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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 27, Issue 13, 20 June 1991

Volumes & issues:

Volume 27, Issue 13

20 June 1991

QAM signal synthesis by time division multiplexing
Relationship between two algorithms for discrete cosine transform
Narrow line semiconductor laser using fibre grating
  • Author(s): D.M. Bird ; J.R. Armitage ; R. Kashyap ; R.M.A. Fatah ; K.H. Cameron
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1115 –1116
  • DOI:  10.1049/el:19910696
  • Type: Article
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  • p. 1115 –1116 (2)
    A narrow linewidth, low chirp, wavelength selectable, packaged alternative to current DFB structures has been developed which employs a fibre reflection grating incorporated in the fibre pigtail. The wavelength of the packaged device can be determined by the appropriate choice of fibre grating coupled to the antireflection coated facet of a 1.55μm BH laser. Linewidths of less than 50 kHz, sidemode suppression of more than 30 dB and chirp when modulated at 1.2 Gbit/s of <0.5 MHz have been demonstrated.
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Selfaligned InGaAs/InP heterostructure bipolar transistors
  • Author(s): A. Feygenson ; H. Temkin ; W.T. Tsang ; L. Yang ; R.D. Yadvish ; P.F. Scortino
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1116 –1118
  • DOI:  10.1049/el:19910697
  • Type: Article
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  • p. 1116 –1118 (3)
    InGaAs/InP heterostructure bipolar transistors have been realised using a new selfaligned process. Transistor wafers were grown by chemical beam epitaxy. Ideality factors close to unity were measured for emitter-base and collector-base diodes. The resulting devices exhibit nearly constant gain over four orders of magnitude of collector current densities, from j = 1.5 × 10−4 A/cm2 to 1.5 A/cm2.
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Three-dimensional analysis of multiquantum well DFB lasers
Analysis of below-threshold spectrum and linewidth of surface-emitting λ/4-shifted DFB lasers with DBR mirror
Breaking public key cryptosystem based on systems of nonlinear equations over finite field
20 dB gain thulium-doped fluorozirconate fibre amplifier operating at around 0.8 μm
Latch up in physically merged bipolar-MOS BICMOS structures
Two interpolative BTC image coding schemes
  • Author(s): B. Zeng
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1126 –1128
  • DOI:  10.1049/el:19910703
  • Type: Article
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  • p. 1126 –1128 (3)
    Two interpolative BTC image coding schemes with optimal stack filters (in the minimum MAE sense) as the interpolator are suggested. Compared to the standard BTC, the new schemes yield >25% and >37.5% reductions in bit rate, respectively, with little performance degradation. Compared to a previous interpolative BTC coding method, the quality of coded images has been greatly improved with the new schemes (at the same or even a lower rate).
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Modular FET model with distributed source configuration for single and double side source grounded MESFET
  • Author(s): G. Baumann  and  R. Hierl
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1128 –1129
  • DOI:  10.1049/el:19910704
  • Type: Article
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  • p. 1128 –1129 (2)
    A new approach for accurately modelling MESFETs and HEMTs up to the high millimetre-wave range is described. The use of a distributed source configuration allows the characterisation of both single side grounded (SSG) and double side grounded (DSG) FETs in the common source and also in the reverse channel circuit configuration. The model has been verified up to 40 GHz with excellent results. To our knowledge the effect of SSG has not been examined yet by any commercial CAD tool.
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Improved coupling for aperture coupled microstrip antennas
  • Author(s): D.M. Pozar  and  S.D. Targonski
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1129 –1131
  • DOI:  10.1049/el:19910705
  • Type: Article
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  • p. 1129 –1131 (3)
    An aperture shape that gives significantly improved coupling for an aperture coupled microstrip antenna is described. This ‘dogbone’ aperture consists of the usual rectangular slot, augmented with loading slots at each end. Measured data show an increase of more than three for the resonant input impedance of an antenna using the dogbone-shaped aperture, as compared with the input impedance of the same antenna with a rectangular slot of the same overall length. The field distributions of both slots are also measured, and compared.
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Compensation for temperature dependence of Faraday effect in diamagnetic materials: application to optical fibre sensors
Efficient VLSI digital logarithmic codecs
  • Author(s): B. Hoefflinger
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1132 –1134
  • DOI:  10.1049/el:19910707
  • Type: Article
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  • p. 1132 –1134 (3)
    N bit digital words can be logarithmically encoded and compressed to a word length of (log2n + m − 1) bit maintaining a relative accuracy of m bit over (n − m) octaves of signal level. A bit-serial VLSI coder is reported, which requires little more than a log2n counter and an output register and it has a latency of one wordlength. The bit-parallel coder can be built with less than n2 transistors and has less than n/4 gate delays. The decoder has similar properties and it expands the logarithm to an antilogarithm with n bit of dynamic range. Using these codecs, digital multiplication, division, powers and roots are reduced to additions, subtractions and shifts, respectively.
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Comparison between free space and in-waveguide power measurement standards at 94 GHz
Pseudo-N-path switched capacitor filters with out-of-band noise peaks
Fast vicinity-upgrade algorithm for rectilinear steiner trees
  • Author(s): J.K. Chua  and  Y.C. Lim
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1139 –1141
  • DOI:  10.1049/el:19910710
  • Type: Article
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  • p. 1139 –1141 (3)
    A new algorithm for rectilinear Steiner trees (RST) is presented. The proposed algorithm is based on successively constructing a vicinity structure from a rectilinear minimum spanning tree (MST) and generating a refined RST. The algorithm achieves an 8.5–10% average cost improvement over the rectilinear MST at a time complexity of O(n log n). To address specifically the linear programming approach of global routing, the algorithm is modified to generate K trees.
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All-fibre frequency shifters using multiple acoustic transducers
Improved design procedure for multiplierless FIR digital filters
Observation of ballistic transport in hot-electron vertical FET spectrometer using ultrathin planar-doped barrier launcher
Millimetre wave performance of carbon-doped-base AlGaAs/GaAs HBTs
Tracking performance of digital chip synchronisation algorithms for bandlimited direct-sequence spread-spectrum communication
High performance W-band InAlAs-InGaAs-InP HEMTs
  • Author(s): D.C. Streit ; K.L. Tan ; R.M. Dia ; A.C. Han ; P.H. Liu ; H.C. Yen ; P.D. Chow
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1149 –1150
  • DOI:  10.1049/el:19910716
  • Type: Article
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  • p. 1149 –1150 (2)
    0.15 μm T-gate lattice-matched In0.52Al0.48AsIn0.53Ga0.47As-InP HEMTs with a device minimum noise figure of 1.7dB with 7.7 dB associated gain at 93 GHz have been fabricated. A single-ended active mixer was fabricated using these devices, and a conversion gain of 2.4 dB was measured with 7.3 dB single-sideband noise figure at 94 GHz. This is the first reported active mixer conversion gain at W band.
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Correlation between linewidth rebroadening and low-frequency RIN enhancement in semiconductor lasers
New measurement technique for waveguide losses based on photoluminescence
Platinum silicide fusion bonding
  • Author(s): M.S. Ismail  and  R.W. Bower
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1153 –1155
  • DOI:  10.1049/el:19910719
  • Type: Article
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  • p. 1153 –1155 (3)
    Silicide direct bonding has been accomplished between silicon PtSi coated wafers and both PtSi coated and uncoated silicon wafers. Successful bonding occurred when the PtSi surface was rendered hydrophilic by a hot aqua regia selective etching and cleaning process. The PtSi provides bondable, relatively low resistance paths which provide electrical interconnections between circuit elements on the bonded pair of wafers.
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Low-loss Ka-band frequency selective subreflector
Red upconversion Yb-sensitised Pr fluoride fibre laser pumped in 0.8 μm region
  • Author(s): J.Y. Allain ; M. Monerie ; H. Poignant
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1156 –1157
  • DOI:  10.1049/el:19910721
  • Type: Article
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  • p. 1156 –1157 (2)
    Room temperature upconversion lasing has been obtained at 635 nm in Yb : Pr codoped fluoride fibre pumped in the 0.8μm region. Yb3+ is excited by ground state absorption and transfers energy to the 1G4 level of Pr3+, which is then brought into the 3P0 level by excited state absorption. Extracted powers in excess of 20 mW at 635 nm and a slope efficiency of 10% were observed for 840–850 nm.
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Arithmetic coding with limited past history
Adaptive chirplet representation of signals on time–frequency plane
  • Author(s): D. Mihovilovic  and  R.N. Bracewell
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1159 –1161
  • DOI:  10.1049/el:19910723
  • Type: Article
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  • p. 1159 –1161 (3)
    Dynamic spectra, which exhibit the spectral content of a signal as time elapses, are based on subdivision of the time–frequency plane into minimum-area rectangular cells. The cell dimensions in time and frequency are usually held constant throughout. A more general spectral analysis would allow the cells to change aspect ratio with time. Elementary cells assuming oblique forms (chirplets) are proposed, together with an adaptive method for selecting their aspect ratio and obliquity to suit the data.
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Simple high-frequency diffraction analysis of microstrip antenna on large cylinder
  • Author(s): C.-F. Huang
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1161 –1163
  • DOI:  10.1049/el:19910724
  • Type: Article
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  • p. 1161 –1163 (3)
    The aim of this Letter is to investigate the electromagnetic field surrounding an electrically large convex cylinder on which a microstrip antenna is mounted. Being capable of calculating the various types of field, i.e. directly incident field, reflected field and diffracted field on the plane perpendicular to the cylinder axis, the selfconsistent GTD formulation is employed. In accordance with such a formulation, a two-magnetic-line-current radiation model for the patch is given. Measurement is also performed in a microwave anechoic chamber for the purpose of validation of the proposed theory.
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Determining mixer diode positions of microwave Doppler with-sense module
All-optical remote gain switching in Er-doped fibre amplifiers
  • Author(s): M. Zirngibl
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1164 –1166
  • DOI:  10.1049/el:19910726
  • Type: Article
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  • p. 1164 –1166 (3)
    A novel, all-optical feedback scheme that allows remote optical gain switching in Er-doped fibre amplifiers is demonstrated. A selected wavelength of the amplified spontaneous emission (ASE) at the output of the amplifier is fed back to the input through an unpumped Er-doped fibre acting as a saturable absorber. Off and on switching of ring lasing (and hence, respectively, on and off switching of the amplifier gain) is achieved by remotely injecting optical control signals at appropriate wavelengths over the transmission fibre. A gain bistability (on–off ratio) of 26 dB at 1530 nm is demonstrated. A switching time of 10–50 ms was observed, inherent to the erbium fluorescence lifetime. This scheme could be useful in directing traffic flow in optical networks.
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High performance W-band low-noise pseudomorphic InGaAs HEMT MMIC amplifiers
  • Author(s): K.L. Tan ; H. Wang ; D.C. Streit ; P.H. Liu ; R.M. Dia ; A.C. Han ; D. Garske ; S. Bui ; J.K. Liu ; T.S. Lin ; G.S. Dow ; P.D. Chow ; J. Berenz
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1166 –1167
  • DOI:  10.1049/el:19910727
  • Type: Article
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  • p. 1166 –1167 (2)
    State of the art W-band low noise MMICs have been fabricated using pseudomorphic InGaAs HEMTs with a 0.1 μm gate length. A two-stage LNA fabricated using this process has achieved a gain of 13.3 dB at 94 GHz and 17 dB at 89 GHz, with a noise figure of 5.5 dB at 94 GHz. These results are the best reported to date for any MMIC LNA fabricated on both GaAs and InP substrates at this frequency range.
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Low complexity soft decision decoding technique for T-user collaborative coding multiple-access channels
  • Author(s): F. Ali  and  B. Honary
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1167 –1169
  • DOI:  10.1049/el:19910728
  • Type: Article
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  • p. 1167 –1169 (3)
    The collaborative coding multiple-access (CCMA) scheme permits potentially efficient simultaneous transmission by several users sharing a common channel, without subdivision in time or frequency. A new low complexity soft decision decoding technique is introduced to make use of the CCMA error control capability. The proposed soft decision CCMA (SD CCMA) decoding algorithm for the T-user baseband CCMA adder channel is presented. Theoretical simulation results of the probability of error for a particular two-user CCMA scheme is also given using SD CCMA and hard decision (HD CCMA) decoding techniques.
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Composite events: computationally efficient method for generating 1/f noise
  • Author(s): N.J. Arnold  and  G. Wade
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1169 –1171
  • DOI:  10.1049/el:19910729
  • Type: Article
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  • p. 1169 –1171 (3)
    The task of generating 1/f noise via the random pulse train method is inherently numerically intensive. The computational efficiency has been increased by ten orders of magnitude by combining many elementary events into a single composite event. This approach is used to efficiently generate 1/f noise over a finite bandwidth. Further investigation and generalisation of the method may be of use to advancing the theory of 1/fnoise.
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Raman amplification of gain switched laser diode signal at 1.35μm to soliton power levels
Chaotic behaviour in current-mode controlled DC–DC convertor
14 GHz low-power highly sensitive static frequency divider using quantum well AlGaAs/GaAs/AlGaAs FET technology
  • Author(s): P. Wennekers ; A. Huelsmann ; G. Kaufel ; K. Koehler ; B. Raynor ; J. Schneider
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1173 –1175
  • DOI:  10.1049/el:19910732
  • Type: Article
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  • p. 1173 –1175 (3)
    A 14 GHz static frequency divider has been fabricated using an enhancement/depletion 0.3 μm recessed-gate AlGaAs/GaAs/AlGaAs quantum well FET process. The divider has a power dissipation of 35 mW at a supply voltage of 1.80 V. The minimum input power for dividing operation is 8.3 dBm at a maximum input frequency of 14.2 GHz, which is lowered to −6.2 dBm, when operating at 12.0 GHz.
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AlGaAs/GaAs based HEMTs, inverters, and ring oscillators with InGaAs, and AlGaAs etch-stop layers
  • Author(s): F. Ren ; S.J. Pearton ; R.F. Kopf ; S.N.G. Chu ; S.S. Pei
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1175 –1177
  • DOI:  10.1049/el:19910733
  • Type: Article
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  • p. 1175 –1177 (3)
    Direct coupled FET logic (DCFL) inverters and 19 stage ring oscillators have been demonstrated with MBE grown AlGaAs/GaAs HEMTs using a dry-etching gate recess technology. Pseudomorphic In0.3Ga0.7As and Al0.3Ga0.7As were used as etch-stop layers for depleted (D) mode ungated, saturated resistors and enhancement (E) mode FETs, respectively, to achieve excellent uniformities of threshold voltage and saturation current. The maximum extrinsic transconductance of 1.2 μm gate length devices was 289 mS/mm with 1.35 Ωmm source resistance. The logic swing and noise margins were 0.5 and 0.2 V, respectively. The propagation delay of a 19 stage ring oscillator was 31.5 ps/stage at 300°C.
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Current–voltage characteristics of bend in mesoscopic wire
Insight into operation of kulpa boundary distance measure
New low-complexity decision feedback equalisation technique for narrowband digital cellular systems
Current-mode allpass filter using FTFN with grounded capacitor
New bit-serial systolic multiplier for GF(2m) using irreducible trinomials
Design of differential QPSK modulator
  • Author(s): R.S. Bokulic
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1185 –1186
  • DOI:  10.1049/el:19910739
  • Type: Article
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  • p. 1185 –1186 (2)
    A differential QPSK modulator operating at a centre frequency of 847.5 MHz and an input data rate of 25 Mbit/s is described. The modulator incorporates a simple differential encoder design that interfaces directly to the RF section without the need for special driver circuitry. The RF section uses modular ‘building block’ components that can be changed relatively easily to support a wide range of centre frequencies.
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Experimental investigation of three-layer electromagnetically coupled circular microstrip antennas
  • Author(s): U.K. Revankar  and  A. Kumar
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1187 –1189
  • DOI:  10.1049/el:19910740
  • Type: Article
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  • p. 1187 –1189 (3)
    The broadband behaviour of a three-layer electromagnetically coupled circular microstrip antenna is investigated experimentally. The effects of interlayer spacings and the thickness of the parasitic layers on the impedance bandwidth, 3 dB beamwidth and pattern shape, are studied. Experiments show that this structure can provide a frequency bandwidth as high as 20% with a low crosspolarisation level and a moderately high gain.
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High speed operation of hybrid CMOS vertical cavity surface emitting laser array
  • Author(s): A.C. Von lehmen ; T.C. Banwell ; R. Cordell ; C. Chang-hasnain ; J.W. Mann ; J. Harbison ; L. Florez
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1189 –1191
  • DOI:  10.1049/el:19910741
  • Type: Article
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  • p. 1189 –1191 (3)
    The first successful hybrid integration of Si CMOS drivers with InGaAs/GaAs vertical cavity surface emitting (VCSE) laser arrays operating at bit rates up to 622Mbit/s is described. This technology has potential for low cost, highbandwidth communication links in optical interconnect and optical computing applications. The simple, power-efficient driver circuits were implemented in a standard 1.0 μm CMOS process.
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Wide bandwidth multiple quantum well 1.55 μm lasers
Closed-loop balancing and singular perturbation: a new result
Static scattering in filled nematic: new liquid crystal display technique
Analysis of effects of quantisation in multilayer neural networks using statistical model
Module orientation algorithm using reconstruction of nets and mean field annealing
Wavelength-insensitive couplers in form of all-fibre Mach–Zehnder interferometer
Taper coupling of laser diode to singlemode fibre: influence of fibre field shape
  • Author(s): Tong-Ning Li  and  W. Freude
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1202 –1203
  • DOI:  10.1049/el:19910748
  • Type: Article
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  • p. 1202 –1203 (2)
    The coupling efficiency of laser diodes to lensed down-tapered singlemode fibres was measured at λ = 1.318 μm and compared to theoretical results, taking into account the spherical aberration of the taper lens. Good agreement was found irrespective of the details of the fibre near-field function. However, the coupling distance between laser and fibre for maximum efficiency depends strongly on the shape of the fibre mode, and was measured to be (25±5) μm for the configuration presented. Assuming a Bessel field function, an optimum distance of 29 μm is predicted as compared to 39 μm for a Gaussian.
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Criteria for low-noise switched capacitor circuit design
Bit error rate measurement with predetermined confidence
Tuning capability of binary perceptron
  • Author(s): N.N. Biswas  and  S.K. Bhattacharyya
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1206 –1207
  • DOI:  10.1049/el:19910751
  • Type: Article
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  • p. 1206 –1207 (2)
    A theorem called the tuning theorem, which brings out the tuning capability of perceptrons where both the inputs and outputs are binary, has been stated and proved. It has been shown how with the help of this property, an associative memory has been developed with a single layer of perceptrons working as a massively parallel machine, rather than as a fully connected iterative Hopfield network.
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Ferroelectric-domain inversion induced by SiO2 cladding for LiNbO3 waveguide SHG
Ultrafast multibeatlength all-optical fibre switch
Comment: Optimised implementation of real-time discrete Wigner distribution
Integrated acousto-optic collinear TE–TM mode convertors for 0.8 μm optical wavelength range
Multiply-graded InGaAlAs heterojunction bipolar transistors
  • Author(s): J.C. Vlcek  and  C.G. Fonstad
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1213 –1215
  • DOI:  10.1049/el:19910756
  • Type: Article
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  • p. 1213 –1215 (3)
    InGaAlAs/InP double heterojunction bipolar transistors with continuously graded base–emitter and base–collector junctions were successively fabricated, and their DC characteristics measured. The devices exhibited a lower offset voltage (Voffset <20 mV), lower output conductance and higher collector–emitter breakdown voltage (BVCEO >13 V, BVCBO > 20V) than are typically achieved in single heterojunction InGaAlAs devices.
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Burst error correction capability of square array codes
  • Author(s): A.O. Mabogunje  and  P.G. Farrell
  • Source: Electronics Letters, Volume 27, Issue 13, p. 1215 –1216
  • DOI:  10.1049/el:19910757
  • Type: Article
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  • p. 1215 –1216 (2)
    The burst error correcting capabilities of binary block array codes have been investigated by various authors, 1–4 and it has been proved1 that the best single burst correcting codes belong to a class of array codes. This Letter contributes to the body of knowledge on array codes by proving that the length b of a burst error correctable by a square array code is bounded by b ≤ n2 − 1/2n + 1 when a diagonal readout with r = 1 is used. It is also shown that the burst error correction efficiency of square array codes tends to 1/2; for large n.
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Variable sensitivity photodetector for dynamic optical neurochip
Effect of dielectric protecting superstrate on radiation pattern of microstrip patch antenna
Erratum: Demonstration of birefringent optical fibre frequency shifter employing torsional acoustic waves
Erratum: Measurement of surface resistance of high-Tc superconductor by use of dielectric resonator
Erratum: Semi-insulating layers in InP obtained by Co or Fe ion implantation
Erratum: Efficient hardware decoding method for modified Huffman code
Erratum: Cryogenic operation of GaAs bipolar transistors with inverted base doping
Erratum: Optical feedback receiver with sensitivity of −55.2 dBm at 8 Mbit/s

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