro-generator
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- Author(s): R.-P. Braun ; G. Grosskopf ; R. Meschenmoser ; D. Rohde ; F. Schmidt ; G. Villino
- Source: Electronics Letters, Volume 33, Issue 22, p. 1884 –1886
- DOI: 10.1049/el:19971288
- Type: Article
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Two low phase noise microwave signals in the 18–20 GHz band have been remotely generated for bidirectional 140 Mbit/s OQPSK-transmissions by applying a simple optical harmonic upconversion technique. One carrier is modulated by the downlink data and the other one serves as local oscillator signal for the uplink mixer in the base station.
Optical harmonic upconversion for microwave generation in bidirectional broadband mobile communication system
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- Author(s): Jung-WookCho and Soo-YoungLee
- Source: Electronics Letters, Volume 33, Issue 22, p. 1886 –1887
- DOI: 10.1049/el:19971277
- Type: Article
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1886
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Modular neuro-chip sets with an on-chip learning capability are applied to adaptive nonlinear equalisers for mobile communication receivers. Using a multilayer perceptron with a decision feedback architecture is successful for equalising not only minimum phase channels but also nonminimum phase channels.
Analogue neuro-chip with on-chip learning capability for adaptive nonlinear equalisers
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- Author(s): A. Bononi ; L.A. Rusch ; L. Tancevski
- Source: Electronics Letters, Volume 33, Issue 22, p. 1887 –1888
- DOI: 10.1049/el:19971273
- Type: Article
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1887
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Building on the results in , the authors have determined that the gain dynamics of a doped-fibre amplifier are completely specified by its total number of excited ions whose time behaviour is described by a simple first-order differential equation. An equivalent electrical circuit is derived, so that any circuit analysis package can be used to solve for complex networks of optical fibre amplifiers. - Author(s): B.H. Wang ; C.C. Hsiao ; W.I. Way
- Source: Electronics Letters, Volume 33, Issue 22, p. 1888 –1890
- DOI: 10.1049/el:19971275
- Type: Article
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1888
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The authors propose adding a coherent in-band clipping carrier to a previously demonstrated Walsh-code-based synchronised CDMA (S-CDMA) technique to further suppress the optical beat interference (OBI). Experimental results showed that a negligible system power penalty can be achieved even when the OBI-induced intensity noise was as high as –90.9 dB/Hz. In addition, a large system dynamic range of 10 dB can be obtained to relax the tight power control requirement on S-CDMA signals. - Author(s): T. Kurokawa ; H. Tsuda ; K. Okamoto ; K. Naganuma ; H. Takenouchi ; Y. Inoue ; M. Ishii
- Source: Electronics Letters, Volume 33, Issue 22, p. 1890 –1891
- DOI: 10.1049/el:19971258
- Type: Article
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1890
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The authors propose time-space-conversion optical signal processing using an arrayed-waveguide grating. It provides a wide time window, compatibility with fibre optics, compactness, and integration capabilities. Pulse train generation is demonstrated to confirm its performance at the wavelength of 1.55 µm.
Simple dynamic model of fibre amplifiers and equivalent electrical circuit
Suppression of optical beat interference using synchronised CDMA technique and in-band clipping carrier
Time-space-conversion optical signal processing using arrayed-waveguide grating
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- Author(s): M. Durkin ; M. Ibsen ; M.J. Cole ; R.I. Laming
- Source: Electronics Letters, Volume 33, Issue 22, p. 1891 –1893
- DOI: 10.1049/el:19971291
- Type: Article
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1891
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The authors present the realisation of high-quality 1 m long continuously-written fibre Bragg gratings designed to compensate both second- and third-order fibre dispersion. These compact devices are ideal for counteracting the effects of fibre dispersion in high bit rate transmission systems. - Author(s): M.G. Xu ; R. Maaskant ; M.M. Ohn ; A.T. Alavie
- Source: Electronics Letters, Volume 33, Issue 22, p. 1893 –1894
- DOI: 10.1049/el:19971244
- Type: Article
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p.
1893
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Independent tuning of cascaded long period fibre gratings (LPFGs) is demonstrated. This involves applying a small controllable bend to each LPFBG, resulting in a synthetic spectral response due to the spectral overlap. This technique provides high spectral shaping flexibility coupled with high sensitivity and a wide tuning range. - Author(s): J.-P. Elbers ; C. Glingener ; M. Düser ; E. Voges
- Source: Electronics Letters, Volume 33, Issue 22, p. 1894 –1895
- DOI: 10.1049/el:19971297
- Type: Article
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p.
1894
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Polarisation mode dispersion is commonly simulated by using a birefringent waveplate model. In contrast to several publications which assume a Maxwell probability density function, we found that the differential group delay is, to a good approximation, Rayleigh distributed. - Author(s): J.J. Pan and Y. Shi
- Source: Electronics Letters, Volume 33, Issue 22, p. 1895 –1896
- DOI: 10.1049/el:19971264
- Type: Article
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p.
1895
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Dense WDM systems demand fibre Bragg gratings (FBG) with low sidelobes and a sharp spectral skirt. A new apodised phase mask is reported here for efficiently suppressing sidelobes in FBG production. A 20 dB sidelobe reduction, measured by both an OSA and a tunable laser scanning technique, was achieved. The skirt steepness, which is a ratio of the FBG reflection bandwidth at –25 dB to the bandwidth at –0.5 dB, was demonstrated to be 1.85. The FBGs are suitable for dense WDM with a channel spacing of < 0.8 nm.
1 m long continuously-written fibre Bragg gratings for combined second- and third-order dispersion compensation
Independent tuning of cascaded long period fibre gratings for spectral shaping
Modelling of polarisation mode dispersion in singlemode fibres
Steep skirt fibre Bragg grating fabrication using a new apodised phase mask
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- Author(s): L. Dong ; L. Reekie ; J.L. Cruz
- Source: Electronics Letters, Volume 33, Issue 22, p. 1897 –1898
- DOI: 10.1049/el:19971247
- Type: Article
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p.
1897
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In a singlemode fibre of a depressed cladding design, the LP11 mode is leaky but can propagate over a short length of fibre. This leaky LP11 mode can be used instead of the conventional cladding modes in long period gratings, with two extra benefits: a larger overlap, giving stronger coupling, and coupling which is insensitive to the glass-air interface, therefore packaging is easier.
Long period gratings formed in depressed cladding fibres
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- Author(s): G.A. Fish ; L.A. Coldren ; S.P. DenBaars
- Source: Electronics Letters, Volume 33, Issue 22, p. 1898 –1900
- DOI: 10.1049/el:19971242
- Type: Article
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p.
1898
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A novel, compact optical switch designed for use with integrated amplifiers to create more scalable photonic crossconnects is reported. The basic operation of the switch is described and experimentally verified. On/off ratios of 16.2 dB (7.5 dB) in the bar (cross) state are demonstrated with currents < 30 mA and a very low bar state excess loss of 0.5 dB.
Compact InGaAsP/InP 1×2 optical switch based on carrier induced supression of modal interference
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- Author(s): T. Le-Tien and D.T. Nguyen
- Source: Electronics Letters, Volume 33, Issue 22, p. 1900 –1901
- DOI: 10.1049/el:19971296
- Type: Article
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p.
1900
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The behaviour of scattering mechanisms in the time-scale domain against random noise is presented for stepped frequency radar. The down range profile is obtained from the continuous wavelet transform (CWT) of the backscattered data. Local maxima detected corresponding to different noise levels confirm the invariant location and number of scattering centres in the range profile. They provide crucial information for automatic target recognition.
Performance of behaviour of scattering mechanisms in time-scale domain against random noise for centimetre wave radar
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- Author(s): E. Vilar and S. Senin
- Source: Electronics Letters, Volume 33, Issue 22, p. 1901 –1902
- DOI: 10.1049/el:19971251
- Type: Article
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p.
1901
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Experimental evidence of the existence of propagation phase noise or phase scintillations is reported using a one-way only radio link. The noise has been found to exceed on occasions the downlink 40 GHz beacon phase noise of Italsat in what appear to be conditions of cumulus clouds and high turbulence. Experimental and theoretical values are given for the power spectral density and reference is made to past work and immediate applications to systems.
Propagation phase noise identified using 40 GHz satellite downlink
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- Author(s): J. Frounchi and S. Harrold
- Source: Electronics Letters, Volume 33, Issue 22, p. 1902 –1904
- DOI: 10.1049/el:19971278
- Type: Article
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p.
1902
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A new method for eliminating the sensitivity of the output current of a current source to the threshold voltage is introduced. The application of this technique is examined in a GaAs D-HEMT current source. This technique can be applied to any FET technology. - Author(s): K. Tone ; S.R. Weiner ; J.H. Zhao
- Source: Electronics Letters, Volume 33, Issue 22, p. 1904 –1906
- DOI: 10.1049/el:19971254
- Type: Article
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p.
1904
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N-type 6H-SiC wafers have been implanted with C and Al, or Al only, at room temperature or 600°C for a comparative study with the emphasis on determining the dependence of the sheet resistivity and specific contact resistance of Al ohmic contacts on the concentration of implanted Al. The optimum implantation concentration is reported for the first time, along with clear evidence showing the advantage of C-Al co-implantation over Al single implantation. - Author(s): ZhiChen and S. Noor Mohammad
- Source: Electronics Letters, Volume 33, Issue 22, p. 1906 –1907
- DOI: 10.1049/el:19971276
- Type: Article
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p.
1906
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A high quality Si3N4/Si/p-GaAs MIS structure has been obtained by the ex-situ growth approach. An interface trap density as low as 9 × 1010 eV–1cm–2 was obtained from the conductance measurements. A depletion-mode MISFET with a transconductance of 85 mS/mm has been fabricated using this ex-situ growth approach. - Author(s): T. Ouisse ; E. Platel ; T. Billon ; H. Lahreche
- Source: Electronics Letters, Volume 33, Issue 22, p. 1907 –1909
- DOI: 10.1049/el:19971302
- Type: Article
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p.
1907
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Discrete time switching events are observed when measuring the current of silicon carbide Schottky diodes. RTS noise occurs whenever an excess current is measured. The random telegraph signal (RTS) is shown to originate from localised defective areas, whose conductivity may be modulated by the single trapping/detrapping of an electron in the depletion layer, in the neighbourhood of the localised current path. - Author(s): Jong-LamLee ; Hyung MoYoo ; Gi YoungLee
- Source: Electronics Letters, Volume 33, Issue 22, p. 1909 –1910
- DOI: 10.1049/el:19971271
- Type: Article
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p.
1909
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A low current dissipation pseudomorphic high electron mobility transistor with a single-planar-doped AlGaAs/InGaAs/GaAs heterojunction structure, operating at a 3.3 V single voltage supply, has been developed with a state-of-the-art performance. It exhibits a low operating current of 87.8 mA at an output power of 21.8 dBm with high power-added efficiency of 51.5% at a single voltage supply condition. This operating current value is the lowest among those reported for single voltage operation power devices for portable power applications.
Adaptive threshold voltage insensitive FET current source
Carbon and aluminium co-implantation for p-type doping in 6H-SiC
GaAs metal-insulator-semiconductor structure and field effect transistors grown by ex-situ approach
Observation of random telegraph signal in SiC Schottky diodes
Single-voltage-operation pseudomorphic HEMT with low current dissipation for portable power applications
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- Author(s): H.C. So
- Source: Electronics Letters, Volume 33, Issue 22, p. 1910 –1912
- DOI: 10.1049/el:19971295
- Type: Article
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p.
1910
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A simple method is presented for the adaptive cancelling of a sine wave signal of known frequency in a time series. The system is characterised by the phase and amplitude parameters which are updated directly according to an LMS-style algorithm. The convergence behaviours and variances of these parameters are analysed. It is demonstrated that the proposed method can effectively remove the 50 Hz power line interference in the recording of electrocardiograms (ECG).
Adaptive algorithm for sinusoidal interference cancellation
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