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Electronics Letters

Issue 10 • Date May 13 2010

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Displaying Results 1 - 25 of 44
  • In brief

    Page(s): 666
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    First Page of the Article
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  • Interview

    Page(s): 666
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (118 KB)  

    Dr Xiaobin Yuan from the Microelectronics Division of IBM and author of the Letter 'Transistor mismatch in 32 nm high-k metal-gate process' on page 708 tells us more about his research into advanced process technologies. View full abstract»

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  • Strength in numbers

    Page(s): 667
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (174 KB)  

    The first coherent vertical cavity surface-emitting laser (VCSEL) array with the in-phase mode using a simple fabrication process has been demonstrated at the University of Illinois at Urbana-Champaign in the USA. The 2 × 2 VCSEL array was made using conventional fabrication processes that are already in use to manufacture millions of VCSELs, and photonic crystal coupling was used to control the cavity loss and achieve a stable beam mode. "An important advantage is the possibility to scale up the array size to coherently combine several tens to potentially thousands of VCSELs into a coherent array," said Professor Kent Choquette, Director of the Photonic Device Research Group. "Such high power low divergence laser arrays are of interest for optical pumping of solid state and/or fibre lasers at very specifi c emission wavelengths, as well as being directly used as high power laser sources for applications such as laser welding, LIDAR, and laser infrared illumination." View full abstract»

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  • A fluid approach to microwaves

    Page(s): 668
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (492 KB)  

    Collaborative researchers from the University of Cambridge in the UK and Technische Universitÿt Darmstadt (TUD) in Germany have signifi cantly increased the dielectric anisotropy of liquid crystals in the microwave range by adding minute amounts of carbon nanotubes. This result is a signifi cant step for the use of liquid crystals as a tunable material in a wide range of microwave devices at frequencies up to several THz. View full abstract»

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  • Planar multi-band monopole antenna with L-shaped parasitic strip for WiMAX application

    Page(s): 671 - 672
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (291 KB)  

    A multi-band design of a planar inverted L-shaped monopole antenna with an L-shaped parasitic strip for the WiMAX system is proposed. With the use of L-shaped monopole and parasitic strips, multi-resonant modes close to the 2.6/3.5/5.5 GHz bands are excited to meet the specifications of the WiMAX system (IEEE 802.16e). Also, obtained impedance bandwidth across the operating bands can reach about 270/1000/1250 MHz for the 2.6/3.5/5.5 GHz bands, respectively. With a nearly omnidirectional pattern in the xy-plane, measured peak gains and radiation efficiencies are about 3.7/3.1/4.8 dBi and 68/80/84% at the 2.6/3.5/ 5.5 GHz operating bands, respectively. View full abstract»

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  • Small square slot antenna with circular polarisation characteristics for WLAN/WiMAX applications

    Page(s): 672 - 673
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (338 KB)  

    A small square slot antenna with circular polarisation characteristics for WLAN/WiMAX applications is presented. The proposed antenna consists of a microstrip feed line and a ground plane with a novel slot configuration which provides usable circular polarisation characteristics on the WLAN/WiMAX frequency bands. By optimising the length of the feed line, the total bandwidth of the antenna is greatly improved. Moreover, the desired circular polarisation characteristics are obtained by adjusting the number of slot arms in the ground plane. The designed antenna has a small size of 30 ?? 30 ?? mm2. View full abstract»

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  • Spiraphase-type element with optimal transformation of switch impedances

    Page(s): 673 - 675
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    An electronically-reconfigurable spiraphase-type element based on a ring slot resonator is analysed. It is demonstrated with numerical simulation and experimental measurements that optimal transformation of the switch impedances is possible in this element. As a result, low loss of 0.38 dB is obtained for the one-bit element at the frequency of 11.55 GHz. View full abstract»

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  • Wideband cavity backed slot antenna for automotive monopulse radars

    Page(s): 675 - 677
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (195 KB)  

    A wideband cavity backed slot antenna is designed for automotive-borne monopulse radar applications. A rectangular slot is used to realise broad bandwidth; the slot is backed by a cavity, and the vertical walls of the cavity are implemented by discrete vias; and the slot is fed by a microstrip line. The proposed antenna is compact, robust, fully planar and easy to integrate. A two-element array is fabricated and tested. Measured input impedance is matched to 50 ?? within band [2.61 GHz, 3.44 GHz] (27.5% bandwidth); and monopulse beam-scanning is successfully demonstrated. View full abstract»

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  • Cognitive memory network

    Page(s): 677 - 678
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (237 KB)  

    A resistive memory network that has no crossover wiring is proposed to overcome the hardware limitations to size and functional complexity that is associated with conventional analogue neural networks. The proposed memory network is based on simple network cells that are arranged in a hierarchical modular architecture. Cognitive functionality of this network is demonstrated by an example of character recognition. The network is trained by an evolutionary process to completely recognise characters deformed by random noise, rotation, scaling and shifting. View full abstract»

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  • Development of capacitance measurement system for human serum albumin detection

    Page(s): 678 - 680
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (257 KB)  

    The use of interdigitated electrodes and binding with Cibacron blue F3GA by self-assembly technology, which has high affinity for human serum albumin (HSA), and serves as a receptor for HSA detection, is reported. In preliminary tests, the interdigitated chip measured the impedance of HSA by electrochemical impedance spectroscopy and this result indicated the characteristic frequency of impedance change below 1.1 kHz. However, a portable capacitance measurement system made using a standard operational amplifier circuit and AC excitation was applied at 1 kHz. The detection result showed a significant linear correlation between HSA concentration (0.1 to 1 mg/ml) and output voltage. The regression equation was Y 17.91 323.72X with R2 = 0.999. This reported study has successfully demonstrated that the capacitive sensor has great potential for applications in HSA detection. View full abstract»

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  • Multiscale principal contour direction for varying lighting face recognition

    Page(s): 680 - 682
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (236 KB)  

    Proposed is a new type of image feature for varying lighting face recognition, namely, multiscale principal contour direction (MPCD). It can capture `true` neighbourhood contour direction information and is robust to different illumination conditions. In addition, MPCD is constructed for extracting illumination invariant by applying the non-subsampled contourlet transform (NSCT) to multiscale contour analysis. To evaluate its performance, a series of experiments are performed on two well-known illumination databases (i.e. Yale B and CMU PIE), showing the efficacy of the method. View full abstract»

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  • Regularisation of eigenfeatures by extrapolation of scatter-matrix in face-recognition problem

    Page(s): 682 - 683
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (91 KB)  

    The proposed face recognition algorithm regularises the within-class scatter matrix by extrapolating its eigenvalues. This way both the range space and the null space information of the within-class scatter matrix is utilised. The results are promising when the algorithm is experimented on face recognition datasets and compared with several other methods. View full abstract»

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  • Detector for signals in generalised normal-Laplace distributed noise

    Page(s): 683 - 684
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (211 KB)  

    A novel near-optimal receiver is introduced for the detection of signals in noise modelled with a new probability distribution called a generalised normal-Laplace (GNL) distribution. The near-optimal detector is based on the approximation of GNL probability density function (PDF) while the optimum detector uses the PDF obtained by the Fourier inversion of the characteristic function. The performance of the near-optimal receiver is shown to be very close to the optimum receiver. View full abstract»

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  • Load balancing for two-tier Chord system

    Page(s): 685 - 686
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (301 KB)  

    Compared to flat distributed hash table (DHT) systems, hierarchical DHT systems can use some powerful and stable peers (called superpeers) to achieve efficient look-up under churn. Several hierarchical DHT systems have been proposed so far. However, a crucial problem faced by all these systems is the load imbalance among superpeers. Proposed is a novel load balancing algorithm to efficiently solve this problem in a two-tier Chord system. Analysis and simulation results show that the algorithm can balance the load among superpeers in proportion to their capacity. View full abstract»

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  • Frequency stability measurements of ultrastable BVA resonators and oscillators

    Page(s): 686 - 688
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (239 KB)  

    The performances of instruments developed for the measurement of 5 MHz ultra-stable resonators, before and after being integrated in an oscillator, are presented. The chosen resonator has an estimated stability of several 10-14. The intrinsic noise floor of these benches are about 7 to 9.5 10-15. View full abstract»

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  • Compact dual-band power divider with single allpass coupled lines sections

    Page(s): 688 - 689
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (271 KB)  

    A compact dual-band power divider is presented. An allpass coupled lines section is used to realise the necessary impedance transformation at two selected frequencies. The design procedure, limitations and examples are provided first. To implement the design in microstrip, stepped-impedance coupled lines are used without changing the circuit size to compensate for the different even- and odd-mode phase velocities. View full abstract»

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  • Compact microstrip lowpass filter with ultra-wide stopband

    Page(s): 689 - 691
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    A compact microstrip lowpass filter with an ultra-wide stopband is proposed. To achieve wide stopband suppression and compact size, both symmetrically loaded resonant patches and meander transmission line are adopted. A demonstration filter with 3 dB cutoff frequency at 1.3 GHz has been designed, fabricated and measured. The proposed filter also exhibits a very wide stopband of 152 , and is able to suppress the eleventh-harmonic response together with a small size of 0.12 g ?? 0.071??g, where ??g is the guided wavelength at 1.3 GHz. View full abstract»

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  • Quad-band bandpass filter based on dual-plane microstrip/DGS slot structure

    Page(s): 691 - 692
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    An approach for designing a quad-band bandpass filter is presented. The dual-plane structure composed of both a microstrip and a defected ground structure (DGS) slot is employed to obtain quad-frequency responses. The slot, with interdigital shape in the DGS, is designed to obtain dual-frequency responses and transmission zeros are introduced to split both passbands into two. The equivalent-circuit model is derived for the filter. A filter with four passbands centring at 1.74, 2.09, 2.75 and 3.14 GHz is shown with a stopband attenuation greater than 20 dB over the frequency range from 3.38 to 7.70 GHz. View full abstract»

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  • UWB bandpass filter with notched band using DSRR

    Page(s): 692 - 693
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (358 KB)  

    A topology of a compact planar microstrip filter with a notched band is introduced, which employs a split-ring resonator defected ground structure (DSRR). Folded short-circuited stubs are used to realise the bandpass filter with good selectivity and out-of-band characteristics. By employing a split-ring resonator defected ground structure, a narrow notched band was introduced to reject the undesired wireless local-area network (WLAN) radio signals. The measured insertion loss is less than 1.6 dB, the return loss is more than 13 dB, and the variation of group delay is less than 0.5 ns throughout most of the two passbands. The width of the narrow notched band is about 1 GHz and the attenuation is more than 25 dB at the centre frequency of 5.4 GHz. View full abstract»

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  • Dielectric anisotropy of nematic liquid crystals loaded with carbon nanotubes in microwave range

    Page(s): 693 - 695
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (163 KB)  

    Liquid crystals are attractive materials for microwave applications as tunable dielectrics owing to low losses and high anisotropy of dielectric properties. The possibility of further enhancing their dielectric anisotropy is studied by loading with highly polarisable and anisotropic rods-carbon nanotubes at various concentrations. The studies are performed using two different methods, one in the range 1-4 GHz and the other at 30 GHz. More than two times increase of microwave dielectric anisotropy in liquid crystals is reported when loaded with 0.01%wt of carbon nanotubes, which is a metastable suspension and 28% increase in an equilibrated suspension. The stability of the LC-CNT composites is discussed. View full abstract»

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  • Improved thermal model for optical fibre coating owing to small bending diameter and high power signals

    Page(s): 695 - 697
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (147 KB)  

    Long-term optical network reliability is highly dependent on the fibre quality. However, poor handling or installation can impose bendings in the optical fibres, leading to a significant increase in link losses, which results in fibre coating degradation owing to heating occurring in the presence of high power signals propagation. Presented, for the first time, is an accurate thermal model for optical fibres under tight bending and high power conditions. View full abstract»

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  • InGaAsP/InP optical digital-to-analogue converter for 40 Gbit/s, 3-bit operation

    Page(s): 697 - 698
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (433 KB)  

    A 40 Gbit/s, 3-bit operation of a semiconductor optical digital-to-analogue converter, consisting of inputand output-side 1 ?? 3 MMI couplers and 1and 2-bit optical delay lines based on InGaAsP/InP materials, is presented. Splitting the ratio of an input-side 1 ?? 3 MMI coupler is designed to have almost equal signal quality in each output level under the extinction ratio of the input signal of 23 dB. Moreover, the difference of two adjacent delay lines is intentionally different to obtain an arbitrary combination of optical phase difference. An output signal with 7-level amplitude under the same phase bias condition is achieved successfully for the first time. View full abstract»

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  • Laser phase noise induced error-rate floors in differential n-level phase-shift-keying coherent receivers

    Page(s): 698 - 700
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (111 KB)  

    A simple and illustrative analytical model for the phase noise influence in differential n-level phase shift keying (nPSK) systems is presented. Results for the phase noise sensitivity are given for a dual polarisation system configuration with basic baud-rate of 25 GS/s. Results emphasise the need for highly phase stable optical signal sources in higher constellation configurations as needed for total system capacities of 400 Gbit/s or more. Classical distributed feedback laser diodes with linewidth of 200 kHz-10 MHz are not feasible beyond the order of 200 Gbit/s capacity. 2n-level circular quadrature amplitude modulated (2nQAM) systems may increase the capacity by 50 Gbit/s compared to nPSK with no added phase noise penalty. View full abstract»

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  • Phase noise characteristics of all-optical single sideband frequency upconverter for radio-over-fibre applications

    Page(s): 700 - 701
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (239 KB)  

    The phase noise characteristics of an all-optical single sideband frequency upconverter that uses an optical interleaver and a semiconductor optical amplifier are experimentally investigated. While the phase noise characteristic of the upconverter is limited by that of the LO signal source, it becomes degraded owing to the path imbalance of the two optical signal paths. Compensation for the path imbalance by a delay line produces an optimised phase noise of the upconverted RF signal of approximately -98 dBc/Hz at the offset frequency of 10 kHz. View full abstract»

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  • Running-code optical CDMA at 2 x 10 Gbit/s and 40 Gbit/s

    Page(s): 701 - 703
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (342 KB)  

    A continuously running-code optical CDMA system useful for secure communications is reported. The system utilises acousto-optic modulator-based pulse shapers as spectral phase en-/decoding devices, which are capable of microsecond-scale code sequence refresh rates. The codes are generated on-the-fly by a stream cipher. Transmit/ receive code synchronisation is independent of the data stream, allowing for a flexible data rate. Two multiplexed 10 Gbit/s channels and a single 40 Gbit/s channel are demonstrated. View full abstract»

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Aims & Scope

Electronics Letters is internationally renowned for its rapid communication of new developments and emerging topics across the broad and interdisciplinary field of modern electronics and electrical engineering.

Full Aims & Scope

Meet Our Editors

Editors-in-Chief

Professor Chris Toumazou
Director of the Biomedical Institute
Imperial College, London, UK

Professor Ian White
Head of Photonics Research
University of Cambridge, UK