Showing papers in "Electronics Letters in 2016"

Extreme multistability in a memristive circuit

Abstract: A memristive Chua's circuit regarded as a paradigm is reconsidered to exhibit its extreme multistability in this Letter. Memristor initial state-dependent dynamics is analysed and the coexistence of infinitely many attractors related to memristor initial states is revealed by numerical simulations and circuit simulations. The dynamical behaviour just reflects the emergence of extreme multistability in the memristive circuit.

Video anomaly detection and localisation based on the sparsity and reconstruction error of auto-encoder

Abstract: A fast and accurate video anomaly detection and localisation method is presented. The speed and localisation accuracy are two ongoing challenges in real-world anomaly detection. We introduce two novel cubic-patch-based anomaly detector where one works based on power of an auto-encoder (AE) on reconstituting an input video patch and another one is based on the power of sparse representation of an input video patch. It is found that if an AE is efficiently trained on all normal patches, the anomaly patch in testing phase has a more reconstruction error than a normal patch. Also if a sparse AE is learned based on normal training patches, we expect that the given patch to AE is represented sparsely. If the representation is not enough sparse it is considered as a good candidate to be anomaly. For being more fast, these two detectors are combined as a cascade classifier. First, all small patches on test video frame are scanned, those which have not enough sparse representation are resized and sent to next detector for more careful evaluation. The experiment results show that the method mentioned here has a better performance especially in run-time measure than state-of-the-art methods on two UMN and UCSD benchmarks.

Absorptive frequency selective surface using parallel LC resonance

Abstract: A frequency selective surface with absorptive/ transmissive property is represented. It allows waves at high frequency around 10 GHz to transmit with very low insertion loss by using the resonance between a parallel microstrip LC structure. It also possesses a wide absorption over lower band by inserting lumped resistors into elements. The absorption band is over 3–9 GHz. A prototype is fabricated and its absorptive/ transmissive performance is measured.

S-shaped periodic defected ground structures to reduce microstrip antenna array mutual coupling

Abstract: A novel S-shaped periodic defected ground structure (PDGS) is proposed to reduce mutual coupling between antenna elements. Coplanar placed antenna elements work at the same frequency band with centre frequency 2.57 GHz. Centre-to-centre distance between the antenna elements is 50 mm which is ~0.43λ. The PDGS is three S-shaped defected ground structure units placed between microstrip antenna elements. By using the proposed PDGS, more than 40 dB mutual coupling reduction between microstrip antenna elements is achieved.

Design of adder and subtractor circuits in majority logic-based field-coupled QCA nanocomputing

Abstract: Quantum-dot cellular automata (QCA) is an emerging field-coupled nanotechnology that promises to outperform existing CMOS technology. Single-layer QCA designs of full adder, full subtractor, ripple carry adder, and ripple borrow subtractor is proposed. The proposed designs are improved over both existing single-layer designs and multilayer designs.

Compact UWB monopole antenna for internet of things applications

Abstract: A structure of a compact ultra-wideband monopole antenna has been presented. The antenna consists of a microstrip-fed rectangle radiator as well as a ground plane with a rectangle slit and an L-shaped stub. The critical factor in achieving a small size is a careful design procedure involving numerical optimisation of all geometry parameters of the antenna aiming at explicit size reduction while maintaining acceptable electrical performance. The final design exhibits dimensions of only 9.45 × 18.5 mm and a footprint of 175 mm 2 . Experimental validation and comparisons with competitive designs are also provided.

Printed eight-element MIMO system for compact and thin 5G mobile handest

Abstract: A new printed MIMO system with eight elements for a 5G mobile terminal is investigated. The MIMO system consists of printed planar inverted-F antenna elements operating at GSM1900 (1880-1920 MHz), LTE2300 (2300-2400 MHz) and LTE2500 (2540-2620 MHz). The antenna elements have a compact size of 14 mm × 15 mm and are deployed on the non-metalised part of a PCB with dimensions 136 mm × 68.8 mm × 1 mm. By only utilising radiation pattern diversity, good isolations and envelope correlation coefficients for both MIMO systems are achieved. The mean effective gains of the antenna elements are also presented.

Improved nested array with hole-free DCA and more degrees of freedom

Abstract: A new linear sparse array based on the nested array is proposed, which enjoys all the good properties of the two-level nested array, and can provide more degrees of freedom (DOF). The new array is constructed by two uniform linear arrays (ULAs) and an additional sensor. The sensor locations, the array aperture, and the achievable DOF from its difference co-array (DCA) are all benefited for closed-form expressions. Furthermore, the resulting DCA is kept as a hole-free ULA. The optimal numbers of sensors in the two ULAs provided the total number of physical sensors are derived. This new array can resolve more sources and achieve better angle estimation performance than the two-level nested array. Simulation results validate these conclusions.

Compact MIMO/diversity slot antenna for UWB applications with band-notched characteristic

Abstract: A novel MIMO sharp band-notched antenna with high isolation for UWB applications is presented. The antenna consists of two antenna elements with an overall area of 18 × 36 mm2. A T-shaped stub is extruded in the ground plane to improve isolation and an L-shaped stub to introduce band-notched function C-band (3.62–4.77 GHz). The designed antenna possesses a low mutual coupling of <−20 dB over the operating band from 2.9 to 20 GHz. The performance of this antenna is studied in terms of isolation between the two ports, radiation pattern, efficiency, realised gain, and envelope correlation coefficient.

Wide-angle quad-band polarisation-insensitive metamaterial absorber

Abstract: Closed ring resonator (CRR)-based quad-band metamaterial absorber is presented. The unit cell of proposed absorber consists of four separate CRRs which are diagonally connected to square patches enclosed within an individual CRR. The structure is fabricated on 0.8 mm-thick FR4 substrate. Simulated peak absorptivities of 98.5, 97.7, 94.8, and 96% are obtained at 4.34, 6.68, 8.58, and 10.64 GHz, respectively. The measured and simulated absorption characteristics of the proposed absorber are in good agreement. The proposed absorber is wide angle and polarisation insensitive and has identical absorption characteristics for both transverse-electric and transverse-magnetic polarised radiations.

Super-resolution orbital angular momentum based radar targets detection

Abstract: Radiating twisted beams, orbital angular momentum (OAM) based radar provides a new perspective for present radar techniques. However, estimation methods now used has a demerit of resolution. Thus, we raised multiple signal classification (MUSIC) algorithm to improve resolution ability based on this innovative concept. The echo model based on uniform circular array for MUSIC was first built. In contrast to uncorrelated signals in classical MUSIC algorithm, echo signals from targets are fully coherent with each other. Spatial smoothing technique was subsequently utilised in OAM regime to tackle it. Simulation results showed the super-resolution capacity of MUSIC to detect objectives compared with the traditional fast Fourier transform method.

Dielectric and work function engineered TFET for ambipolar suppression and RF performance enhancement

Abstract: A novel approach to suppress the ambipolar behaviour and enhance RF parameters is proposed for the first time. For this, the dielectric and gate material work function engineering is used to suppress the ambipolar behaviour individually. Further, the combination of gate dielectric and gate material work function engineering is used to suppress the ambipolar conduction in huge amount and to eliminate the hot carriers effects. Apart from these, the proposed work improves the ON-state current and RF figures of merit for symmetric devices.

High-speed error-free wireless data transmission using a terahertz resonant tunnelling diode transmitter and receiver

Abstract: An error-free wireless transmission of a 9 Gbit/s on–off keying modulated signal as well as a 4 k video signal is demonstrated using resonant tunnelling diodes as active elements in both the transmitter and the receiver. The employed system and the modulation scheme enabling the high data rate are discussed.

Wideband radar cross-section reduction by AMC

Abstract: A new planar wideband chessboard structure is designed to reduce the radar cross-section (RCS) of an object. This proposed chessboard configuration is composed of two different artificial magnetic conductor (AMC) tiles. One of these tiles is formed by saltire arrow unit cells, whereas the other one is formed by four E-shaped ones. A 180° ± 30° phase difference between these tiles achieved by precise design of the AMC unit cells of more than 9.4–23.28 GHz (85%) reduces the RCS by more than 10 dB. The fabricated board results show very good agreement with the simulated ones, which verify the ability and capability of the proposed structure.

Broadband circularly-polarised chifre-shaped monopole antenna with asymmetric feed

Abstract: A broadband circularly-polarised monopole antenna is proposed. The broadband property of the antenna is basically achieved not only by the chifre-shaped monopole radiator, but also its asymmetric feed. The circular-polarisation characteristics are greatly enhanced by adjusting the location of the monopole microstrip-feed. The antenna delivers good performance on impedance matching and circular polarisation. The measured results demonstrate that the impedance bandwidth is 72% and the 3-dB axial-ratio bandwidth reaches 41.6% with a central frequency of 2.5 GHz.

54 Gbit/s OOK transmission using single-mode VCSEL up to 2.2 km MMF

Abstract: Successful 54 Gbit/s on–off keying (OOK) transmission over 2.2 km of multimode OM4 fibre is demonstrated. The decisive advantages of the single mode over multimode vertical cavity surface emitting laser (VCSEL) in transmission experiments are shown.

High voltage and high current density vertical GaN power diodes

Abstract: We report on the realization of a GaN high voltage vertical p-n diode operating at > 3.9 kV breakdown with a specific on-resistance 1.4 kA/cm2. An effective critical electric field of 3.9 MV/cm was estimated for the devices from analysis of the forward and reverse current-voltage characteristics. Furthermore this suggests that the fundamental limit to the GaN critical electric field is significantly greater than previously believed.

Experimental verification of on-chip CMOS fractional-order capacitor emulators

Abstract: The experimental results from a fabricated integrated circuit of fractional-order capacitor emulators are reported. The chip contains emulators of capacitors of orders 0.3, 0.4, 0.5, 0.6 and 0.7 with nano-Farad pseudo-capacitances that can be adjusted through a bias current. Two off-chip capacitors are used to set the bandwidth of each emulator independently. The chip was designed in Austria microsystems (AMS) 0.35μ CMOS.

Highly linear VCO for use in VCO-ADCs

Abstract: A very simple ring-oscillator voltage-controlled oscillator (VCO) structure for use in VCO-ADC applications is presented. It has a greatly improved linearity compared with previously published VCOs. Measurement results of a 1 V, 65 nm CMOS prototype confirm the effectiveness of the proposed approach.

Wireless data transmission of 34 Gbit/s at a 500-GHz range using resonant-tunnelling-diode terahertz oscillator

Abstract: A resonant-tunnelling-diode terahertz oscillator capable of wide-band direct modulation was fabricated, and wireless data transmission at a 500-GHz range was demonstrated. An error-free transmission up to the data rate of 22 Gbit/s and a transmission with a bit error rate less than the forward error correction limit up to 34 Gbit/s were achieved.

Wideband radar cross-section reduction of patch array antenna with miniaturised hexagonal loop frequency selective surface

Abstract: Wideband radar cross-section (RCS) reduction of a microstrip patch array antenna is proposed and investigated. The design is based on replacing the solid metal ground of the antenna with a frequency selective surface (FSS) consisted of miniaturised hexagonal loop elements. The stop band of the FSS is coincident with the antenna working frequency band which is from 3.3 to 3.4 GHz. The FSS acts as the ground plane in the stop band and is transparent to the incident waves in the other frequencies. Therefore, preserving the antenna propagation characteristics, wideband RCS reduction is achieved from 4 to 16.5 GHz for vertical and horizontal polarisations. It is shown that using this FSS has a negligible effect on the impedance bandwidth, pattern and gain of the antenna. Also, there is a good agreement between the simulation and measurement results.

Broadband RCS reduction using a novel double layer chessboard AMC surface

Abstract: A novel broadband chessboard surfaces with double layer structure to reduce the radar cross-section (RCS) of an object is presented. By combining two artificial magnetic conductor (AMC) cells and a novel structure, 73% frequency bandwidth of −10 dB RCS reduction compared with a metallic plate has been obtained. In order to increase the bandwidth in chessboard structures, boards with high thickness are required, cheaper boards’ thickness are limited. An RO4003 board on an air substrate has been used. This technique, in addition to accommodating the designer with a new parameter, decreases the costs and increases the bandwidth greatly and also simulation results and measurements are in good correspondence.

Performance analysis of physical layer security over α–μ fading channel

Abstract: Recently, many works have focused on analyzing the metrics of physical layer security over different wireless channels, such as additive white Gaussian noise (AWGN), Rayleigh, Rician and Nakagami-m fading distributions. In order to extend the analysis to the general case, α-μ fading channel is considered, which can span the aforementioned cases. For this purpose, the physical layer security over α-μ fading channel is presented in this letter. The closed-form expressions for the probability of positive secrecy capacity and upper bound of the secrecy outage probability are derived. Their accuracies are assessed through comparison of theoretical analysis and simulations results.

Broadband circularly polarised implantable antenna for biomedical applications

Abstract: A compact, broadband and single-fed circularly polarised implantable patch antenna is numerically evaluated and experimentally demonstrated for industrial, scientific, and medical band (2.45 GHz) biomedical telemetry application. By inserting a cross-shaped slot with unequal-length arms in the ground plane, the proposed antenna can obtain improvement for both impedance bandwidth and axial ratio (AR) bandwidth, without increasing the backward radiation. The simulated −10 dB impedance and 3 dB AR bandwidths are 16.15% and 6.09%. The measured impedance bandwidth is 14.03%. The overall antenna size (including the superstrate) is 10 × 10 × 1.27 mm3.

Current sensor fault detection and isolation method for PMSM drives, using average normalised currents

Abstract: A new approach for current sensor fault detection and isolation (FDI) for permanent magnet synchronous motor (PMSM) drives is presented. Contrary to the classical approaches for sensors fault diagnosis, based on residual generation through observers or parity equations, the proposed technique uses the average normalised machine-phase currents. The main advantages of this approach are that it does not need any information about the PMSM or inverter models, and it involves low tuning efforts, that make it suitable for real-time implementation with good reliability. The good performance and the robustness of the proposed FDI approach are illustrated through experimental results.

High-density chipless RFID tag for temperature sensing

Abstract: A 30 bit high-density circular chipless RF identification tag based on C-shaped open end polarisation independent slots is presented. The encoding capacity of this design is enhanced in a compact size. Patch diameter of the tag is 24 mm. Circularly polarised incident plane waves are used for excitation. Data capacity of 30 bits is achieved in the frequency band of 3.1–11.7 GHz. Spectral signature-based radar cross-section results are also measured for flexible and temperature sensor integrated design. The prototype is inkjet printed on Kapton® HN heat resistant conformal sheet.

Bias-compensated affine-projection-like algorithms with noisy input

Abstract: A new class of bias-compensated affine-projection-like (APL) algorithms is proposed, in which a bias-compensation vector is derived to eliminate the bias caused by the noisy input. In addition, a new estimation method for the input noise variance is proposed which does not require the input–output noise variance ratio in advance. Simulations in a system identification context show that the proposed algorithms achieve significant improvements in steady-state misalignment as compared with the conventional APL algorithms.

Design of non-restoring binary array divider in majority logic-based QCA

Abstract: A novel quantum-dot cellular automata (QCA) design for the non-restoring binary array divider is presented, which is constructed using the proposed coplanar QCA Exclusive-OR gate and full adder The results show that proposed designs have better performances than the best existing structures in terms of common design metrics The presented 3 × 3 and 4 × 4 dividers are able to achieve 65, 75, 45% and 41, 27, 41% reductions in cell count, latency, and area, respectively

Femtosecond laser inscribed Bragg grating arrays in long lengths of polymer optical fibres; a route to practical sensing with POF

Abstract: The first practical demonstration of readily useable fibre Bragg gratings in long lengths (>20 m) of polymer optical fibres (POFs) is reported; this is an increase in fibre length that exceeds two orders of magnitude for use in the C-band. A low loss perfluorinated fibre and a femtosecond-laser, direct-write method to inscribe gratings at two different wavelengths are used. Gratings are fabricated to operate at ∼800 nm, where the optical loss is minimal, and in the C-band, commonly used with traditional optical fibres for the majority of telecommunication applications. The development of POF Bragg gratings inscribed in long fibre lengths is the first important step for the integration of practical sensing devices and could promote the use of multiplexed POF sensors. The sensors were tested and characterised and demonstrate their compatibility with a commercial Bragg grating demodulator.

First-order low-pass negative group delay passive topology

Abstract: An innovative theory on the passive circuits capable to generate low-pass negative group delay (NGD) behaviour is introduced. An identification method enabling to identify the first-order NGD simple cells built with resistor-inductor (RL)- and resistor-capacitor (RC)-networks is elaborated. The fundamental characteristics as the NGD level and cut-off frequency are formulated from the low-pass NGD circuit canonical transfer function. The NGD existence conditions are derived in function of the established topology parameters. Despite the attenuation systematically related to the passive cell nature, low-pass NGD behaviours with tens ns NGD level and tens MHz bandwidth were obtained with an example of lumped RL-network-based L-topology circuit. Transient analysis was performed to illustrate that the NGD phenomenon enables to exhibit baseband signal advance effect. The proposed NGD topology simplicity promises their potential applications especially in term of signal correction and the modern electronic system improvement.