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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 20, Issue 7, 29 March 1984

Volumes & issues:

Volume 20, Issue 7

29 March 1984

Gbit/s modulation of heavily Zn-doped surface-emitting InGaAsP/InP DH LED
Noise and dynamical gain studies of GaAs photoconductive detectors
  • Author(s): J.P. Vilcot ; D. Decoster ; L. Raczy ; M. Constant
  • Source: Electronics Letters, Volume 20, Issue 7, p. 274 –275
  • DOI:  10.1049/el:19840187
  • Type: Article
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  • p. 274 –275 (2)
    Noise measurements on N-type GaAs planar photoconductive detectors have been made over the 10 MHz–1.5 GHz frequency range. The dynamical gains of the devices were calculated from noise data and compared with the values obtained using picosecond measurements. In the gigahertz frequency domain, the photodetectors have an internal current gain as observed in the avalanche photodiodes, but no excess noise factor has been found.
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Effects of diffraction on frequency response of bulkacoustic-wave-beam filters
  • Author(s): M. Yamaguchi ; K.Y. Hashimoto ; M. Tanno ; H. Kogo
  • Source: Electronics Letters, Volume 20, Issue 7, p. 275 –277
  • DOI:  10.1049/el:19840188
  • Type: Article
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  • p. 275 –277 (3)
    The letter deals with the effects of diffraction or beam spreading on frequency response of bulkacoustic-wave-beam filters. Theoretical analysis for 41°-rotated Y-cut LiNbO3 has shown that, when the propagation distance is comparable to the acoustic length of the interdigital transducers (IDTs), the bandwidth is significantly increased over the SAW response with the same IDTs. If the propagation distance is within several times the IDT acoustic length, insertion loss is almost independent of propagation distance. These results suggest that there may be a situation where an increased fractional bandwidth for a given insertion loss is achievable. An experimental result was compared with the theoretical calculation.
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Nondissipative switched networks for high-power applications
Formant coding of speech using dynamic programming
Double mandrel: a modified technique for studying static fatigue on optical fibres
Digital fibre transmission using optical homodyne detection
Hydroxyl group formation caused by hydrogen diffusion into optical glass fibre
  • Author(s): S. Tanaka ; M. Kyoto ; M. Watanabe ; H. Yokota
  • Source: Electronics Letters, Volume 20, Issue 7, p. 283 –284
  • DOI:  10.1049/el:19840193
  • Type: Article
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  • p. 283 –284 (2)
    Transmission loss increase of optical glass fibre caused by hydrogen diffusion is measured as a function of temperature and partial pressure of hydrogen gas. The activation energy of hydroxyl group formation from the diffused molecular hydrogen was found to be 15.9 kcal/mole. Also the hydroxyl absorption loss increase at 200°C was found to be proportional to the square root of the partial pressure of hydrogen gas.
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Optical readout of resonant quartz sensors
Improved-dynamic-range single-mode OTDR at 1.3 μm
Photochromic waveguides and fibres
0.5 W 2–21 GHz monolithic GaAs distributed amplifier
  • Author(s): B. Kim  and  H.Q. Tserng
  • Source: Electronics Letters, Volume 20, Issue 7, p. 288 –289
  • DOI:  10.1049/el:19840197
  • Type: Article
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  • p. 288 –289 (2)
    A novel circuit concept to reduce the gate loss using series capacitors on the gate feeding lines has been implemented for a distributed amplifier design. It has significantly increased the gate width of an amplifier with a resultant increase of the broadband output power and efficiency. A monolithic GaAs distributed amplifier using 6 × 300 μm FETs has achieved a record output power of 0.5 W over the 2 to 21 GHz frequency band with at least 4 dB gain. The poweradded efficiency was 14%. The linear gain was 5 ± 1 dB over the same frequency band.
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Fabrication of ultra-thin free-standing wires of silicon nitride
Complex permittivity of a dielectric mixture: modified Fricke's formula based on logarithmic law of mixing
  • Author(s): S. Kisdnasamy  and  P.S. Neelakantaswamy
  • Source: Electronics Letters, Volume 20, Issue 7, p. 291 –293
  • DOI:  10.1049/el:19840199
  • Type: Article
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  • p. 291 –293 (3)
    A closed-form expression for the complex permittivity of a dielectric mixture consisting of random ellipsoidal inclusions in a continuous medium is derived by modifying the well known Fricke formula so as to be compatible with Lichte-necker's logarithmic law of mixing. Calculated results are compared with those of other theoretical models and some experimental data available elsewhere.
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Improved recognition of thermal structures by microwave radiometry
Current gain of silicon bipolar transistor with polysilicon emitter contact
  • Author(s): S.K. Mehta
  • Source: Electronics Letters, Volume 20, Issue 7, p. 294 –295
  • DOI:  10.1049/el:19840201
  • Type: Article
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  • p. 294 –295 (2)
    A two-region analysis is presented to predict the common-emitter current gain of a bipolar transistor with the polysilicon contact to the emitter for a case when the recombinations at the mono-poly interface are not negligible. The calculated current-gain enhancement for typical device parameters and for different values of interface recombination velocity show that the current-gain enhancement and its increase with decrease of emitter width is smaller for the interface with larger recombinations.
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Reactive ion etched GaAs optical waveguide modulators with low loss and high speed
High-efficiency Q-band GaAs FET oscillator
CMOS circuits made in lamp-recrystallised silicon-on-insulator
  • Author(s): D.P. Vu ; C. Leguet ; M. Haond ; D. Bensahel ; J.P. Colinge
  • Source: Electronics Letters, Volume 20, Issue 7, p. 298 –299
  • DOI:  10.1049/el:19840204
  • Type: Article
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  • p. 298 –299 (2)
    Polysilicon film was deposited on 100 mm oxidised silicon wafers. The film was recrystallised using a focused halogen lamp and served as substrate material for CMOS circuit fabrication. A mobility of 480 and 180 cm2/V s is found in N- and P-channel MOS transistors, respectively, and the threshold voltage spread is very low. 65-stage ring oscillators were also realised, which exhibit a 6 ns delay per stage at 5 V supply voltage.
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565 Mbaud 100 km optical system trial using a ridge waveguide DFB laser at 1.478 μm
Number representations for prime length DFTs
Energy efficiency of allpass ARMA impulse-equivalent periodic sequences
Optical fibres coated with a UV-curable material at a speed of 12 m/s
  • Author(s): U.C. Paek  and  C.M. Schroeder
  • Source: Electronics Letters, Volume 20, Issue 7, p. 304 –305
  • DOI:  10.1049/el:19840208
  • Type: Article
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  • p. 304 –305 (2)
    The letter reports the successful achievement of coating silica fibre at a rate of greater than 10 m/s. We draw 125 μm-diameter fibres from silica rods and preforms, and coated in-line with UV-curable material. All fibres were proof-tested at two different stress levels of 0.7 and 1.4 GN/m2 We also checked the transmission properties of the fibre. It is found that the optical properties of the fibre remain the same while the mechanical properties are comparable to those of the fibres coated at a low speed.
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Selectively doped n+ InP/n− GaInAs heterostructure prepared using chloride transport vapour-phase epitaxy
  • Author(s): M. Takikawa ; J. Komeno ; M. Ozeki
  • Source: Electronics Letters, Volume 20, Issue 7, p. 306 –307
  • DOI:  10.1049/el:19840209
  • Type: Article
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  • p. 306 –307 (2)
    A field-effect transistor with a 2 μm Au gate was fabricated on a selectively doped InP/GaInAs heterostructure grown using chloride transport vapour-phase epitaxy. Complete pinch-off was observed, and transconductance of 90 and 160 mS/mm were measured at 295 and 77 K, respectively. From analysis of the drain I/V characteristic, two-dimensional electron gas at the interface was revealed to be the dominant factor for the channel current. This is the first report of a successful preparation of an n+ InP/n− GaInAs heterostructure for the selectively doped field-effect transistor.
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Observations of amplitude scintillations on a low-elevation Earth-space path
  • Author(s): P.S.L. Lo ; O.P. Banjo ; E. Vilar
  • Source: Electronics Letters, Volume 20, Issue 7, p. 307 –308
  • DOI:  10.1049/el:19840210
  • Type: Article
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  • p. 307 –308 (2)
    Results of amplitude-scintillation measurements at 11 GHz on an 8.9° elevation path from an INTELSAT V satellite are presented and briefly compared with those obtained from OTS at 30° of elevation. The variability of the standard deviation of the process is illustrated and discussed in the context of the long-term distribution. Spectral density analysis reveals the familiar bandlimited noise type of spectrum with a 3 dB corner frequency of about 60 mHz.
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Stray-free switched-capacitor unit-delay circuit
  • Author(s): P. Gillingham
  • Source: Electronics Letters, Volume 20, Issue 7, p. 308 –310
  • DOI:  10.1049/el:19840211
  • Type: Article
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  • p. 308 –310 (3)
    A two-phase stray-insensitive switched-capacitor unit-delay circuit utilising only one operational amplifier is presented. The implementation of sampled analogue filters based on digital-filter architectures using this circuit as a building block is demonstrated. A final application of the unit delay, a switched-capacitor interpolator which effectively doubles the sampling frequency of the output of an analogue discrete-time system, is shown.
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