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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 29, Issue 19, 16 September 1993

Volumes & issues:

Volume 29, Issue 19

16 September 1993

Time-interleaved oversampling convertors
  • Author(s): R. Khoini-Poorfard  and  D.A. Johns
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1673 –1674
  • DOI:  10.1049/el:19931112
  • Type: Article
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  • p. 1673 –1674 (2)
    A new architecture is proposed which exploits the time-interleaving concept to increase the oversampling ratio in delta-sigma modulators. It is shown that the effective oversampling ratio is increased by a factor M through the use of M interconnected modulators. Although a high speed sample-and-hold circuit is still required for an analogue-to-digital convertor, speed constraints are significantly reduced for the majority of analogue parts such as loop filters, A/D and D/A blocks.
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Optimal design of contiguous-band output multiplexers (COMUX)
  • Author(s): G. Tanne ; S. Toutain ; J.F. Favennec ; P. Jarry ; C. Boschet
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1674 –1675
  • DOI:  10.1049/el:19931113
  • Type: Article
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  • p. 1674 –1675 (2)
    A general multiplexer design procedure without dummy channels is described. The formulas are applied to the optimal design of practical contiguous or non-contiguous band multiplexers consisting of multicavity filters distributed along a waveguide manifold. All design parameters can be directly optimised. An example of a practical 12 channel, 12 GHz contiguous band multiplexer is presented.
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Signal transform covariant to scale changes
Interfacial polarisation in Al-Y2O3-SiO2-Si capacitor
Combined-field integral equation
  • Author(s): A. Helaly  and  H.M. Fahmy
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1678 –1679
  • DOI:  10.1049/el:19931116
  • Type: Article
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  • p. 1678 –1679 (2)
    The combined-field integral equation (CFIE) is a linear combination of the H-field and the E-field integral equations. Previously, the weighting parameter of the E-field equation in the CFIE had been assumed constant along the generating curve of the body of revolution. However, in the Letter it is shown that the weighting parameter can take a variable distribution along the generating curve or on a part of it only. In the latter case, a reduction in the computational time of 40–50% is achieved.
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Multimode chamber excited by an array of antennas
Improved design of CMOS multiple-input Muller-C-elements
Large nonlinear optical effect in an InGaAs/InAlAs multiquantum well waveguide
  • Author(s): T. Kanetake ; H. Inoue ; S. Tanaka ; K. Ishida
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1682 –1684
  • DOI:  10.1049/el:19931119
  • Type: Article
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  • p. 1682 –1684 (3)
    All-optical refractive nonlinearity in a passive InGaAs/InAlAs multiquantum well waveguide is evaluated for TE and TM modes at 1.55 μm wavelength and room temperature. A quarter wavelength change in the optical path length is observed at an input pump light power of 6.5 mW for 1.47 μm wavelength in a 960 μm long device. Nonlinear refractive index n2 is evaluated to be 1.2×10−6 and −0.5×10.6 cm2/W for the TE and the TM modes, respectively.
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Surface-relief type Bragg grating reflector fabricated after overcladding removal
  • Author(s): M. Ishii ; Y. Hibino ; A. Sugita ; T. Tamamura
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1684 –1685
  • DOI:  10.1049/el:19931120
  • Type: Article
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  • p. 1684 –1685 (2)
    A novel silica-based Bragg grating reflector on Si substrate is described. The reflector is formed on a core whose overcladding layer is removed by RIE until it is level with the core surface. The reflector which comprises a rectangular relief type grating only 1.6 mm long has the advantages of a highly controllable Bragg wavelength and a high reflectivity of 76% for the TE mode.
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α-factor improvements in high-speed p-doped In0.35Ga0.65As/GaAs MQW lasers
  • Author(s): A. Schönfelder ; S. Weisser ; J.D. Ralston ; J. Rosenzweig
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1685 –1686
  • DOI:  10.1049/el:19931121
  • Type: Article
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  • p. 1685 –1686 (2)
    The authors investigate experimentally for the first time the improvements in the linewidth enhancement factor, α, resulting from simultaneous addition of strain and p-doping in high-speed GaAs-based multiquantum well lasers. The α factor is determined from measured changes in both gain and refractive index as a function of CW bias current, yielding α 3.1 and 1.4 at the threshold lasing wavelength for unstrained GaAs/Al0.25Ga0.75As and p-doped strained In0.35Ga0.65As/GaAs devices, respectively.
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Er-fibre lasers: suppression of spatial hole burning by internal modulation
Experimental evidence for hole transport limited intensity modulation response in quantum well lasers
GaInP/AlGaInP index waveguide-type visible laser diodes with dry-etched mesa stripes
  • Author(s): T. Yoshikawa ; Y. Sugimoto ; H. Hotta ; K. Tada ; K. Kobayashi ; S. Kohmoto ; K. Asakawa ; H. Yoshii ; H. Kawano
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1690 –1691
  • DOI:  10.1049/el:19931124
  • Type: Article
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  • p. 1690 –1691 (2)
    GaInP/AlGaInP index waveguide-type visible-light laser diodes with dry-etched mesa stripes have been fabricated by Cl2-reactive ion beam etching for the first time. The AlGaInP cladding layer, which is normally very difficult to dry etch due to problems with Al oxidation and the low volatility of In and its reaction products, was etched smoothly with high depth accuracy. The etched mesa stripes were buried by metal organic vapour-phase epitaxy with-out crystal discontinuity at the regrown surface. The threshold current under room-temperature pulsed operation is 35 mA (L = 300 μm), which is almost the same value as that for wet-etched lasers.
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High-temperature (130°C) CW operation of 1.53 μm InGaAsP ridge-waveguide lasers using strained quaternary quantum wells
Room temperature continuous wave operation of red vertical cavity surface emitting laser diodes
7.4 Gbit/s monolithically integrated GaAs/AlGaAs laser diode-laser driver structure
Strained multiquantum-well corrugation-pitch-modulated distributed feedback laser with ultranarrow (3.6 kHz) spectral linewidth
  • Author(s): M. Okai ; M. Suzuki ; T. Taniwatari
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1696 –1697
  • DOI:  10.1049/el:19931128
  • Type: Article
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  • p. 1696 –1697 (2)
    Introducing a 1% compressive strained multiquantum-well (MQW) active layer into a corrugation-pitch-modulated distributed feedback (CPM-DFB) laser reduces the linewidth floor (residual linewidth for extrapolated infinite output power) to 2 kHz and results in a linewidth-power product of 140 kHz mW. Strained MQW CPM-DFB lasers produced a 55 mW output with a spectral linewidth of only 3.6 kHz.
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Miniaturised L-band MIC LNA design
  • Author(s): E. Bayar  and  A.H. Aghvami
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1698 –1699
  • DOI:  10.1049/el:19931129
  • Type: Article
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  • p. 1698 –1699 (2)
    A design technique for LNA size miniaturisation is described which does not compromise electrical performance. The method has been applied to the design of an L-band LNA and results in a measured noise figure of 0.25 dB and 15 dB associated gain. The circuit it realised in MIC technology with a total surface area of less than 4.8 × 8.8 mm2. The reduced size allows the LNA to be cascaded with MMIC gain blocks with little or no volume impact and considerably improved electrical performance compared with a complete MMIC solution.
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Planar MESFET transmission wave amplifier
  • Author(s): T. Mader ; J. Schoenberg ; L. Harmon ; Z.B. Popović
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1699 –1701
  • DOI:  10.1049/el:19931130
  • Type: Article
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  • p. 1699 –1701 (3)
    The authors present a quasioptical power combining transmission amplifier for increasing the power level available from solid-state circuits. Receiving and transmitting arrays of patch antennas, input/output isolation, MESFETs, bias and matching circuitry are contained on a single substrate, making monolithic millimetre-wave integration possible. The flexibility of selecting input polarisation with respect to the output while maintaining amplifier stability is demonstrated. A 24-MESFET patch antenna amplifier array is presented.
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Extended backpropagation algorithm
Novel technique to combine BWS and FWS classifiers
  • Author(s): K.P. Lam  and  E. Home
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1702 –1704
  • DOI:  10.1049/el:19931132
  • Type: Article
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  • p. 1702 –1704 (3)
    A novel approach to combining the binary weighted and frequency weighted schemes (BWS and FWS) for pattern classification is described. The method presented employs a well established statistical procedure and offers good performance. The principal advantages of the technique are that only a single layer is required and it avoids the serious problem of choosing optimal values for the zero-frequency components which occur in the FWS. Preliminary experiments demonstrate that the choice of operational parameters required is straightforward. Furthermore, the technique is intrinsically parallel and lends itself naturally to parallel implementation.
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Design consideration of singlemode interconnectable star coupler
Fast wavelength detection technique for multi-wavelength photonic packet networks
Influence of simulated Brillouin scattering on nonlinear distortion in SCM video transmission
Multichannel frequency conversion experiment using fibre four-wave mixing
  • Author(s): K. Inoue ; T. Hasegawa ; K. Oda ; H. Toba
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1708 –1710
  • DOI:  10.1049/el:19931136
  • Type: Article
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  • p. 1708 –1710 (3)
    Multichannel frequency conversion is demonstrated using fourwave mixing. A polarisation independent configuration is employed, by which polarisation control for each signal is not necessary. By setting the pump light frequency at the zero-dispersion wavelength of the fibre, three FSK modulated signals with a frequency spacing of 70 GHz are simultaneously converted with an equal efficiency of −27.5dB. Bit error rate measurements confirm the feasibility of this conversion scheme.
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Nonlinear switching in InGaAsP laser amplifier directional couplers biased at transparency
Suppression of soliton interactions by phase modulation
2.5 ps soliton pulse generation at 15 GHz with monolithically integrated MQW-DFBLD/MQW-EA modulator and dispersion decreasing fibre
Ultrahigh-speed phaselocked-loop-type clock recovery circuit using a travelling-wave laser diode amplifier as a 50 GHz phase detector
  • Author(s): S. Kawanishi ; H. Takara ; M. Saruwatari ; T. Kitoh
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1714 –1716
  • DOI:  10.1049/el:19931140
  • Type: Article
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  • p. 1714 –1716 (3)
    Successful operation of a phaselocked loop is demonstrated using travelling-wave laser-diode amplifier as a 50 GHz phase detector. Optical gain modulation in the laser diode amplifier and an optical clock multiplication technique using a silica-based guided-wave optical circuit are used to achieve the extremely highspeed operation. Also discussed is the possibility of more than 100 GHz operation.
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Wavelength conversion of high speed data signals
Linear optical path modulation with λ/200 accuracy using a fibre stretcher
Novel mid-infrared LED as a source for optical fibre gas sensing
Less than 3 pA/√Hz over 1–800 MHz noise current spectral density optical receiver for SCM-CATV systems
21 Gbits/s/cm2 throughput density two-dimensional array optical interconnection construction
  • Author(s): T. Kato ; F. Yuuki ; K. Tanaka ; H. Tanaka ; H. Masuda ; T. Tanoue ; A. Oishi ; K. Ito ; K. Murakami ; T. Teraoka
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1722 –1723
  • DOI:  10.1049/el:19931145
  • Type: Article
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  • p. 1722 –1723 (2)
    A new two-dimensional array optical interconnection construction is developed for the board-to-board level. A high throughput density of 21 Gbit/s/cm2 over the electric coaxial cable limit is achieved by the direct hybridisation of an 8 × 2-channel LD/PD array onto the transmitter/receiver IC and surface-mount packaging of a microlens array and a fibre-connector receptacle.
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High elevation angle propagation results, applied to a statistical model and an enhanced empirical model
  • Author(s): M.A.N. Parks ; B.G. Evans ; G. Butt
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1723 –1725
  • DOI:  10.1049/el:19931146
  • Type: Article
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  • p. 1723 –1725 (3)
    The results of a recent narrowband propagation experiment at high elevation angles have been further analysed to determine fit coefficients for the model proposed by Lutz et al. Results for the suburban and wooded environmental categories for elevation angles greater than 60° are reported. An empirical model for L and S bands covering elevation angles from 20 to 80° has been developed. The model combines the empirical roadside shadowing model, and the empirical fading model derived from the results of a narrowband propagation campaign, and improves the existing CCIR model.
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Effect of base dopants on the bias stress stability of AlGaAs/GaAs HBTs
  • Author(s): T. Ahmad ; A.A. Rezazadeh ; S.S. Gill
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1725 –1726
  • DOI:  10.1049/el:19931147
  • Type: Article
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  • p. 1725 –1726 (2)
    The effect of three base dopants C, Be and Zn on the bias stress stability of npn AlGaAs/GaAs HBTs has been investigated for the first time. In this study 3 × 30μm2 HBTs were fabricated under identical process technology, emitter-base geometry and layout design. Following 24 h of identical bias stress, it is found that both Be- and Zn-doped devices exhibited current gain degradation as high as 68 and 57%, respectively, compared with only 7% for the C-doped device. The superior bias stress stability of C-doped HBTs is demonstrated.
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Observation of new vibronic luminescence band in semiconducting diamond
High temperature superconductor lumped element resonator
  • Author(s): M.J. Lancaster ; J.C. Li ; A. Porch ; N.G. Chew
  • Source: Electronics Letters, Volume 29, Issue 19, p. 1728 –1729
  • DOI:  10.1049/el:19931149
  • Type: Article
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  • p. 1728 –1729 (2)
    The authors have studied a high temperature superconducting (HTS) lumped element resonator consisting of an inductance and capacitance in parallel. It has a low power unloaded quality factor Qo in excess of 9000 at 5.7GHz and 1K. The resonator is just over 1 mm square significantly smaller than any other device with comparable Q at this centre frequency. The authors also investigate the implementation of the resonator in a bandstop filter.
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Elimination of all grating lobes in ultrasonic synthetic focusing using a linear array
Erratum: Optical short pulse generation by double gate operation of tandem connected electroabsorption modulators driven by sinusoidal voltages
Erratum: Level, downhill and uphill walking identification using neural networks

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