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Electronics Letters

Issue 9 • Date April 29 2010

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Displaying Results 1 - 25 of 43
  • In brief

    Page(s): 600
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (83 KB)  

    First Page of the Article
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  • Interview

    Page(s): 600
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    The feasibility of ultrafast digital communication links at THz frequencies has been demonstrated in the Letter `Wireless digital data transmission at 300 GHz?? on page 661. One of the co-authors, Dr Thomas Kleine-Ostmann from Physikalisch-Technische Bundesanstalt in Germany, tells us more. View full abstract»

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  • An attractive couple

    Page(s): 601
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (329 KB)  

    Summary form only given. A high frequency CMOS-MEMS filter, suitable for wireless communications, has been created by the coupling of two mechanical resonators. View full abstract»

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  • Tuning into terahertz

    Page(s): 602
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (305 KB)  

    Interdigitated photoconductive antennas have been engineered to reach even more of the THz spectrum for pulsed spectroscopy and imaging. One of the main sources of THz radiation, the interdigitated photoconductive antenna, can now be 'tuned' to THz frequencies that were previously difficult to reach. Researchers at the Ecole Normale Superieure in France found that changing the spacing between the electrodes in the antenna's structure enables the emission spectrum to be centred at a chosen frequency; a property that will be useful for spectroscopy and imaging, where access to particular parts of the THz spectrum is needed. View full abstract»

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  • Effects of thermal annealing condition on N-incorporated ZnO films in FBAR devices

    Page(s): 605 - 606
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (258 KB)  

    A new approach to fabricate the film bulk acoustic wave resonator (FBAR) devices is presented that employs high-quality piezoelectric ZnO films, particularly sputter-deposited in a mixture of N2O and Ar gases as the reactive and sputtering gases, respectively. Various thermal annealing treatments were performed on the deposited ZnO films and their effects on the resonance characteristics of the FBAR devices were investigated. With a process optimisation, the FBAR devices could be fabricated to have excellent resonance characteristics in terms of return loss. View full abstract»

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  • Broad dual-band PIFA using self-complementary structure for DVB-H applications

    Page(s): 606 - 608
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (635 KB)  

    A dual-band (UHF: 470-862 MHz, L: 1452-1492 MHz) digital video broadcasting-handheld (DVB-H) antenna is presented. The proposed antenna is composed of a planar inverted F-shape antenna (PIFA) with a self-complementary structure for the broadband performance. The measured operation bandwidth of the antenna (VSWR < 4) is 500 MHz (370-870 MHz) at UHF band and 220 MHz (1300-1520 MHz) at L-band. The proposed antenna has an approximately omnidirectional radiation pattern and sufficient gain (average peak gain; -1.74 dBi over 470-862 MHz) for DVB-H applications. View full abstract»

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  • Dielectric spiral resonators

    Page(s): 608 - 609
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (257 KB)  

    The possibility of constructing a resonator with a dielectric spiral inner is discussed. The modelling conducted shows that the mode related to the ceramic quarter-wave resonators also exists within a dielectric spiral, the properties of which are strongly dependent on the thickness and the number of turns of the spiral. The low filling factors associated with the resonant mode explains the high quality factors possessed by some of the spirals studied. View full abstract»

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  • Dual circular polarisation microstrip array antenna for WLAN/WiMAX applications

    Page(s): 609 - 611
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (327 KB)  

    A planar 2 ?? 2 microstrip array antenna with dual circular polarisation (CP) is presented. This array can be reconfigured and operated with either the right-handed (RH) or left-handed (LH) CP by controlling the input state of the branch-line coupler. A prototype has been fabricated with a 0.4 mm-thick FR4 top layer for radiating elements and a 0.8 mm-thick FR4 bottom layer for a feeding network, where a 5 mm air spacing is inserted between them. Wide operating frequency ranges for RHCP and LHCP states can be achieved at about 1.55 GHz and 1.54 GHz, respectively. Good radiation properties across the operating band are also obtained so that the proposed array antenna is suitable for WLAN and WiMAX applications. View full abstract»

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  • Frequency tunable terahertz interdigitated photoconductive antennas

    Page(s): 611 - 613
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (186 KB)  

    Frequency tunable terahertz (THz) interdigitated photoconductive antennas (PCAs) are realised by adjusting electrode spacing. An interdigitated geometry allows fabrication of PCAs with small gaps and large surface area for optical excitation. The pulsed electric field and emission spectra are measured using THz-time domain spectroscopy (TDS). It is observed that the peak frequency of the emitted spectra is shifted to higher frequencies (from 0.73 to 1.33 THz) as the electrode gap decreases (from 20 to 2 m). Measurements are in good agreement when compared to Drude-Lorentz simulations that include the interdigitated capacitance and gap size. The simulations highlight that as the electrode spacing is reduced, faster space-charge screening of the bias field occurs, leading to the higher frequency emission. As a result, the frequency response of an interdigitated PCA can be easily designed with an appropriate electrode spacing geometry. View full abstract»

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  • Planar antenna for continuous beam scanning and broadside radiation by selective surface wave suppression

    Page(s): 613 - 614
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (333 KB)  

    A printed leaky-wave antenna (LWA) based on a grating of concentric annular microstrip rings fed by a non-directive TM0 surface-wave launcher (SWL) is presented for two-sided continuous beam scanning and broadside radiation. By appropriate selection of the grating periodicity TE field distributions can be suppressed over a large bandwidth ensuring efficient TM0 leakage and radiation into the far field. Measured results demonstrate a pencil beam at broadside with a 3 dB beamwidth less than 6 at 17.9 GHz. The presented LWA may be useful for radar and surveillance systems where continuous beam scanning through broadside is desired. View full abstract»

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  • On-chip pulse based parallel neural circuits for object-tracking system

    Page(s): 614 - 616
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    A scheme of pulse based neural circuits for object tracking is proposed. Different from the conventional frame-based methodology, the proposed design utilises parallel arrays of circuits to extract pixels with significant temporal contrast, which are indicators of moving objects. It can be implemented on an FPGA chip in full parallelism and improves the tracking performance dramatically. Moreover, its integrate-and-fire neural model can cluster concave data sets. Experimental results show that the proposed scheme outperforms conventional methods. View full abstract»

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  • Analogue wavelet transform with single biquad stage per scale

    Page(s): 616 - 618
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (214 KB)  

    A new approach to obtain the wavelet transform with easily constructed analogue circuits is presented. It is shown that the impulse response of a bandpass biquad filter satisfies the conditions to be considered a mother wavelet. Using this, an integrated circuit performing the wavelet transform at 16 scales along eight octaves has been designed. The design has CMOS transistors working in the subthreshold region with a total power consumption of 650 nW. On-chip measurements are reported. View full abstract»

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  • Low-power L2 cache design for multi-core processors

    Page(s): 618 - 620
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (131 KB)  

    A low-power set-associative L2 cache design for a multi-core processor is proposed. Since this way-predicting L2 cache (WP-L2) predicts a destination way and accesses only the predicted way, it consumes less energy than a conventional set-associative L2 cache. Exploiting access patterns of an L2 cache, WP-L2 is based on two prediction logics; a look-ahead buffer (LAB) predicts the next sequential cache block and a way-affinity table (WAT) records the way number of the previous L2 cache access. Combining the logics, WP-L2 predicts correct ways for about 83% of L2 cache accesses and reduces about 22% of access latency and 44% of energy consumption compared to the conventional eight-way set-associative L2 cache. View full abstract»

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  • Merged capacitor switching based SAR ADC with highest switching energy-efficiency

    Page(s): 620 - 621
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    A modified merged capacitor switching (MCS) scheme is proposed for the successive approximation register (SAR) analogue-to-digital converter (ADC). The conventional MCS technique previously applied to a pipelined ADC improves signal processing speed and, with use in the SAR ADC, this scheme achieves lowest switching energy among existing switching schemes. The MCS scheme achieves 93.4% less switching energy as compared to the conventional architecture. View full abstract»

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  • Magnetic hand motion tracking system for human-machine interaction

    Page(s): 621 - 623
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (187 KB)  

    A magnetic hand motion tracking system for a variety of applications requiring human-machine interaction is presented. Small permanent magnets are fixed on fingernails as signal sources. A series of magnetic sensors on a wristband measure magnetic signals related to the movements of the fingertips. The measured data are transmitted to the application wirelessly. A hand geometric model and a least-square source localisation algorithm are utilised to calculate the hand postures. This system does not require wire connections and can be used conveniently and unobstructively. View full abstract»

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  • Experimental demonstration of directive pulsed wavefront generation in reverberation chambers

    Page(s): 623 - 624
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    The first experimental demonstration of coherent directive and polarised wave-front generation within a reverberation chamber is presented. This feature is possible with the use of a time reversal electromagnetic chamber, a concept previously introduced by the present authors which mainly relies on the use of time-reversal techniques in a highly reverberating medium. The rationale for developing such a system is to provide the control of a field distribution in time and space without any mechanical movement of either sources or an equipment under test while preserving the high-intensity field levels achieved with reverberation chambers. View full abstract»

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  • Method for unsupervised change detection in satellite images

    Page(s): 624 - 626
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (154 KB)  

    A Gaussian mixture model (GMM) and Bayesian inferencing (BI) based unsupervised change detection method in satellite images is presented. The data distribution of the difference image, which is computed from satellite images of the same scene acquired at different time instances, is modelled by using GMM. The components of the overall GMM are separated into two classes to model the data distributions of changed and unchanged pixels. The weights of the components in each class are used to estimate the a priori probability of each corresponding class. The final change detection is achieved by applying BI to classify each pixel of the difference image into one or two classes. View full abstract»

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  • Adaptive reconstruction scheme using neighbour pixels in PDWZ coding

    Page(s): 626 - 628
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (145 KB)  

    Distributed video coding (DVC) is an emerging video coding technology that utilises information theory for distributed sources to build a very simple encoder. In the DVC codec, the reconstruction function for the Wyner-Ziv (WZ) frame is one of the most important modules for improving the quality of the decoded image. An efficient reconstruction algorithm is proposed that uses neighbour pixel information. Simulation results show that the proposed algorithm improves the quality of the decoded image without an increase in the bit rate. View full abstract»

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  • Depth-preserving DIBR based on disparity map over T-DMB

    Page(s): 628 - 629
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (282 KB)  

    An efficient depth-image-based-rendering (DIBR) method is presented based on a disparity map over terrestrial-digital multimedia broadcasting (T-DMB). Experimental results show that the proposed method can create depth-preserving auto-stereoscopic images in mobile broadcasting environments with limited bandwidth. View full abstract»

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  • Initial codebook method of vector quantisation in Hadamard domain

    Page(s): 630 - 631
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (71 KB)  

    To deal with the problem that the initialisation method based on random selection may provide a suboptimal codebook of vector quantisation (VQ); an improved method is proposed. In the proposed method, Hadamard transform is performed on training vectors, and then the transformed vectors are sorted according to their first elements. The ordered transformed vectors are partitioned into groups. The initial codebook is composed of the mid vector of each ordered group. This method has a better performance and can be used as the initialisation method of VQ to improve and speed up codebook design. View full abstract»

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  • Photometric recovery of Apollo metric imagery with Lunar-Lambertian reflectance

    Page(s): 631 - 633
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (197 KB)  

    The scene radiance of the lunar surface, the reflectance of which depends on the topographical configuration is reconstructed from Apollo orbital imagery. The pixel value is determined by the camera response of sensor exposure which is proportional to scene radiance, lunar reflectance and exposure time. Based on the Lunar-Lambertian reflectance model, the point-wise reflectance is pre-calculated from the Apollo metadata and digital elevation models. The surface radiance, exposure time and camera response are estimated by the maximum likelihood method for sensor exposure which follows a continuous Poisson distribution with the mean of surface radiance. An alternating parameter scheme is proposed to determine the one family of parameters from the others. The photometric recovery of ortho-images derived from Apollo 15 metric camera imagery is presented to show the validity of the proposed method. View full abstract»

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  • Bubble check: a simplified algorithm for elementary check node processing in extended min-sum non-binary LDPC decoders

    Page(s): 633 - 634
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (139 KB)  

    A simplified algorithm for the check node processing of extended min-sum non-binary LDPC decoders is proposed. This novel technique, named bubble check, can reduce the number of compare operations by a factor of three at the elementary check node level. As this significant complexity reduction is achieved without any performance loss, this technique becomes highly attractive for hardware implementation. View full abstract»

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  • Nonlinear HBT table-based model including low-frequency noise effects

    Page(s): 635 - 636
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (286 KB)  

    A nonlinear HBT table-based model is presented in which low-frequency (LF) noise effects are incorporated, thus allowing for precise oscillator design. The model uses four table-based nonlinear functions: Ic, Qc, Vbe and Qb, and takes into account temperature and noise behaviour. This approach is able to predict the LF noise behaviour under both static and dynamic conditions by using cyclostationary noise sources. HBT-based oscillators have been designed using this model, and very good predictions have been obtained for the oscillation frequency, the output power and the phase noise. View full abstract»

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  • Transmission performance enhancement for EIN limited 2.5 Gbit/s RSOA-based WDM-PON by using dispersion management

    Page(s): 636 - 638
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    2.5 Gbit/s loop-back wavelength division multiplexing-passive optical networks (WDM-PON) based on reflective semiconductor optical amplifiers (RSOA) is demonstrated, which fully supports 100 GHz-spaced WDM channels. The use of dispersion management for both up- and downstream transmission removes the error floor owing to the chromatic dispersion induced excess intensity noise. It has also been experimentally confirmed that both pre- and post-dispersion compensating schemes are effective ways to suppress the intensity noise. View full abstract»

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  • Batch fabricated long throw bi-stable electromagnetic micro-actuator

    Page(s): 638 - 639
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (405 KB)  

    A long throw bi-stable electromagnetic micro-actuator is presented. Its configuration was easy to be batch fabricated. According to the experiment results, when the actuator was applied with a 5 V voltage pulse, the bi-stable switch was realised and the output displacement was larger than 150 m. Its overall size is 6 ?? 6 ?? 3 mm. The device structure, principle and fabrication method are also presented. 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