Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 16, Issue 12, 5 June 1980
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Volume 16, Issue 12
5 June 1980
Velocity, electromechanical coupling factor and acoustic loss of surface shear waves propagating along x-axis on rotated Y-cut plates of LiNbO3
- Author(s): Hiroomi Kojima ; Yasuaki Kinoshita ; Mitsuaki Hikita ; Toyoji Tabuchi
- Source: Electronics Letters, Volume 16, Issue 12, p. 445 –446
- DOI: 10.1049/el:19800313
- Type: Article
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Velocity and propagation loss of surface shear waves are measured on free-space and metallised surfaces of LiNbO3 crystals along the x-axis of rotated Y-cut plates as a function of rotation about the x-axis between 35° and 70°. The coupling factor obtained from the velocities is 0.20 for a 35° rotated Y-cut plate and 0.09 for a 70° plate. The coupling factor changes linearly with the rotation angle. The propagation losses over the whole range measured here are less than 5 dB/cm on both free-space and on metallised surfaces. These losses are fairly low and very favourable for fabricating s.a.w. filters.
Resonant s.a.w. filter using surface shear wave mode on LiTaO3 substrate
- Author(s): Mitsutaka Hikita ; Yasuaki Kinoshita ; Hiroomi Kojima ; Toyoji Tabuchi
- Source: Electronics Letters, Volume 16, Issue 12, p. 446 –447
- DOI: 10.1049/el:19800314
- Type: Article
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A low-loss narrow band (below 3%) resonant filter has been achieved using twin-turn reflectors and a surface shear wave mode on 36° YX LiTaO3 substrate.
Filters using digital techniques to improve operation of a fast digital phasemeter
- Author(s): M. Durvaux
- Source: Electronics Letters, Volume 16, Issue 12, p. 447 –448
- DOI: 10.1049/el:19800315
- Type: Article
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The letter describes two filter circuits, both using digital techniques. These filters allow operation of a fast digital phasemeter, which is described, even when the signal/noise ratio is poor. It was developed initially for plasma electron density measurement on thermonuclear fusion experiments.
Frequency dependence of effective path length in prediction of rain attenuation statistics
- Author(s): H.N. Kheirallah ; J.P. Knight ; R.L. Olsen ; K.S. Mccormick ; B. Segal
- Source: Electronics Letters, Volume 16, Issue 12, p. 448 –450
- DOI: 10.1049/el:19800316
- Type: Article
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Theoretical and numerical results are presented which demonstrate that the effective path length commonly used in the prediction of rain attenuation statistics for earth-space paths is frequency dependent. Also presented is a method of translating effective path length measurements in frequency.
Subjective assessment method for television digital codecs
- Author(s): J.W. Allnatt
- Source: Electronics Letters, Volume 16, Issue 12, p. 450 –451
- DOI: 10.1049/el:19800317
- Type: Article
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Results of previous experiments to compare the performance of quality and impairment types of subjective grading scales for television pictures have been re-examined with particular reference to performance near the threshold of visibility. No evidence was found to suggest that the quality scale should be superseded for assessing television digital codecs.
Terminations for magnetostatic waves
- Author(s): W. Faber
- Source: Electronics Letters, Volume 16, Issue 12, p. 452 –453
- DOI: 10.1049/el:19800318
- Type: Article
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Magnetostatic wave (m.s.w.) devices can exhibit multiple reflections due to finite sample dimensions. By reducing the magnetic bias field in the end regions of the sample using soft iron rods, these reflections can be eliminated. This has been demonstrated by pulse delay measurements.
Moment-method solution of directed dipole antennas
- Author(s): R. Neri
- Source: Electronics Letters, Volume 16, Issue 12, p. 453 –455
- DOI: 10.1049/el:19800319
- Type: Article
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A range of directed dipole antennas is analysed for interdipole spacing of 0.10λ, 0.15λ, 0.20λ and 0.25λ, using driven and parasitic conductors of any length between 0.40λ and 0.58λ, and of both equal and unequal radius.
1.5–1.6 μm GaInAsP/InP Integrated twin-guide lasers with first-order distributed Bragg reflectors
- Author(s): K. Utaka ; K. Kobayashi ; K. Kishino ; Y. Suematsu
- Source: Electronics Letters, Volume 16, Issue 12, p. 455 –456
- DOI: 10.1049/el:19800320
- Type: Article
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The room-temperature operation of 1.5–1.6 μm GaInAsP/InP integrated twin-guide lasers with first-order distributed Bragg reflectors is reported. Single-longitudinal-mode oscillation was observed up to 1.4 times the threshold current. The temperature dependence of lasing wavelength was only 0.8 Å/degree.
Single-mode oscillation under high-speed direct modulation in GaInAsP/InP integrated twin-guide lasers with distributed Bragg reflectors
- Author(s): Y. Sakakibara ; K. Furuya ; K. Utaka ; Y. Suematsu
- Source: Electronics Letters, Volume 16, Issue 12, p. 456 –458
- DOI: 10.1049/el:19800321
- Type: Article
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Spectral behaviour of 1.3 μm GaInAsP/InP integrated twin-guide lasers with first-order distributed Bragg reflectors under high-speed direct modulation was measured. It was confirmed that stable single-longitudinal-mode operation is maintained for applied modulating current pulse width of only 1 ns. The rise time and width of the light output pulse were less than 0.3 and 3 ns, respectively.
7B8B balanced code with simple error detecting capability
- Author(s): R. Brooks
- Source: Electronics Letters, Volume 16, Issue 12, p. 458 –459
- DOI: 10.1049/el:19800322
- Type: Article
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A description is given of a simple in-service error detection technique suitable for use at dependent repeaters. The technique is similar to even mark parity error detection but differs in that no special signals such as parity check digits are required. In fact the line coding terminal equipment remains unmodified by the inclusion of this error detection technique.
Relationship between power added efficiency and gate-drain avalanche in GaAs m.e.s.f.e.t.s
- Author(s): S.H. Wemple ; M.L. Steinberger ; W.O. Schlosser
- Source: Electronics Letters, Volume 16, Issue 12, p. 459 –460
- DOI: 10.1049/el:19800323
- Type: Article
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–460
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Pulse avalanche measurements in the transistor three-terminal configuration reveal a correlation between pulse gate-drain avalanche and power added efficiency. This result, in conjunction with earlier work, points to simple design principles that can be used to maximise efficiency.
Sampling theorem application to s.a.w. diffraction simulation
- Author(s): T. Kodama
- Source: Electronics Letters, Volume 16, Issue 12, p. 460 –462
- DOI: 10.1049/el:19800324
- Type: Article
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Recent fast methods for simulating the diffraction effect on the frequency response for surface-acoustic-wave (s.a.w.) devices are improved so that they become more flexible and give a faster computational speed. The technique is based on the sampling theorem for time-limited signals.
Inclusion of amplifier finite gain and bandwidth in analysis of switched-capacitor filters
- Author(s): J. Lau and J.I. Sewell
- Source: Electronics Letters, Volume 16, Issue 12, p. 462 –463
- DOI: 10.1049/el:19800325
- Type: Article
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–463
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The exact mathematical solution of the amplifier finite gain and bandwidth problem in switched-capacitor filter networks is presented. The theory is incorporated into a computer analysis program and typical results for a filter circuit are included.
Simple self-centring technique for mounting microsphere coupling lens on a fibre
- Author(s): M.L. Dakss and B. Kim
- Source: Electronics Letters, Volume 16, Issue 12, p. 463 –464
- DOI: 10.1049/el:19800326
- Type: Article
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–464
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A simple and accurate self-centring method of mounting a microsphere coupling lens on a fibre endface is described. In over 85% of cases tried, the lenses were centred on the fibre axis to within 3 μm. The lenses yield a laser-fibre coupling efficiency of about 65%.
Estimating the pitch period of voiced speech
- Author(s): E. Ambikairajah ; M.J. Carey ; G. Tattersall
- Source: Electronics Letters, Volume 16, Issue 12, p. 464 –466
- DOI: 10.1049/el:19800327
- Type: Article
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–466
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In speech processing an estimation of the speech pitch period is important. Real time pitch detection is only possible by the selection of an efficient algorithm suitable for implementation on a programmable processor or in special-purpose hardware. The use of the periodogram algorithm (p.a.) is proposed to detect the pitch period of voiced speech. This algorithm is attractive for the following reasons: (a) it has no multiply operation; (b) when implemented on a 16-bit computer (e.g. microprocessor) the computation can be done in integer arithmetic without exceeding the microprocessor's dynamic range; (c) it is a simple technique for estimating the pitch period with reasonable accuracy. Results of the analysis of speech signals and sinusoids using the periodogram algorithm are presented and comparisons are made with the average magnitude difference function (a.m.d.f.) which is an alternative method of estimating the pitch period of the voiced speech.
Practical realisation of mod p, p prime multiplier
- Author(s): A.S. Ramnarayan
- Source: Electronics Letters, Volume 16, Issue 12, p. 466 –467
- DOI: 10.1049/el:19800328
- Type: Article
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A practical realisation of a mod p, p prime multiplier for the case p = 2n−2k+1, k<n is described. Simulated results are presented and speed metrics based on state-of-the-art memory technology are computed.
Impact ionisation in multilayered heterojunction structures
- Author(s): R. Chin ; N. Holonyak ; G.E. Stillman ; J.Y. Tang ; K. Hess
- Source: Electronics Letters, Volume 16, Issue 12, p. 467 –469
- DOI: 10.1049/el:19800329
- Type: Article
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Calculations are reported showing that in multilayered heterojunction structures the effective impact ionisation rates for electrons and holes can be very different, even if they are the same in the basic bulk materials. The reason for this is the difference in the band-edge discontinuities for electrons and holes and the lower phonon mean free path for holes in quantum well structures.
Effect of deposition rate on spectral loss of GeO2-P2O5-SiO2 graded index fibres
- Author(s): S.R. Nagel and M.A. Saifi
- Source: Electronics Letters, Volume 16, Issue 12, p. 469 –470
- DOI: 10.1049/el:19800330
- Type: Article
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Low loss, low OH content 0.23 n.a. graded index germanium phosphosilicate fibres have been fabricated using the m.c.v.d. process at rates up to 0.34 g/min with deposited layer thicknesses up to 16 μm. The deposition rate did not affect achievement of low loss in the spectral range 0.7 μm–1.7 μm.
Generation of surface acoustic waves by means of a c.w. laser
- Author(s): E.A. Ash ; E. Dieulesaint ; H. Rakouth
- Source: Electronics Letters, Volume 16, Issue 12, p. 470 –472
- DOI: 10.1049/el:19800331
- Type: Article
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Acoustic surface waves have been generated in a solid by using a c.w. laser modulated at 10 MHz. The arrangement is regarded as potentially useful for a nondestructive testing system in which both the generation and the detection of surface waves is effected by means of a laser.
Parasitics-insensitive switched-capacitor ladder filters
- Author(s): Man Shek Lee
- Source: Electronics Letters, Volume 16, Issue 12, p. 472 –473
- DOI: 10.1049/el:19800332
- Type: Article
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A simple method for designing parasitics-insensitive switched-capacitor (s.c.) ladder filters is described. The response of the s.c. filter is related to that of a continuous-time prototype circuit by the bilinear z-transform.
Estimation of a sinusoid in uncorrelated noise using adaptive line enhancer
- Author(s): V. Umapathi Reddy
- Source: Electronics Letters, Volume 16, Issue 12, p. 473 –475
- DOI: 10.1049/el:19800333
- Type: Article
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In applications of adaptive line enhancers (a.l.e.) for detecting sinusoidal signals in uncorrelated noise, an arbitrary value of delay Δ, the decorrelation parameter, is suggested and Δ = 1 is normally used. Exact analysis of the a.l.e. for the case of a single sinusoid in uncorrelated noise shows that an optimum value of Δ exists for which the a.l.e. yields much better estimate of the sinusoid frequency compared to that with Δ = 1. The simulation results show an excellent agreement with the predicted behaviour.
Novel phase lead inverting integrator and its application in two-integrator loop filters
- Author(s): A.M. Soliman
- Source: Electronics Letters, Volume 16, Issue 12, p. 475 –476
- DOI: 10.1049/el:19800334
- Type: Article
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A new variable phase inverting integrator is given. The proposed integrator is suitable for phase correction in the two integrator 1 filters.
Short-channel polysilicon-gate m.o.s.f.e.t.s fabricated by c.w. argon laser annealing of arsenic-implanted source and drain
- Author(s): T.C. Teng ; J.D. Merritt ; J. Velez ; J. Peng ; L. Palkuti
- Source: Electronics Letters, Volume 16, Issue 12, p. 477 –478
- DOI: 10.1049/el:19800335
- Type: Article
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Short-channel polysilicon-gate n-channel m.o.s.f.e.t.s have been successfully fabricated using c.w. argon laser annealing of arsenic-implanted source and drain. The turn-on voltage is higher for the laser annealed devices than for those annealed thermally, which were processed identically except for the source and drain annealing. Laser annealing also reduced the n+-layer sheet resistance to about half that of the thermally annealed n+ regions.
Transmission characteristics of 116.3 km and 65.1 km graded-index v.a.d. fibres at 1.55 μm and 1.3 μm
- Author(s): T. Edahiro ; M. Kawachi ; S. Sudo ; H. Nagai
- Source: Electronics Letters, Volume 16, Issue 12, p. 478 –480
- DOI: 10.1049/el:19800336
- Type: Article
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Seven long pieces of fibre with low loss and wide bandwidth properties made by the v.a.d. method were spliced with V-grooves into an 116.3 km graded-index fibre, and three long pieces of fibre into a 65.1 km fibre. Transmission characteristics of these graded-index fibres were measured with a swept-frequency method using InGaAsP/InP b.h. laser diodes operating at 1.55 μm (made by low temperature liquid-phase epitaxial growth) and 1.3 μm, respectively. The overall transmission losses and 6 dB down electrical bandwidths at the two wavelengths were 37 dB and 16.5 MHz, 35.2 dB and 36.5 MHz, respectively.
Strays-insensitive active switched-capacitor biquad
- Author(s): E.I. El-Masry
- Source: Electronics Letters, Volume 16, Issue 12, p. 480 –481
- DOI: 10.1049/el:19800337
- Type: Article
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A general active switched-capacitor biquad is introduced. The circuit is immune to the various parasitic capacitances and is based on the two-integrator-loop topology. It implements the noninverting forward-Euler and the inverting backward-Euler discrete integrators. The circuit is the most general of its kind and all published biquads and many others can be generated from it.
Novel insensitive lossless inductor simulation through inverse function generation
- Author(s): R. Nandi
- Source: Electronics Letters, Volume 16, Issue 12, p. 481 –483
- DOI: 10.1049/el:19800338
- Type: Article
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This communication describes a new method of active lossless single-element controlled inductor simulation by realising a function H = [1 − (Y2/Y1)]−1 with a negative impedance convertor block (n.i.c.) and then generating 1/H by an infinite-gain operational amplifier (o.a.). Suitable resistive feedback is then applied to synthesise Yin = Yo (1 − H−1) = Y0Y2/Y1 which yields a lossless inductor with Y1 = sC, Y0 = 1/R0 and Y2 = 1/R2. The lossless inductor is shown to be insensitive to active parameter changes with an appropriate choice of the active elements such as the n.i.c. implementation with a second generation current conveyor (c.c.II) and inverse generation by an o.a.
Deep trapping centres in n-GaAs surface barrier diodes for nuclear radiation detection
- Author(s): S.J. Pearton ; A.J. Tavendale ; A.A. Williams
- Source: Electronics Letters, Volume 16, Issue 12, p. 483 –484
- DOI: 10.1049/el:19800339
- Type: Article
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Deep level transient spectroscopy has been applied for the first time in the study of deep level trapping centres in n-GaAs nuclear radiation detectors. Devices from bulk and epitaxial material with net donor impurity densities from 5×1013 to 3×1016 cm−3 have been studied and several common levels observed. The Poole-Frenkel effect has been identified in three levels (Ev+0.19 eV, Ec−0.62 eV, Ec−0.73 eV) in the epitaxial GaAs. A value for the Poole-Frenkel constant of β = 4.7±1.4×10−4 eV V−½ cm½ was obtained for the Ec−0.62 eV level, compared to the theoretical value for GaAs, 2.3×10−4 eV V−1/2 cm1/2.
Spiral antenna with integrated detector
- Author(s): T. Thorvaldesen
- Source: Electronics Letters, Volume 16, Issue 12, p. 484 –486
- DOI: 10.1049/el:19800340
- Type: Article
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A spiral antenna for the detection of pulsed signals in the 2.5–18 GHz range has been built and tested. The antenna has a detector diode mounted directly on the spiral itself, thereby eliminating the need for a balun. A description of the antenna and its electrical characteristics is given.
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