Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 25, Issue 15, 20 July 1989
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Volume 25, Issue 15
20 July 1989
Simulation model of sequential multichannel network and its throughput determination
- Author(s): R.L. Brewster and A.M. Glass
- Source: Electronics Letters, Volume 25, Issue 15, p. 941 –942
- DOI: 10.1049/el:19890630
- Type: Article
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A sequential multichannel system has been simulated, based on resolving the allocation of channels in turn to the offered load packets using the CSMA/CA protocol for medium access. A set of throughput curves with different maxima have been obtained for different numbers of subchannels. The relatively low throughput of such a system is compensated for by other desirable features that have been included in the system especially for applications involving radio and mobile radio channels.
Bearing estimation of coherent sources by spatial modulating and in-place reversal averaging technique
- Author(s): B.L. Lim
- Source: Electronics Letters, Volume 25, Issue 15, p. 942 –944
- DOI: 10.1049/el:19890631
- Type: Article
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A novel spatial smoothing technique which does not reduce the effective aperture of an array is analysed. Its capability to resolve incident sources in various coherent signal environments is preserved, as compared with the conventional spatial smoothing technique and the modified spatial smoothing algorithm.
Wavelength dependence of 3×3 fibre couplers for gyro applications
- Author(s): G. Trommer
- Source: Electronics Letters, Volume 25, Issue 15, p. 944 –945
- DOI: 10.1049/el:19890632
- Type: Article
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The wavelength dependence of the scattering matrix of a 3×3 fibre coupler for gyroscope applications is investigated. A new method, using only simple intensity measurements is developed, yielding the amplitudes as well as the phases of the scattering matrix including the wavelength dependence of the three coupling lengths. Excellent symmetry properties of the investigated 3×3 coupler have been found.
Low-loss planar optical polarisation splitter with small dimensions
- Author(s): A.R. Vellekoop and M.K. Smit
- Source: Electronics Letters, Volume 25, Issue 15, p. 946 –947
- DOI: 10.1049/el:19890633
- Type: Article
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A novel planar polarisation splitter with the smallest dimensions thus far reported (0.6 × 2.5 mm2) is presented. The component, which is based on an optical phased array, was designed and fabricated using conventional (high-quality) optical lithography. Insertion losses as low as 0.5 dB and crosstalk values of 17–21 dB have been achieved.
Losses in small-radius bends in single-mode fibres
- Author(s): N. Kamikawa and C.-T. Chang
- Source: Electronics Letters, Volume 25, Issue 15, p. 947 –949
- DOI: 10.1049/el:19890634
- Type: Article
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Refractive index profiles and mode field radii determine small-radius bending losses in single-mode fibres. Losses in six different types of fibres were measured in bends with radii ranging from 1.25 to 8 mm. The results show that a refractive index depression in the core centre reduces the bending-loss sensitivity.
Andrew's t-EC/AUED Codes
- Author(s): Y. Saitoh and H. Imai
- Source: Electronics Letters, Volume 25, Issue 15, p. 949 –950
- DOI: 10.1049/el:19890635
- Type: Article
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A new method to construct Andew's t-EC/AUED codes is presented. Codes constructed by this method are more efficient than known codes with equivalent properties.
Modified CORDIC algorithm with reduced iterations
- Author(s): D. Timmermann ; H. Hahn ; B. Hosticka
- Source: Electronics Letters, Volume 25, Issue 15, p. 950 –951
- DOI: 10.1049/el:19890636
- Type: Article
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In this contribution we present a modified CORDIC algorithm that offers a considerable latency time reduction and chip area savings when compared with the original CORDIC method. The operations used are adds, shifts, and multiplication or division.
New RLL code for digital data storage
- Author(s): M. Simić and R. Petrović
- Source: Electronics Letters, Volume 25, Issue 15, p. 951 –953
- DOI: 10.1049/el:19890637
- Type: Article
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A simple, high-efficiency, runlength-limited code for digital optical or magnetic recording is presented. The parameters of the code are R = 1/3 and (d, k) = (5, 16). On the basis of that, this code gains a higher density ratio than any other used code. A state transition diagram for a set of channel constraints and diagrams for the encoder and decoder are presented.
Experimental observation of spectral tuning in twin-segment double quantum well (DQW) AlGaAs diode laser
- Author(s): I.H.. White ; J.J.S. Watts ; B. Garrett
- Source: Electronics Letters, Volume 25, Issue 15, p. 953 –954
- DOI: 10.1049/el:19890638
- Type: Article
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Wavelength tuning of the spectral gain peak in an asymmetric twin segment DQW AlGaAs laser over 6 nm has been achieved by varying a revem bias current to the shorter segment with high forward injection in the longer section. Tuning is attributed to bandgap narrowing at high charge concentrations, allowing the optical wavelength to hop across 70 consecutive modes.
GaInAsP/InP mass transport laser monolithically integrated with photodetector using reactive ion etching
- Author(s): T. Matsui ; H. Sugimoto ; K. Ohtsuka ; Y. Abe ; H. Ogata
- Source: Electronics Letters, Volume 25, Issue 15, p. 954 –956
- DOI: 10.1049/el:19890639
- Type: Article
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A l.5 μm GaInAsP/InP laser is monolithically integrated with a photodiode. The laser is isolated from the photodiode by an etched groove formed by reactive ion etching. Ethane and hydrogen gases are used as an etchant of reactive ion etching instead of chlorinated gas. The threshold current of the laser under CW operation and the sensitivity of the monitor photodiode are 57 mA and 0.24 A/W, respectively.
900 MHz multipath propagation measurements in four United States cities
- Author(s): T.S. Rappaport and S.Y. Seidel
- Source: Electronics Letters, Volume 25, Issue 15, p. 956 –958
- DOI: 10.1049/el:19890640
- Type: Article
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This letter describes multipath power delay profile measurements of 900 MHz mobile radio channels in four US cities. Preliminary data show that for over 98% of the measured locations, RMS delay spreads are less than 12 μs. In very rare instances, reflections from city skylines and mountains can cause RMS delay spreads which exceed 20 μs and excess delays which exceed 100 μs. Such large excess delays have not been previously reported in the literature.
Surface-acoustic-wave unidirectional transducers using anodic oxidation technology and low-loss filters
- Author(s): K. Yamanouchi ; T. Meguro ; K. Matsumoto
- Source: Electronics Letters, Volume 25, Issue 15, p. 958 –960
- DOI: 10.1049/el:19890641
- Type: Article
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A new surface-acoustic-wave interdigital transducer (IDT) and unidirectional transducer (UDT) are described. Using a lift-off anodic oxidation method, controllable gaps between electrodes with good insulation can be obtained. Experimental results show good characteristics at 2nd-harmonic operation for a new floating electrode type unidirectional transducer (NG-FEUDT). Also, a low-loss filter of 3.46dB with side-lobe suppression of 40dB at 893 MHz is obtained using the above techniques.
Frame synchronisation with errors and erasures
- Author(s): P.F. Driessen
- Source: Electronics Letters, Volume 25, Issue 15, p. 960 –961
- DOI: 10.1049/el:19890642
- Type: Article
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The probability of successful frame synchronisation in the presence of jamming or interference may be increased by using bit erasure information without also increasing the total probability of simulated alignment Pt,sim in an incorrect position in the overlap region. An expression for Pt,sim is obtained as a function of the bit error and erasure probability, the specified frame alignment pattern, the amount of overlap and the number of bit errors and erasures which are tolerated in the frame sync word.
Pipelined logical convolvers for binary picture processing
- Author(s): A.D. Hall
- Source: Electronics Letters, Volume 25, Issue 15, p. 961 –963
- DOI: 10.1049/el:19890643
- Type: Article
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Pipelined logical convolvers (PLCs) are well suited to document facsimile processing as they can simply be inserted into the video data stream of scanners, etc. Their introduction has no effect on throughput and they require only a partial picture memory. A method is described for designing and implementing PLCs, using a structured approach that encourages experimentation and produces a cost efficient circuit. An example PLC is presented which performs image smoothing.
Fast measuring frequency-to-voltage convertor with DC output
- Author(s): C.A. Karybakas and T.L. Laopoulos
- Source: Electronics Letters, Volume 25, Issue 15, p. 963 –964
- DOI: 10.1049/el:19890644
- Type: Article
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A new frequency-to-voltage conversion scheme is presented, which offers fast dynamic response and nominally zero output ripple, even when operating with low-frequency inputs. Circuit simplicity and overall performance make this convenor highly suitable for low-frequency applications in instrumentation, measurement and control systems.
High-speed switching characteristics of integrated 4×4 InP optical switch array
- Author(s): Y. Takahashi ; H. Inoue ; T. Kato ; E. Amada
- Source: Electronics Letters, Volume 25, Issue 15, p. 964 –965
- DOI: 10.1049/el:19890645
- Type: Article
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High-speed switching of an InP optical switch array is achieved. Optical switch rise and fall times of 2.8 and 2.5 ns, respectively, are obtained. It is shown that the optical switch module can be utilised in our new ATM switch system.
Frequency-locked loop circuit providing large pull-in range
- Author(s): B. Glance and R.W. Wilson
- Source: Electronics Letters, Volume 25, Issue 15, p. 965 –967
- DOI: 10.1049/el:19890646
- Type: Article
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The letter presents a frequency-locking circuit that provides a larger pull-in bandwidth than that of a conventional automatic frequency control (AFC) circuit. In addition, the proposed circuit has a stable mode of operation over the full frequency response of the frequency discriminator, and locks the oscillator at exactly the centre frequency of this discriminator. The frequency offset and the unstable mode of operation presented by the conventional circuit outside its pull-in range can thus be eliminated.
Planar-junction, top-illuminated GainAs/InP pin photodiode with bandwidth of 25 GHz
- Author(s): D. Wake ; R.H. Walling ; I.D. Henning ; D.G. Parker
- Source: Electronics Letters, Volume 25, Issue 15, p. 967 –969
- DOI: 10.1049/el:19890647
- Type: Article
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967
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A top-illuminated GaInAs/InP pin photodiode has been produced in a planar-junction configuration, which combines high reliability (no change in dark current over 4700 h at 175°C) with the widest bandwidth (25 GHz), and highest quantum efficiency (80% at 1.55 μm), yet reported for this type of device.
Multipurpose single-mode fibre-optic coupling substrate, made with silicon etch and polish technique
- Author(s): P.J. Severin
- Source: Electronics Letters, Volume 25, Issue 15, p. 969 –970
- DOI: 10.1049/el:19890648
- Type: Article
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Using the silicon etch and polish technique a single-mode fibre is exposed uniformly over up to 13 mm length for evanescent mode coupling. This fibre interaction substrate forms the building block for a wide range of fibre-optic devices proposed here. The performance is illustrated experimentally with the coupler as a basic device.
Effects of annealing on electrical properties of Se-implanted GaAs
- Author(s): A.C.T. Tang ; B.J. Sealy ; A.A. Rezazadeh
- Source: Electronics Letters, Volume 25, Issue 15, p. 970 –972
- DOI: 10.1049/el:19890649
- Type: Article
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In this work, we have observed for the first time reversible changes in the sheet carrier concentration of rapid thermally annealed Se-implanted GaAs samples during subsequent heat treatments. The electrical profiles of the Se-implanted samples have also been modified during the annealing processes. These modifications can lead to significant degradation in the performance of devices.
10 watt CW, 5000 h lifetime monolithic AlGaAs laser diode arrays
- Author(s): M. Sakamoto ; D.F. Welch ; J.G. Endriz ; E.P. Zucker ; D.R. Scifres
- Source: Electronics Letters, Volume 25, Issue 15, p. 972 –973
- DOI: 10.1049/el:19890650
- Type: Article
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1 cm-wide monolithic laser diode arrays emitting at about 810 nm with a 3 mm total active aperture width have been life-tested at 10 W constant power at 20°C heat-sink temperature. One array has been operated for over 3000 h and has a projected lifetime in excess of 5000 h.
Intensity modulation at 1.06μm wavelength using ultranarrow GaInAsP quantum wells
- Author(s): J.E. Zucker ; I. Bar-Joseph ; C.H. Joyner ; A. Dentai ; M.D. Divino ; D.S. Chemla
- Source: Electronics Letters, Volume 25, Issue 15, p. 973 –975
- DOI: 10.1049/el:19890651
- Type: Article
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We demonstrate large electroabsorption at 1.06μm associated with field-induced tunnelling in ultranarrow GaInAsP quantum wells.
Threshold voltage of submicron Ga0.47In0.53As HIGFETs
- Author(s): M.D. Feuer ; S.C. Shunk ; J.M. Kuo ; D.M. Tennant ; B. Tell
- Source: Electronics Letters, Volume 25, Issue 15, p. 975 –976
- DOI: 10.1049/el:19890652
- Type: Article
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We present threshold voltage data for Al0.48In0.52As/Ga0.47In0.53As/InP heterostructure insulated gate FETs (HIGFETs) with gate lengths from 1.2μm to 0.4μm. The refractory-gate, self-aligned fabrication process was applied to MBE-grown structures with 300Å Ga0.47In0.53As channels and semi-insulating superlattice buffers, to achieve sharp pinchoff with excellent threshold uniformity. HIGFETs with L = l.2μm showed a threshold voltage of −0.076 ± 0.019V, making them well-suited to application in direct-coupled FET logic (DCFL) circuits.
External feedback effects on I/L characteristics of laser diode
- Author(s): E.G. Vicente de Vera and E. Bernabéu
- Source: Electronics Letters, Volume 25, Issue 15, p. 976 –978
- DOI: 10.1049/el:19890653
- Type: Article
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A new effect of an external cavity on the optical power against injected current curve of an AlGaAs laser diode is reported. A simple multimode rate equation model describes this feature and leads to a novel method of measuring the current-dependent frequency deviation in the low-frequency region, without using spectroscopic instrumentation.
Electron pulse generation at 64 GHz in scanning electron microscope
- Author(s): J.T.L. Thong ; B.C. Breton ; W.C. Nixon
- Source: Electronics Letters, Volume 25, Issue 15, p. 978 –979
- DOI: 10.1049/el:19890654
- Type: Article
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An electron beam chopping technique has been developed which enables the generation of electron pulses at tens of GHz in an SEM. This is effected by deflecting the beam in a circle and chopping it with a multislot aperture. Electron pulses have been produced at 64 GHz and measured, and a waveform measurement at 18 GHz demonstrates its potential application to electron beam characterisation of very high speed devices and MMICS.
2.5 W, C-band, GaAs/AlGaAs heterojunction bipolar power transistor
- Author(s): A.P. Long ; I.H. Goodridge ; J.P. King ; A.J. Holden ; J.G. Metcalfe ; R.C. Hayes ; R. Nicklin ; R.C. Goodfellow
- Source: Electronics Letters, Volume 25, Issue 15, p. 979 –981
- DOI: 10.1049/el:19890655
- Type: Article
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A high-power GaAs/AlGaAs microwave heterojunction bipolar transistor (HBT) with a total emitter periphery of 1.2mm has been designed and fabricated. At 4 GHz an output power at idB gain compression of 1W with 5dB gain and 30% peak power added efficiency was obtained in CW class A. Under pulse bias operation the output power increased to 2.54 W with 6.4 dB gain and 37% peak power added efficiency. This represents a significant increase in power handling over previous power HBTs and demonstrates the potential of these devices as building blocks in power amplifier modules. A large-signal model has been developed to run on SPICE to predict the power performance for the device and the optimum load impedances.
Integrated optic 1×4 splitter in SiO2/GeO2
- Author(s): N. Nourshargh ; E.M. Starr ; T.M. Ong
- Source: Electronics Letters, Volume 25, Issue 15, p. 981 –982
- DOI: 10.1049/el:19890656
- Type: Article
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We report for the first time the fabrication of a single-mode germania-doped silica 1×4 splitter using microwave plasma CVD and reactive ion etching. The device is fabricated on a silica substrate, has a splitting ratio of 6 ± l.4 dB and a total excess loss (including fibre coupling) of 3.1 dB, at 1.3 μm.
Alternative implementation of systolic recursive digital filters
- Author(s): M. Kaneko
- Source: Electronics Letters, Volume 25, Issue 15, p. 982 –983
- DOI: 10.1049/el:19890657
- Type: Article
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A new systolic array for the implementation of a recursive digital filter is presented. The operation-delay macrocomponent and the unit delay are the only elements composing the filter architecture. This architecture is fully pipelined and the output can be taken every cycle.
Low-voltage multiple quantum well reflection modulator with on:off ratio > 100:1
- Author(s): M. Whitehead ; A. Rivers ; G. Parry ; J.S. Roberts ; C. Button
- Source: Electronics Letters, Volume 25, Issue 15, p. 984 –985
- DOI: 10.1049/el:19890658
- Type: Article
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We report the demonstration of a high-contrast (> 100:1), low-voltage multiple quantum well reflection modulator. The performance is achieved by using resonantly-enhanced electroabsorption in GaAs quantum wells embedded in the spacer region of an asymmetric Fabry-Pérot cavity, which is at the same time a pin diode. Optimum contrast is observed at ≃860nm with only 9 V bias and ≈3.5dB insertion loss.
Ion-implanted Nd:YAG planar waveguide laser
- Author(s): P.J. Chadler ; S.J. Field ; D.C. Hanna ; D.P. Shepherd ; P.D. Townsend ; A.C. Tropper ; L. Zhang
- Source: Electronics Letters, Volume 25, Issue 15, p. 985 –986
- DOI: 10.1049/el:19890659
- Type: Article
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We report the first operation of an ion-implanted dielectric waveguide laser. Details of the Nd: YAG waveguide structure, spectroscopic properties, and laser performance are given.
Twin-ridge laser amplifier crosspoint switch
- Author(s): D.A.H. Mace ; M.J. Adams ; J. Singh ; M.A. Fisher ; L.D. Henning ; W.J. Duncan
- Source: Electronics Letters, Volume 25, Issue 15, p. 987 –988
- DOI: 10.1049/el:19890660
- Type: Article
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987
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We report the first demonstration of a crosspoint switch with gain using a twin-ridge laser amplifier. Crossover behaviour is controlled either electrically by varying the injection currents into the ridges, or optically, by adjusting the intensity of the input signal.
Very narrow spectral linewidth of GaInAs MQW-DFB-PPIBH laser diodes
- Author(s): Y. Sakakibara ; A. Takemoto ; Y. Nakajima ; M. Fujiwara ; N. Yoshida ; S. Kakimoto
- Source: Electronics Letters, Volume 25, Issue 15, p. 988 –990
- DOI: 10.1049/el:19890661
- Type: Article
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Five-well GaInAs MQW-DFB-PPIBH laser diodes have been fabricated. The low threshold current of 19 mA and the very narrow spectral linewidth of 1.1 MHz have been achieved in the 300 μm solitary lasers.
Tunable, narrow-linewidth and high-power λ/4-shifted DFB laser
- Author(s): Y. Kotaki ; S. Ogita ; M. Matsuda ; Y. Kuwahara ; H. Ishikawa
- Source: Electronics Letters, Volume 25, Issue 15, p. 990 –992
- DOI: 10.1049/el:19890662
- Type: Article
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A 1.5μm-range λ/4-shifted DFB laser with a l.2 mm-longcavity and three electrodes has been fabricated. The lasing wavelength can be tuned electrically over a 1.9 nm range, maintaining the linewidth below 900 kHz and a constant output power of 20 mW. The minimum linewidth of 500 kHz is achieved by nonuniform current injection.
One-dimensional ballistic resistor in hot-electron regime: nonlinear and negative differential resistance to 10 THz
- Author(s): M.J. Kelly ; R.J. Brown ; C.G. Smith ; D.A. Wharam ; M. Pepper ; H. Ahmed ; D.G. Hasko ; D.C. Peacock ; J.E.F. Frost ; R. Newbury ; D.A. Ritchie ; G.A.C. Jones
- Source: Electronics Letters, Volume 25, Issue 15, p. 992 –993
- DOI: 10.1049/el:19890663
- Type: Article
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We extend into the high field regime the usual (very low field) treatment of the one-dimensional (ID) ballistic resistor that leads to quantised resistance. We find nonlinear resistance and eventually negative differential resistance (NDR) with a high-frequency cutoff above 10 THz. We outline preliminary experimental evidence in support.
AlGaAs/GaInAs strained-base pnp heterojunction bipolar transistors
- Author(s): D.G. Hill ; W.S. Lee ; T. Ma ; J.S. Harris
- Source: Electronics Letters, Volume 25, Issue 15, p. 993 –994
- DOI: 10.1049/el:19890664
- Type: Article
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We report the first strained-layer pnp heterojunction bipolar transistors fabricated in the AlGaAs/GaInAs/GaAs system. Despite significant lattice mismatch between the Ga0.9In0.1As base layer and AlGaAs emitter, the current gain was comparable to that of similar AlGaAs/GaAs transistors. A maximum gain of 35 was observed for a device with graded In content across the base.
GaAs/AlGaAs multiple quantum well optical modulator using multilayer reflector stack grown on Si substrate
- Author(s): P. Barnes ; P. Zouganeli ; A. Rivers ; M. Whitehead ; G. Parry ; K. Woodbridge ; C. Roberts
- Source: Electronics Letters, Volume 25, Issue 15, p. 995 –996
- DOI: 10.1049/el:19890665
- Type: Article
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We report the first pin multiple quantum well reflection modulator grown on Si with a quarter-wave stack dielectric mirror. The structures demonstrated were grown by MBE, with a 75 period MQW, and achieved a relative change in reflectivity of 31% with 8 V applied bias at 865 nm. The absolute change in reflectivity was 17%.
Polarisation diversity optical receiver using novel combining method
- Author(s): H. Tsushima ; S. Sasaki ; S. Kitajima ; K. Yamashita
- Source: Electronics Letters, Volume 25, Issue 15, p. 996 –998
- DOI: 10.1049/el:19890666
- Type: Article
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A polarisation diversity optical receiver using a novel combining method is proposed, which can significantly simplify the receiver configuration. It achieves a power penalty variation of less than 0.6 dB due to polarisation changes.
GaInAs/InP I2L ring oscillators
- Author(s): P. Kurpas ; E. Woelk ; R. Mayer ; H. Beneking
- Source: Electronics Letters, Volume 25, Issue 15, p. 998 –999
- DOI: 10.1049/el:19890667
- Type: Article
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GaInAs/InP heterojunction bipolar transistors were fabricated and integrated to a seven-stage I2L ring oscillator. The transistors operating upside-down (inverted, collector on top) exhibit a current gain of 5. A delay time of 13 ns at a power consumption of 1.13mW/gate has been achieved for 40 × 75μm2 devices.
4 Gbit/s, 188 km optical fibre transmission experiment using three packaged laser amplifiers
- Author(s): H. Taga ; S. Yamamoto ; K. Mochizuki ; H. Wakabayashi
- Source: Electronics Letters, Volume 25, Issue 15, p. 999 –1000
- DOI: 10.1049/el:19890668
- Type: Article
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We report on 4 Gbit/s optical fibre transmission experiments using three packaged laser amplifiers as linear optical repeaters. With total amplifier gain 32 dBm, a directly modulated 1.518 μm DFB laser signal was transmitted over 188 km fibres, consisting of dispersion shifted fibres and conventional fibres for dispersion compensation. The overall system penalty was only 0.9 dB.
Combined space/time diversity technique for narrowband TDMA mobile radio systems
- Author(s): L.B. Lopes
- Source: Electronics Letters, Volume 25, Issue 15, p. 1001 –1002
- DOI: 10.1049/el:19890669
- Type: Article
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A new diversity technique is presented which employs antenna (space) diversity in conjunction with time staggering to allow the receiver to collect energy from several paths without phase or gain adjustments. The technique is particularly suited to narrowband TDMA where the receiver is likely to include an equaliser, and the resulting performance gains are characterised, taking the GSM system as an example.
New scheme for digital multisignatures
- Author(s): L. Harn and T. Kiesler
- Source: Electronics Letters, Volume 25, Issue 15, p. 1002 –1003
- DOI: 10.1049/el:19890670
- Type: Article
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When two individual users wish to carry on a secure conversation, they can use the well-known RSA public key cryptosystem in doing so. This cryptosystem provides to these users both data secrecy and digital signature in a very efficient manner. However, in many applications, multiple users need to sign a document. In this letter, we propose a modified scheme, based on the RSA scheme, which will allow any number of users to sign a document and send it secretly to the receiver. The length of ciphertext remains constant, no matter how great the number of signatories. The trade-off is that the processing times required for generating the multisignature, and for verifying multisignatures, depend on the number of signatories.
3 GHz optical soliton propagation using all laser diodes
- Author(s): K. Iwatsuki ; A. Takada ; S. Nishi ; M. Saruwatari
- Source: Electronics Letters, Volume 25, Issue 15, p. 1003 –1005
- DOI: 10.1049/el:19890671
- Type: Article
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Optical soliton propagation at a 3 GHz repetition rate is demonstrated using optical pulses from a gain-switched 1.55 μm distributed feedback laser diode. An Er3+-doped fibre amplifier and a Raman amplifier, both pumped by 1.47μm Fabry-Perot laser diodes, are employed for achieving high-peak-power optical pulses and fibre-loss compensation, respectively.
New algorithm for 2-D linear system eigenstructure assignment
- Author(s): Z. Geng and R.L. Carroll
- Source: Electronics Letters, Volume 25, Issue 15, p. 1005 –1006
- DOI: 10.1049/el:19890672
- Type: Article
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An algorithm for eigenstructure assignment of twodimensional linear systems is proposed, which reveals the degrees of freedom in selecting the feedback gain matrix of 2-D systems. Sufficient conditions for the existence of a linear state feedback gain matrix are given. By using the freedom which may be offered by these algorithms an output feedback controller can be designed to achieve the desired eigenstructure.
Finite-difference time-domain (FD-TD) analysis of discontinuities in homogeneous, dispersive waveguides
- Author(s): J.C. Olivier and D.A. McNamara
- Source: Electronics Letters, Volume 25, Issue 15, p. 1006 –1007
- DOI: 10.1049/el:19890673
- Type: Article
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p.
1006
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An absorbing boundary condition is given for the application of the pulsed incident electromagnetic field form of the finitedifference time-domain method to the analysis of waveguide discontinuities. Its application is illustrated by example.
Algorithms for converting convolutional codes from feedback to feedforward form and vice versa
- Author(s): J.-E. Porath
- Source: Electronics Letters, Volume 25, Issue 15, p. 1008 –1009
- DOI: 10.1049/el:19890674
- Type: Article
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Algorithms for conversion from feedforward (FF) to feedback (FB) codes and vice versa are presented. The former is based on a trellis search and the latter on an algebraic solution. The algorithms work on trellis codes of rate R = k/n.
High-quality dual-gate PMOS devices in local overgrowth (LOG)
- Author(s): R.P. Zingg ; B. Höfflinger ; G.W. Neudeck
- Source: Electronics Letters, Volume 25, Issue 15, p. 1009 –1010
- DOI: 10.1049/el:19890675
- Type: Article
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A new SOI technology is introduced with enhanced device performance and small geometries. The low-impurity crystalline SOI film is produced by local overgrowth (LOG) over an oxide, an important alternative to recrystallised silicon films for 3D-CMOS and SOI circuits. This technology was developed from epitaxial lateral overgrowth (ELO), to allow the use of the substrate as an interconnect layer and to enable access to submerged gates. Surface-channel mobilities are measured to be 165cm2/V s for PMOS devices built on top of the overgrowth and 160cm2/V s for devices with a submerged gate. The structures produced by LOG arc planar and allow for further stacking of devices.
Versatile polycrystalline silicon transistor/switching structure
- Author(s): A. Al-Bustani
- Source: Electronics Letters, Volume 25, Issue 15, p. 1011 –1012
- DOI: 10.1049/el:19890676
- Type: Article
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A simple p+n-polysilicon structure is proposed to perform either as a transistor or a two-state switching device. An outline theory is presented using a multigrain model for the polycrystalline silicon layer. Charging and discharging of traps at the grain boundaries are included in the theory. The effect of the recombination-generation mechanism in the neutral n2 silicon region is also taken into account.
Polarisation diversity receiver for coherent optical FSK communications using active weight controller
- Author(s): H. Kröner and G. Zimmer
- Source: Electronics Letters, Volume 25, Issue 15, p. 1013 –1014
- DOI: 10.1049/el:19890677
- Type: Article
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p.
1013
–1014
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A novel active baseband weight controller for polarisation diversity receivers is demonstrated. The measured receiver sensitivity degradation due to polarisation fluctuations is less than 0.51 dB at a bit error rate of 10−5. This corresponds to theoretical results, which are also derived for other detection and combining methods.
New two-way, 3 dB, equiphase, impedance-transforming power divider suitable for high-power applications
- Author(s): H.R. Mgombelo and H.O. Ali
- Source: Electronics Letters, Volume 25, Issue 15, p. 1014 –1016
- DOI: 10.1049/el:19890678
- Type: Article
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A new two-way, 3 dB, equiphase, impedance-transforming power divider suitable for high-power applications is presented. Design relations have been worked out and the performance characteristics computed for different impedance transformation ratios.
Erratum: Improved Rabin's scheme with high efficiency
- Author(s): L. Harn and T. Kiesler
- Source: Electronics Letters, Volume 25, Issue 15, page: 1016 –1016
- DOI: 10.1049/el:19890679
- Type: Article
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