Showing papers in "Electronics Letters in 2010"
TL;DR: A modified merged capacitor switching (MCS) scheme is proposed for the successive approximation register (SAR) analogue-to-digital converter (ADC) and achieves lowest switching energy among existing switching schemes.
Abstract: 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.
277 citations
TL;DR: In this paper, a memristor based oscillator is presented, which generates a steady periodic orbit and has a transition from transient chaotic to steady periodic behaviour, but the complicated dynamical behaviour is extremely dependent on the initial condition of the Memristor.
Abstract: By replacing Chua's diode in the canonical Chua's oscillator with a smooth flux-controlled memristor, a memristor based oscillator is presented. The memristor oscillator generates a steady periodic orbit and has a transition from transient chaotic to steady periodic behaviour. The complicated dynamical behaviour is extremely dependent on the initial condition of the memristor.
169 citations
TL;DR: A new approach to realise computer monitor flickers that can be used to elicit steady-state visual evoked potentials (SSVEP) at a flexible frequency is proposed and an SSVEP-based brain-computer interface with 16 targets was implemented.
Abstract: A new approach to realise computer monitor flickers that can be used to elicit steady-state visual evoked potentials (SSVEP) at a flexible frequency is proposed. An SSVEP-based brain-computer interface (BCI) with 16 targets was then implemented using the proposed method. In an online test on three subjects, a high information transfer rate of 75.4 bits/min was achieved.
166 citations
TL;DR: In this article, a memristor emulator has been used to demonstrate the connection between resistors with memory and meminductors, showing a useful and interesting connection between the three memory elements.
Abstract: Electronic circuits with memristors (resistors with memory) that operate as memcapacitors (capacitors with memory) and meminductors (inductors with memory) are proposed. Using a memristor emulator, the suggested circuits have been built and their operation has been demonstrated, showing a useful and interesting connection between the three memory elements.
149 citations
TL;DR: Investigated is the outage performance of cognitive wireless relay networks in a fading environment, where the secondary users including the source and relays may take advantage of a frequency band of a licensed (primary) user by opportunistically transmitting with high power as long as the interference it incurs is not deemed harmful by the licensee.
Abstract: Investigated is the outage performance of cognitive wireless relay networks in a fading environment, where the secondary users including the source and relays may take advantage of a frequency band of a licensed (primary) user by opportunistically transmitting with high power as long as the interference it incurs is not deemed harmful by the licensee. The relation between the secondary channel performance and the interference inflicted on the primary user is quantified.
148 citations
TL;DR: In this paper, a joint direction of arrival (DOA)-direction of departure (DOD) estimation in bistatic MIMO radar is proposed, based on the decomposition of the 2D direction finding into double 1D finding, using the ESPRIT method to estimate the DOD and the Root-MUSIC for the DOA estimation.
Abstract: A new method for joint direction of arrival (DOA)-direction of departure (DOD) estimation in bistatic MIMO radar is proposed. This method, based on the decomposition of the 2D direction finding into double 1D direction finding, uses the ESPRIT method to estimate the DOD and the Root-MUSIC for the DOA estimation. Some simulation results are presented to verify the efficiency of this approach.
144 citations
TL;DR: Error-free transmission at bit rates up to 40 Gbit/s in a back-to-back configuration and up to 35 Gbps over 100 m multimode fiber using a directly modulated oxide confined 850 nm vertical cavity surface emitting laser was demonstrated in this paper.
Abstract: Error-free transmission is demonstrated at bit rates up to 40 Gbit/s in a back-to-back configuration and up to 35 Gbit/s over 100 m multimode fibre using a directly modulated oxide confined 850 nm vertical cavity surface emitting laser.
129 citations
TL;DR: Digital signal transmission at 300 GHz using a versatile Schottky mixer based measurement system designed for terahertz communication channel modelling and propagation studies is demonstrated and analysed.
Abstract: Recently, analogue video signal transmission at 300 GHz has been demonstrated using a versatile Schottky mixer based measurement system designed for terahertz communication channel modelling and propagation studies. In this reported work, digital signal transmission at 300 GHz using this system is demonstrated and analysed. The performance of the digital transmission setup is characterised with respect to phase noise and modulation errors. For demonstration, high data rate digital video signals have been transmitted over a distance of up to 52 m.
122 citations
TL;DR: Experiments showed that this novel image enhancement approach can not only enhance an image's details but can also preserve its edge features effectively.
Abstract: Low contrast and poor quality are main problems in the production of medical images. By using the wavelet transform and Haar transform, a novel image enhancement approach is proposed. First, a medical image was decomposed with wavelet transform. Secondly, all high-frequency sub-images were decomposed with Haar transform. Thirdly, noise in the frequency field was reduced by the soft-threshold method. Fourthly, high-frequency coefficients were enhanced by different weight values in different sub-images. Then, the enhanced image was obtained through the inverse wavelet transform and inverse Haar transform. Lastly, the image's histogram was stretched by nonlinear histogram equalisation. Experiments showed that this method can not only enhance an image's details but can also preserve its edge features effectively.
117 citations
TL;DR: An optical fiber sensor system for humidity and temperature, comprising two Bragg gratings recorded in silica and polymer fibre, has been characterised in this paper, and the response of this system is very well conditioned (2-norm condition number = 8.8).
Abstract: An optical fibre sensor system for humidity and temperature, comprising two Bragg gratings recorded in silica and polymer fibre, has been characterised. The response of this system is very well conditioned (2-norm condition number = 8.8) and consequently uncertainties in wavelength measurement do not lead to large errors in the recovered humidity and temperature.
106 citations
TL;DR: In this article, it was proved that all Boolean functions can be computed using two memristors, and a recursive conjunctive form for Boolean functions was introduced and its universality was shown.
Abstract: It is proved that all Boolean functions can be computed using two memristors. To achieve this, a recursive conjunctive form for Boolean functions is introduced and its universality shown.
TL;DR: In this article, a recently published circuit that operates as a memcapacitor (MC), utilising a memristor (MR) emulator, is analyzed with a confirmation that it simulates MC only approximately.
Abstract: A recently published circuit that operates as a memcapacitor (MC), utilising a memristor (MR) emulator, is analysed with a confirmation that it simulates MC only approximately. A MR to MC mutator is designed by means of off-the-shelf circuits. The SPICE analysis confirms that this circuit transforms exactly the constitutive relation of MR into the constitutive relation of MC.
TL;DR: In this paper, an improved recycling structure for an operational transconductance amplifier is proposed, which separates the AC path from the DC path, and achieves a significant boost in transconductances under the same power and area budget.
Abstract: An improved recycling structure for an operational transconductance amplifier is proposed. The proposed structure separates the AC path from the DC path, and achieves a significant boost in transconductance under the same power and area budget. A folded-cascode amplifier employing the improved recycling structure was implemented in SMIC standard 0.13 μm CMOS process. Simulation results show that the enhancement of transconductance leads to 230% improvement in gain-bandwidth product and 13 dB boost in gain compared with the conventional folded cascode.
TL;DR: A distributed channel rendezvous scheme that can be implemented without slot synchronisation which is hard to accomplish in a distributed manner is presented.
Abstract: In multichannel access networks, nodes must establish a link on a channel before data transmission begins. To find such a channel, either a centralised or a distributed approach may be employed. Presented is a distributed channel rendezvous scheme. The scheme determines the order, in which two nodes visit available channels to rendezvous within 2N+1 slots, where N is the number of channels and a slot is the minimum interval required to establish a link between any pair of nodes that are in a common channel. More notably, the scheme can be implemented without slot synchronisation which is hard to accomplish in a distributed manner.
TL;DR: In this article, a new approach to achieving simultaneous beam steering and low sidelobe levels in time-modulated linear arrays is presented, which relies solely on time-switching of the array elements and does not require the use of additional amplitude weighting.
Abstract: A new approach to achieving simultaneous beam steering and low sidelobe levels in time-modulated linear arrays is presented. The technique relies solely on time-switching of the array elements and does not require the use of additional amplitude weighting. Numerical examples are presented for a 16-element linear array.
TL;DR: In this article, a methodology for SPICE modeling of a memcapacitor is described, where the model is compounded of the submodel of the state-space system, representing the memory effect of the device, which depends on the concrete physical implementation of a device, and of a capacitor, the capacitance of which is controlled by the system state.
Abstract: A methodology for SPICE modelling of a memcapacitor is described. The model is compounded of the submodel of the state-space system, representing the memory effect of the device, which depends on the concrete physical implementation of the device, and of a capacitor, the capacitance of which is controlled by the system state. The basic fingerprints of the memcapacitor are demonstrated in the example of a charge-controlled memcapacitor.
TL;DR: In this paper, a sign subband adaptive filter (SSAF) for acoustic echo cancellation is proposed, which is derived by minimising the L 1-norm of the subband a posteriori error vector subject to a constraint on the tap-weight vector of the filter.
Abstract: A sign subband adaptive filter (SSAF) for acoustic echo cancellation is proposed, which is derived by minimising the L1-norm of the subband a posteriori error vector subject to a constraint on the tap-weight vector of the filter. In addition, a variable regularisation parameter (VRP) is introduced to improve the performance of the SSAF. Simulation results are presented to verify the good robustness of the proposed VRP-SSAF against double-talk.
TL;DR: In this paper, a cavity-backed active slot antenna oscillator is proposed, the operation frequency of which can be tuned by means of a properly connected varactor, which may overcome potential problems such as heat dissipation and unwanted surface wave modes in large array implementations.
Abstract: A substrate integrated waveguide (SIW) cavity backed active slot antenna oscillator is proposed, the operation frequency of which can be tuned by means of a properly connected varactor. The cavity backed structure permits overcoming potential problems such as heat dissipation and unwanted surface wave modes in large array implementations, and may provide better phase noise performance. The use of SIW technology permits a cost-effective fabrication process and simple implementation at millimetre-wave frequency, for radar and communication applications. Full-wave FEM-based analysis is used for the design of the radiating structure, while harmonic balance and transient simulations are employed in the design of the active antenna oscillator and in the study of the stability of its steady-state solutions. Tunable active antenna prototypes have been implemented and measured.
TL;DR: A simplified algorithm for the check node processing of extended min-sum non-binary LDPC decoders is proposed, which can reduce the number of compare operations by a factor of three at the elementary check node level.
Abstract: 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.
TL;DR: A photonic crystal fiber interferometer that operates in reflection mode for humidity detection is presented for the first time, which has the advantage that it does not require the use of any hygroscopic material.
Abstract: A photonic crystal fibre interferometer that operates in reflection mode for humidity detection is presented for the first time, which has the advantage that it does not require the use of any hygroscopic material. The fabrication of the sensor head is therefore simple since it only involves cleaving and splicing. The all-silica nature of the device has potential for many applications.
TL;DR: In this paper, a segmented loop antenna with capacitive couplers is proposed for ultra-high frequency (UHF) near-field radio frequency identification (RFID) applications, which is capable of generating a strong and uniform magnetic field in a near field zone even though the perimeter of the loop is comparable to the operating wavelength.
Abstract: A segmented loop antenna with capacitive couplers is proposed for ultra-high frequency (UHF) near-field radio frequency identification (RFID) applications, which is capable of generating a strong and uniform magnetic field in a near-field zone even though the perimeter of the loop is comparable to the operating wavelength. As an example, an antenna printed onto an FR4 printed circuit board with an interrogation zone of 154 × 154 mm exhibits good impedance matching and uniform magnetic field distribution over an operating bandwidth of 790-1000 MHz, which is desirable for UHF near-field RFID reader applications.
TL;DR: In this paper, a filter-based technique was used to extract the four parameters that characterise a single-dispersion Cole-Cole impedance model without direct measurement of the impedance real and imaginary parts.
Abstract: A filter-based technique to extract the four parameters that characterise a single-dispersion Cole-Cole impedance model without direct measurement of the impedance real and imaginary parts is reported. Experimental results in the range 100 Hz-5 MHz using apples, apricots and kiwi fruits are given and results are compared with numerical simulations of the acquired model.
TL;DR: In this article, a microstrip lowpass filter with quasi-elliptic response is proposed, where a coupled capacitor between adjacent radial-shape patches is introduced in interdigital form.
Abstract: A compact microstrip lowpass filter with quasi-elliptic response is proposed. To achieve compact design, both symmetrically loaded radial-shape patches and meandered main transmission line are adopted. To realise the quasi-elliptic response and strengthen the roll-off sharpness for the filter, a coupled capacitor between adjacent radial-shape patches is introduced in interdigital form. Furthermore, the adoption of radial-shape patches and the interdigital structure can introduce both serial and parallel resonance in the circuit. Thus, a wide stopband with 7th harmonic suppression is achieved. A demonstration filter with 3 dB cutoff frequency at 1.18 GHz has been designed, fabricated and measured. Results show that a relative stopband bandwidth of 132.3 (referred to a suppression degree of 15 dB) is obtained while achieving a high figure-of-merit of 11543.
TL;DR: Numerical results show the average capacity of the heterodyne DPSK FSO communication systems over gamma-gamma turbulence channels can be evaluated with the effect of atmospheric turbulence conditions, beamwidth and jitter variance.
Abstract: A closed-form expression for the average capacity of the heterodyne differential phase shift keying (DPSK) free-space optical (FSO) communication systems over gamma-gamma turbulence channels is derived by considering the effect of pointing errors. Numerical results show the average capacity can be evaluated with the effect of atmospheric turbulence conditions, beamwidth and jitter variance. Meanwhile, these results verify the accuracy of our mathematical analysis. This work can be helpful for the heterodyne DPSK FSO communication system designer.
TL;DR: A review of the state of the art of electronic sources based on semiconductor devices that have either demonstrated substantial amounts of output power or have a strong potential of producing significant output powers at frequencies above 300 GHz is presented in this article.
Abstract: A review is presented of the state of the art of electronic sources based on semiconductor devices that have either demonstrated substantial amounts of output power or have a strong potential of producing significant output powers at frequencies above 300 GHz. Both fundamental sources and harmonic power generation using varactor or varistor diodes are discussed. The key devices are Schottky diodes, heterojunction barrier varactors, heterojunction bipolar transistors, high-electron mobility transistors, resonant tunnelling diodes, tunnel-injection transit-time devices, Gunn devices, and superlattice electron devices.
TL;DR: In this article, a dual-band dual-mode patch antenna based on the resonant-type metamaterial transmission line is proposed, which can provide zerothmode resonance at the lower frequency and positive-mode resonance in the upper frequency.
Abstract: A dual-band dual-mode patch antenna based on the resonant-type metamaterial transmission line is proposed. The resonant-type metamaterial transmission line can provide zeroth-mode resonance at the lower frequency and positive-mode resonance at the upper frequency. For improvement of radiation efficiency, a complementary single split ring resonator is introduced to realise the resonant-type metamaterial transmission line. The equivalent circuit model is applied to analyse and design the proposed antenna. This antenna exhibits monopole-like radiation pattern in the lower band and patch-like radiation pattern in the upper band. Simulation and experimental results are used to verify the theoretical prediction.
TL;DR: In this paper, phase noise characterisation of two 10 GHz cryogenic sapphire oscillators exhibiting frequency stability higher than 3×10 -15 is reported, one of these oscillators developed for the deep space navigation ground stations of the European Space Agency, incorporates a closed cycle cryocooler as cold source.
Abstract: The phase noise characterisation of two 10 GHz cryogenic sapphire oscillators exhibiting frequency stability higher than 3×10 -15 is reported. One of these oscillators developed for the deep space navigation ground stations of the European Space Agency, incorporates a closed cycle cryocooler as cold source. Near the carrier, the measured phase noise is limited by a flicker frequency noise: S ? (f)=-30log(f)-98 dBrad 2 /Hz.
TL;DR: In this paper, the triple-band notched ultra-wideband (UWB) antenna is designed to minimize the level of cross-coupling among the three notched elements.
Abstract: Proposed is the design strategy for the triple-band notched ultra-wideband (UWB) antenna emphasising the rejection characteristic at 3.5/5.5/8.2 GHz bands. The essence of the design strategy is embedding the three notching elements onto the primitive antenna to serve as respective stop band filters. On embedding, the hot issue is how to minimise the level of cross-coupling among the three elements because no coupling leads to set its distinct stop bands orthogonally. Owing to the complete unmatched appearances in shapes and the optimised arrangement of elements, they are least of all in the coupling and thus the proposed antenna can be engineered to operate at specific frequencies. Measured results show the validity of the suggested design strategy.
TL;DR: AlGaN/GaN HEMTs have been fabricated directly on (111) oriented single crystal diamond with 1.3 x 10(13) cm(-2) channel sheet charge density and 731 cm(2)/Vs mobility.
Abstract: AlGaN/GaN HEMTs have been fabricated directly on (111) oriented single crystal diamond with 1.3 x 10(13) cm(-2) channel sheet charge density and 731 cm(2)/Vs mobility. 0.2 mu m gate length devices showed 0.73 A/mm maximum drain current density and f(T) and f(max) cutoff frequencies of 21 and 42 GHz.