Showing papers in "Electronics Letters in 2009"
TL;DR: In this article, a SPICE macromodel is described which simulates the electrical behavior of the recently discovered thin-film titanium dioxide (TiO 2 ) memristors.
Abstract: A SPICE macromodel is described which simulates the electrical behaviour of the recently discovered thin-film titanium dioxide (TiO 2 ) memristors. The macromodel allows for fast simulation of circuits that include memristors. The accuracy of the macromodel is demonstrated by comparison with the theoretical behaviour.
207 citations
TL;DR: In this paper, a simple ground plane structure that can reduce mutual coupling between closely-packed antenna elements is proposed, which consists of a dumb-bell-like pattern etched in a single ground plane.
Abstract: A simple ground plane structure that can reduce mutual coupling between closely-packed antenna elements is proposed. The structure consists of a dumb-bell-like pattern etched in a single ground plane. It is found that isolation of more than -40-dB can be achieved between two parallel individual planar inverted F antennas sharing a common ground plane. Influence of the designed defected ground plane structure on the radiation pattern is also investigated.
178 citations
TL;DR: In this article, a dual-band metamaterial-inspired small monopole antenna is proposed for WiFi applications, where the regular monopole resonance is exploited to create a second resonance for the lower WiFi band while maintaining the antenna's small form factor.
Abstract: A simple dual-band metamaterial-inspired small monopole antenna is proposed for WiFi applications. In addition to the regular monopole resonance, the metamaterial-inspired loading is exploited to create a second resonance for the lower WiFi band while maintaining the antenna's small form-factor. The measured S parameters and radiation patterns show that the proposed design is suitable for emerging WLAN applications.
152 citations
TL;DR: In this article, a low profile printed antenna with triple band operation is presented for simultaneous use in wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications.
Abstract: A low profile printed antenna with triple band operation is presented for simultaneous use in wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The antenna consists of a rectangular radiating element fed asymmetrically by a 50 Ω microstrip line and a shaped trapezoidal ground plane. Rectangular horizontal strips are attached to the radiation element to form different current paths which make the antenna resonate in WLAN and WiMAX frequency bands. The antenna operates in dipole configuration outlining overall dimensions of 38×30×0.8 mm3.
139 citations
TL;DR: In this paper, an oxide-confined 850 nm vertical-cavity surface-emitting laser operating at 40 Gbit/s at current densities ~10 kA/cm 2 is realized.
Abstract: Oxide-confined 850 nm vertical-cavity surface-emitting lasers operating at 40 Gbit/s at current densities ~10 kA/cm 2 are realised. The deconvoluted rise time of the device is below 10 ps and remains hardly temperature sensitive up to 100degC.
138 citations
TL;DR: A 1.28 Tbaud data signal is demonstrated, which is the highest symbol rate yet reported, and is demultiplexed in a nonlinear optical loop mirror, resulting in error-free performance with a BER < 10 -9 for all 128 demultipalxed channels.
Abstract: A 128 Tbaud data signal is demonstrated, which is the highest symbol rate yet reported The data signal is formed by optical time-division multiplexing of 128 data channels at 10 Gbit/s OOK in a single polarisation The generated 128 Tbit/s data signal is demultiplexed in a nonlinear optical loop mirror, resulting in error-free performance with a BER<10−9 for all 128 demultiplexed channels
122 citations
TL;DR: In this paper, a new high-performance CMOS current comparator is proposed, which achieves a 0.6 ns delay for a 100 nA input current at 1.8 V supply, which is about eight times faster than Traff's comparator.
Abstract: A new high-performance CMOS current comparator is proposed. By adding two inverters in the feedback loop of Traff's comparator, the proposed comparator exhibits significant speed improvement especially for low input currents. Simulated in a 0.18 mum CMOS technology, the comparator achieves a 0.6 ns delay for a 100 nA input current at 1.8 V supply, which is about eight times faster than Traff's comparator.
117 citations
TL;DR: An infrared small target detection method based on the least squares support vector machine (LS-SVM) is proposed and experimental results demonstrate that the presented method is robust and efficient.
Abstract: An infrared small target detection method based on the least squares support vector machine (LS-SVM) is proposed. The LS-SVM model is applied to generate a row and a column directional highpass template filters. By filtering the original infrared image with the two templates, respectively, and fusing the two filtered images, the possible small target can be extracted. Experimental results demonstrate that the presented method is robust and efficient.
112 citations
TL;DR: By coupling a stub-loaded open-loop resonator onto the back of a CPW-fed mirrored-L monopole, a novel triple-band planar antenna has been achieved and is presented as discussed by the authors.
Abstract: By coupling a stub-loaded open-loop resonator onto the back of a CPW-fed mirrored-L monopole, a novel triple-band planar antenna has been achieved and is presented. The proposed antenna features a compact structure with reasonable gains. The measured bandwidths for the distinct triple-band are 2.27-2.87-GHz, 3.4-4.15-GHz and 5.11-6.7-GHz. Omnidirectional radiation patterns for the three bands are observed. Simulations are confirmed by the experimental results, which ensure that the proposed antenna is well suited for WiFi and WiMAX applications.
110 citations
TL;DR: In this article, the operation GaN nanowire, light-emitting diodes that are based on a uniform and scalable Nanowire process was investigated and it was shown that the electroluminescence intensity grows superlinearly with current.
Abstract: GaN optoelectronic devices based on nanowires offer potential advantages that merit further investigation for applications in solid-state lighting and displays. Reported is the operation GaN nanowire, light-emitting diodes that are based on a uniform and scalable nanowire process. For light-emitting diodes consisting of approximately 300 nanowire pn homojunctions, operating in parallel, the electroluminescence intensity was found to grow superlinearly with current. For individual nanowire light-emitting diodes the forward and reverse leakage current was<1 pA. The low leakage current of individual light-emitting nanowire diodes indicates that surface effects do not dominate the electrical behaviour of these LEDs.
110 citations
TL;DR: In this paper, a microstrip low-pass filter with enhanced performance is developed, which is based on a novel patch resonator that features strong slow-wave effects, and can also implement either an improved roll-off or an enhanced stop-band.
Abstract: A microstrip lowpass filter with enhanced performance is developed. The studied filter is based on a novel patch resonator that features strong slow-wave effects, and can also implement either an improved roll-off or an enhanced stop-band. A demonstrator filter with 3 dB cutoff frequency fc =2.4=GHz is optimally designed, fabricated and measured. Results indicate that a roll-off of 92.5=dB/GHz together with a relative stop-band bandwidth of 135.5= (referred to a 30=dB suppression) is obtained while achieving a highest figure-of-merit of 10106. Both simulations and measurements are presented and compared.
TL;DR: In this article, a charge pump that minimizes the mismatch between the charging and discharging currents and keeps the currents constant across a wide output voltage range is described, where the improved current matching helps reduce the static phase offset and reference spur of a phase-locked loop (PLL) and the constant currents help control the PLL dynamics precisely.
Abstract: A charge pump that minimises the mismatch between the charging and discharging currents and keeps the currents constant across a wide output voltage range is described. The improved current matching helps reduce the static phase offset and reference spur of a charge-pump phase-locked loop (PLL) and the constant currents help control the PLL dynamics precisely. The proposed charge pump with dual compensation circuits demonstrates current mismatch of less than 3.2% and pump-current variation of 1.7% over the output voltage ranging from 0.2 to 1.0%V in the 0.13%%m CMOS process with 1.2%V supply.
TL;DR: In this article, the authors demonstrate that a low-threshold quantum dot laser diode can achieve very low internal optical loss with a lasing threshold current density of 10.4 A/cm 2.
Abstract: Data are presented demonstrating that a low-threshold quantum dot laser diode can achieve very low internal optical loss. The broad-area laser diode operates at the wavelength 1.22 m and delivers 2 W of power from a 1.6 cm-long cavity with uncoated facets, with a lasing threshold current density of 10.4 A/cm 2 . The laser diode's internal waveguide loss is extracted from cavity length measurements to be ~0.25cm -1 . The interdependence of threshold current density and internal optical loss is discussed.
TL;DR: In this article, a novel methodology for ultra-thin and broadband radar absorbing material (RAM) design is proposed, based on periodically arranging two different types of thin planar slabs that are both artificial magnetic conductors (AMCs) with different phase characteristics that are arranged in a checkerboard configuration.
Abstract: A novel methodology for ultra-thin and broadband radar absorbing material (RAM) design is proposed. The method is based on periodically arranging two different types of thin planar slabs that are both artificial magnetic conductors (AMCs) with different phase characteristics that are arranged in a checkerboard configuration. By controlling the phase difference between the two types of AMC slabs, the energy which is normally incident on the screen is redirected, and the RCS along the boresight is reduced over a wide frequency range.
TL;DR: ePIXfab as discussed by the authors is a service platform offering R&D oriented access to state-of-the-art 200 mm wafer-scale CMOS technology optimized for silicon photonics purposes.
Abstract: Fabless access to wafer-scale silicon photonics technology is moving silicon photonics closer to becoming a mainstream technology and opens up new exciting areas for research at the same time. It is only by using wafer-scale technology that this emerging field will be able to realise its promise: to become a disruptive technology. At the basis of the rationale for silicon photonics is a complex of photonic functions integrated on a single chip, coupled to a stable, high-yield volume fabrication technology base. ePIXfab is a service platform offering R&D oriented access to state-of-the-art 200 mm wafer-scale CMOS technology optimised for silicon photonics purposes.
TL;DR: In this paper, the Weibull-gamma (WG) distribution is used for modeling fading environments when multipath is superimposed on shadowing, and the probability density, cumulative distribution, characteristic functions and the moments are derived in closed form.
Abstract: The Weibull-gamma (WG) distribution, which is appropriate for modelling fading environments when multipath is superimposed on shadowing, is introduced and studied. For this composite distribution the probability density, cumulative distribution, characteristic functions and the moments are derived in closed form. Furthermore, the average bit error and outage probabilities of a receiver operating over WG fading channels are assessed and compared with the corresponding performances obtained using other composite distributions.
TL;DR: This approach is based on Bayesian classifiers, which uses a posteriori information to determine in which class the subject belongs, yielding 88.6 and 98.3% accuracy values for SPECT and PET images, respectively, an improvement over the accuracy values reached by other existing techniques.
Abstract: An automatic tool to assist the interpretation of single photon emission computed tomography (SPECT) and positron emission tomography (PET) images for the diagnosis of the Alzheimer's disease (AD) is demonstrated. The main problem to be handled is the so-called small size sample, which consists of having a small number of available images compared to the large number of features. This problem is faced by intensively reducing the dimension of the feature space by means of principal component analysis (PCA). Our approach is based on Bayesian classifiers, which uses a posteriori information to determine in which class the subject belongs, yielding 88.6 and 98.3% accuracy values for SPECT and PET images, respectively. These results mean an improvement over the accuracy values reached by other existing techniques.
TL;DR: A segmented loop antenna is presented for ultra-high frequency (UHF) near-field radio frequency identification (RFID) applications that makes the current along the loop remain in-phase even though the perimeter of the loop is comparable to the operating wavelength, so that a strong and uniform magnetic field is generated in the region surrounding the antenna.
Abstract: A segmented loop antenna is presented for ultra-high frequency (UHF) near-field radio frequency identification (RFID) applications. The proposed segmented configuration makes the current along the loop remain in-phase even though the perimeter of the loop is comparable to the operating wavelength, so that a strong and uniform magnetic field is generated in the region surrounding the antenna. The antenna printed on a FR4 printed circuit board (PCB) with an overall size of 160 times 180 times 0.5 mm achieves good impedance matching and uniform magnetic field distribution over an operating bandwidth of 800-1040 MHz, which is desirable for UHF near-field RFID reader applications.
TL;DR: In this article, a two-port frequency reconfigurable antenna for cognitive radios is presented, which is composed of a disc monopole with two ports that excite at opposite sides; one port is very wideband and consists of a coplanar feed line and the other port is tunable narrowband and consisting of a microstrip feed line with defect slots in its ground plane.
Abstract: A two port frequency reconfigurable antenna for cognitive radios is presented. It is composed of a disc monopole with two ports that excite at opposite sides; one port is very wideband and consists of a coplanar feed line and the other port is tunable narrowband and consists of a microstrip feed line with defect slots in its ground plane. The slots act as a filter that suppresses frequencies outside the desired band, its operating frequency band can be tuned by varying the length of the slots. The two ports are decoupled by at least 10 dB through the considered frequency range. It is believed that the proposed antenna can be a good candidate for cognitive radios in generic small base stations where the narrowband port is used for operation and the wideband one is used for sensing the spectrum. For accuracy, it is important that the sensing (measurement of the interference noise) is made with the same polarisation as the operation and the proposed antenna achieves this by having the two collinear ports. To examine the presented approach, simulated and measured results are presented and good agreement is reported.
TL;DR: In this paper, an electro-optic modulator and J-band uni-travelling-carrier photodetector (UTC-PD) were used for the transmitter and a Schottky barrier diode detector was developed and fabricated for the receiver on the same epi-layer as the UTC-PD.
Abstract: 8 Gbit/s wireless data transmission using a 250 GHz millimetre-wave carrier signal is demonstrated. Photonic devices and technologies, including an electro-optic modulator and J-band uni-travelling-carrier photodetector (UTC-PD) module, were used for the transmitter. In addition, a high-efficiency Schottky barrier diode detector monolithically integrated with a ring slot antenna was developed and fabricated for the receiver on the same epi-layer as the UTC-PD.
TL;DR: By examining Moore's Law and the roadmap of conventional electronic ICs, valuable lessons in host material selection for PICs are discussed and it is believed that cost and performance may select silicon as the primary host material.
Abstract: A brief review of recent progress in photonic integrated circuits (PICs) is presented. By examining Moore's Law and the roadmap of conventional electronic ICs, valuable lessons in host material selection for PICs are discussed. Finding a primary host material for integration is necessary and vital to the success of the PIC industry. Initial success has been achieved in both InP-based and silicon-based commercial PICs; however, we believe that cost and performance may select silicon as the primary host material, with the urgency to deploy optical interconnects on Si electronic ICs as one of the main reasons. A recently introduced hybrid silicon evanescent platform and devices and silicon/germanium APDs are reviewed as examples to understand the viability of silicon PICs and lead to an understanding of a possible roadmap to next generation large-scale PICs.
TL;DR: In this paper, rows of normalised Riemann matrices are selected as phase sequence vectors for the selected mapping (SLM) technique, which is one of the promising PAPR reduction techniques for OFDM.
Abstract: One of the main issues of orthogonal frequency division multiplexing (OFDM) is the high peak-to-average power ratio (PAPR) of the transmitted signal which adversely affects the complexity of power amplifiers. The selected mapping (SLM) technique is one of the promising PAPR reduction techniques for OFDM. In this reported work, rows of normalised Riemann matrices are selected as phase sequence vectors for the SLM technique. MATLAB simulations show PAPR reduction of around 2.3 dB using the proposed method compared with methods reported in the literature.
TL;DR: In this paper, an oxide confined 850 nm VCSEL biased at a current density of 11-14 kA/cm2 was used for error free transmission over multimode fiber at data rates up to 32 Gbit/s at 25C and 25 Gbps at 85C.
Abstract: Error free transmission over multimode fibre at data rates up to 32 Gbit/s at 25C and 25 Gbit/s at 85C using an oxide confined 850 nm VCSEL biased at a current density of 11–14 kA/cm2 is demonstrated. The VCSEL is optimised for high-speed by reducing capacitance and self-heating and by using strained InGaAs quantum wells for high differential gain.
TL;DR: In this paper, a circularly-polarized antenna which has a novel feeding structure like a substrate integrated waveguide, a cavity-backed resonator and a conventional ring-slot antenna is proposed for right-handed circular polarisation (RHCP) in a single-layered fabrication.
Abstract: A circularly-polarised antenna which has a novel feeding structure like a substrate integrated waveguide, a cavity-backed resonator and a conventional ring-slot antenna is proposed for right-handed circular polarisation (RHCP) in a single-layered fabrication. The CP generation and broadband impedance matching characteristics are accomplished by using a simple shorting via between the top patch and bottom ground plane and inserting inductive via arrays at the input port, respectively. A broadband impedance bandwidth of 18.74% and a RHCP axial ratio of 2.3% have been obtained under the condition of less than VSWR 2:1 and axial ratio -3 dB, respectively.
TL;DR: A novel approach for personal identification using finger images which exploits the orientation features from the random knuckle lines using finite Radon transform is proposed and achieves highly promising results.
Abstract: A novel approach for personal identification using finger images which exploits the orientation features from the random knuckle lines using finite Radon transform is proposed. The feasibility of this approach is rigorously evaluated on a publically available finger knuckle database from 158 subjects and achieves highly promising results.
TL;DR: In this paper, a microwave photonic filter that solves the problem of realising a single bandpass RF response is presented, based on using phase modulation together with a pair of gratings, and eliminates the baseband response and periodic spectral response of typical FIR filters.
Abstract: A new microwave photonic filter that solves the problem of realising a single bandpass RF response is presented. The filter is based on using phase modulation together with a pair of gratings, and eliminates the baseband response and periodic spectral response of typical FIR filters. Experimental results demonstrate a single passband square-type bandpass filter response, and operation to high frequencies.
TL;DR: This work has shown that the discrete Fourier transform of a Zadoff-Chu sequence is a time-scaled conjugate of the ZC sequence, multiplied by a constant factor, which can be used to generate 3GPP LTE access preambles more efficiently than the standard suggests.
Abstract: An important property of a Zadoff-Chu (ZC) sequence is derived, namely that the discrete Fourier transform (DFT) of a ZC sequence is a time-scaled conjugate of the ZC sequence, multiplied by a constant factor. This result has many practical applications. For example, it can be used to generate 3GPP LTE access preambles more efficiently than the standard suggests as it allows the DFT of a ZC sequence of prime length P to be computed with P instead of PlogP arithmetic operations.
TL;DR: In this article, a tunable phase shifter using liquid crystal (LC) was presented, which offers a performance of above 60 differential phase shift per dB insertion loss and a minimum tuning speed of 340 ms.
Abstract: A tunable phase shifter using liquid crystal (LC) is presented. The device is fabricated in a fashion similar to LC displays which makes fabrication very simple compared, for example, to MEMS approaches. At the targeted operation frequency of 20 GHz the device offers a performance of above 60 differential phase shift per dB insertion loss and a minimum tuning speed of 340 ms.
TL;DR: In this paper, a differential-mode ultra-wideband (UWB) bandpass filter on a microstrip line is proposed and implemented with good common-mode suppression, and a filter is then fabricated for experimental verification of the proposed technique.
Abstract: A differential-mode ultra-wideband (UWB) bandpass filter on a microstrip line is proposed and implemented with good common-mode suppression. A sixth-stage branch-line differential-mode bandpass filter is designed with the specified UWB passband. By introducing two pairs of open-circuited stubs in the symmetrical plane, the differential-mode frequency response remains unchanged but its common-mode counterpart is reshaped to achieve the stopband in the overall UWB. A filter is then fabricated for experimental verification of the proposed technique.
TL;DR: In this article, it has been found that there is an optimal coupling condition that corresponds to the maximum power transfer for a series-tuned IPT system, and both theoretical and experimental studies have proven this finding.
Abstract: It is a common misconception that tighter coupling leads to higher power transfer in designing an IPT (inductive power transfer) system. It has been found that there is an optimal coupling condition that corresponds to the maximum power transfer for a series-tuned IPT system. Both theoretical and experimental studies have proven this finding, and the results obtained are very important for future IPT system analysis and design.