A low-power antenna switch driver circuit with RF leakage suppression and fast switching time is implemented in a 0.25 μm silicon-on-insulator (SOI) CMOS process. It is composed of a three-stage current starved ring oscillator with a clock buffer, a charge pump and a latch-based three-state logic driver. The negative voltage from the charge pump is fed into the latch-based three-state logic driver, and it generates three states of logic level (+VDD, GND and −VDD) according to the decoder signal without any reliability issue. In addition, the proposed three-state logic driver with an optimal negative resistance value reduces the amount of the RF leakage coupling into the charge pump while maintaining its switching time fast. In the measurement, the designed switch driver circuit shows <0.1 V of voltage loss under 150 μA of current consumption. A single-pole double-throw antenna switch employing the proposed switch driver circuit is implemented in a 0.25 μm SOI CMOS process. The measurement shows higher than +38 dBm of 1 dB compression point (P1dB) and 140 ns of switching time while allowing <0.5 dB of insertion loss and >30 dB of isolation over 100 MHz to 3 GHz frequency range.

Anechoic chambers are used for indoor antenna measurements. The common method for anechoic chamber construction is to cover all inside walls by the EM absorbers. A fully metallic parabolic chamber is presented in which the propagation of the EM waves inside the chamber is controlled and they are guided to an absorber. In the proposed method, an appropriate quiet zone with plane wave illumination is obtained, and unlike ordinary anechoic chambers the absorber usage is decreased greatly. The performance of the chamber is evaluated by simulation and the results showed that the proposed method could provide a useful technique for the compact range antenna measurements.

A zinc oxide (ZnO)–reduced graphene oxide (rGO) composite thin film memristive device is reported. Further, it has been shown that it is possible to implement Hebbian learning rules like, the spike-timing-dependent plasticity, using this device. Furthermore, a circuit on PCB is developed; this circuit can imitate the biological spike firing scheme and activate the memristor synapse. The fabricated device along with the custom made circuit can be extended for developing future neuromorphic circuit applications.

Among acoustic waves sensors, the thickness shear mode resonator presents high sensitivity for the measurement of liquid viscoelastic properties, enabling the monitoring of the shear moduli, G′ G″, by using a suitable physical model. The development of an instrumental system for detecting the tau protein involved in Alzheimer's disease is proposed which will aid in understanding the mechanisms of this disease. The tau protein is present in complex products such as blood and cerebrospinal fluid. The experimental results show that the acoustic wave system allows to differentiate between tau protein solutions with different states of polymerisation.

An 8-bit 4 GS/s 8-channel time-interleaved successive approximation register (SAR) analogue-to-digital converter (ADC) is presented. To enhance the ENOB (effective number of bits), a meta-stability immunity technique is proposed, which utilises pre-installation to eliminate uncertain decision. The technique has negligible design overhead in terms of power and silicon area. The ADC chip was fabricated in a 65 nm CMOS technology. It achieves an ENOB of 7.45 bits, with 48 mW power consumption and an area of 0.075 mm².

Two low power-delay-product (PDP) dynamic CMOS circuit design techniques are proposed. The techniques can simply modify existing dynamic CMOS designs to improve dynamic circuit delay and PDP. Conventional benchmark circuits and the modified circuits using the proposed techniques are implemented in 90 nm CMOS technology with a 1.2 V power supply. Simulation results indicate that the proposed techniques can improve circuit PDP by 19.2 and 61.9% in two non-inverted dynamic benchmarks, respectively, and 6.2 and 33.72% in two inverted dynamic benchmarks, respectively.

Time-of-flight (TOF) digital converter implemented in field programmable gate array has been introduced. The operation is based on train of pulses transmission and counting received pulses in bank of counters. The bank of counters clock signal and the transmitted pulses clock signal are slightly different in frequency. This small difference is a key factor for the measurement method and is achieved by phase locked loop. TOF for the transmitted pulses is directly calculated upon counters counts. Time interval resolution for the prototype instrument is 10.4 ps and average RMS uncertainty value is 12.3 ps. There is no need for special calibration. TOF digital converter requires minimum amount of resources and is suitable for low-cost applications.

Digital-to-time converters are one of the main building blocks in time-domain signal processing. The jitter-power product is analysed and shown to scale up linearly as the full-scale delay range in current-mode logic implementations, and quadratically in CMOS logic. It is also shown that CMOS converters outperforms current-mode ones only when their output range is lower than about 1.4 times the clock period.

A smart dual-mode IO driver and termination scheme is proposed and power is efficiently consumed for both low-speed data transmission under 500 Mbit/s and high-speed data transmission up to 3.4 Gbit/s. During high speed data transmission, the driver uses near-ground signalling and pre-emphasis weight can be controlled for inter symbol interference (ISI) mitigation. The measured eye shows 17.8% vertically and 19.5% horizontally with finite impulse response (FIR) tap control for 15.75″ FR4 channel. The proto-type 2 channel single-ended driver has been implemented in 45 nm CMOS process and occupies 0.022 mm² chip area.

A dual-parameter design of expanded proximate time-optimal controller is proposed for fast point-to-point motion in typical electromechanical servo systems with a damping element. The controller initially resorts to a saturated control signal for the fastest acceleration or braking if possible and then seamlessly gives way to a linear control strategy once the motion slows down. The damping ratio and natural frequency of the linear control law are chosen as the design parameters to allow for a better tuning of the control performance. An extended-state observer is also included for simultaneous estimation of system speed and disturbance. Experimental verification is conducted on a DC motor position servo system using a TMS320F28335 board, and the effectiveness of the proposed design is demonstrated.

A set of explicit expressions for an accurate identification of unstable first order plus time delay (FOPTD) process using single relay feedback test are deduced. Thereafter, tuning rules for a feedforward and feedback combination of proportional-integral and proportional controllers are proposed to enhance the closed loop transient performance. When the process output is distorted by measurement noise, a Fourier series based curve fitting technique is utilised for the reconstruction of true process output. Benchmark examples from literature are illustrated and thereafter comparisons are made to validate the effectiveness of the proposed identification and control scheme.

Grasping postures on a human hand are generated by an effective combination of spatial motions and contact forces on individual finger linkages. The rich kinematic redundancy within its anatomy, poses critical control challenges, while emulating natural prehensile actions. A simplified grasp-formulation resolution is presented, by proposing a virtual-object imagery to define generic grasp enaction sequences. The same are conceived and controlled by a set of contact points on the imagined grasp-sphere, whose spatial conformation is guided by a serial-haptic interface. The kinaesthetic cognitions along with visual feed to an operator ushers a reliable framework for grasp execution and transfer to a robot hardware without resorting to supplementary mapping mechanisms. Stable grasps on the anthropomorphic robot set-up portrays a systematic procedure to transcribe human-like postural attributes, aided with somesthetic and visual sensations that are anticipated to steer remote operator controls.

Unlike the doublet or triplet constraints, a novel kernelised reference-wise metric learning is proposed by constructing reference-wise constraints, which contain similarity information of each sample to all reference samples. After selecting several representative training samples as the reference set, the training data are first mapped into a projected space by the reference sample matrix. Then the problem of metric learning is casted as a multi-label classification problem under the reference-wise constraints, in which an l ₂-norm regularised least squares canonical correlation analysis can be used. Besides, the formulation is generalised to kernelised version for further boosting the performance. Experiments on two benchmark person re-identification datasets demonstrate that the approach clearly outperforms the state-of-the-art methods.

Occlusion is a challenging problem in real-time visual object tracking. Most state-of-the-art methods learn the inaccurate appearance of the target when it becomes occluded by other objects in the scene. To address this issue, a novel one-step backtracking (OB) tracker for occlusion detection is proposed, which backtracks to one previous frame and detects occlusion by comparing the tracking result with OB result in each frame. An adaptive learning model update scheme is further proposed by computing the peak-to-sidelobe ratio of the response maps to improve the tracking performance. Experiments on several benchmark sequences show that the proposed tracker outperforms state-of-the-art approaches and achieves real-time visual tracking.

In the variable tap-length algorithm, fast-convergence rate and small steady-state fluctuation of the tap-length are two important criteria to evaluate performance of the algorithm. Furthermore, the simplicity and robustness to the noise are the key points for the algorithm to be applied in practise. Along this line, a very simple variable tap-length algorithm is processed where the adaptation rule for fractional tap-length is modified by incorporating strategy of limiting the amplitude of difference between squared output error and squared segmented error. Only at a slight cost of computational complexity, the proposed algorithm can achieve both small steady-state fluctuation and fast-convergence rate of the tap-length under a high stochastic Gaussian noise condition (signal-to-noise ratio = 0 dB) or a deterministic impulsive noise condition.

A method for denoising accelerometer data based on the L2-norm total variation (LTV) algorithm is presented. In order to collect accelerometer data, a wireless accelerometer sensor was developed that is directly connected to a central node. By benefiting from the LTV algorithm, the obtained signals from the accelerometer are denoised. The proposed method is tested by denoising in different accelerometer signals and the results are evaluated by signal-to-noise ratio and power spectral density functions of the signals. The obtained results reveal that noise reduction has been implemented satisfactorily. Hence, the measurement accuracy of accelerometer signals for the proposed method have improved ∼4–10% than other the three low-pass filters including Savitzky–Golay, equiripple-pass-band and Butterworth.

A novel 3D frequency selective structure (FSS), exhibiting bandpass filtering response with high frequency selectivity, is presented. In each unit cell, multiple resonators are constructed to provide multiple transmission zeros/poles. By establishing an equivalent circuit model, it is obtained that the transmission poles in the passband are produced by a short-circuited resonator and an open-circuited resonator, and the transmission zeros close to the passband are attributed to the fundamental and spurious resonant frequencies of another short-circuited resonator. To implement it in high frequencies, multi-layer printed circuit board technology is introduced, where several replacements are carried out. The measured results show good agreement with simulations. Furthermore, the proposed FSS exhibits stable performance with incident angles increased from 0 to 50°.

Absolute added correlative coding with eight levels has been proposed and demonstrated numerically at bit rates of 30 and 60 Gbps back-to-back, and up to 75 Gbps over 2000 and 3000 m standard single-mode fibre using a single-drive multiple quantum-well Mach–Zehnder modulator. The transmission performance is compared with the conventional eight-level pulse amplitude modulation.

Excellent performance of custom technology SPAD detectors have been widely demonstrated in recent years. Low-jitter timing measurements with these detectors require front end electronics able to sense the avalanche current at a very low level when the multiplication process is still confined in a very small area around the photon absorption point. Best in class results (35 ps full width at half maximum) have been obtained with discrete circuits not suitable to be used in densely integrated systems of SPAD arrays required by modern demanding applications. A new fully integrated front end able to read out the avalanche current with a timing jitter as low as 32 ps and suitable to be exploited with SPAD arrays is presented.

A low pump threshold passively harmonic mode-locked fibre laser is demonstrated. The key component is a chemical vapour deposition grown graphene saturable absorber to enable higher order harmonic mode-locking (HML) of the fibre laser with good output noise characteristics. With a relatively low pump power of 100 mW, the fibre laser generates ∼1 ps soliton pulses at the 21st order of HML with 40 dB of super-mode noise suppression.

An application of charge-coupled device (CCD) linear sensor and laser diode in an optical tomography (OPT) system is presented. The measurements are based on the final light intensity received by the sensor. The aim is to analyse and demonstrate the capability of laser with a CCD in an OPT system for detecting transparent objects in crystal clear water. The image reconstruction algorithms used were filtered images of linear back projection algorithms. These algorithms were programmed using LabVIEW programming software. Experiments in detecting transparent hollow straw were conducted. Based on the results, statistical analysis was performed to verify that the captured data were valid compared with the actual object data. The object's characteristics such as diameter also are observed. In conclusion, a non-intrusive and non-invasive OPT system that can detect transparent objects in crystal clear water is successfully developed.

Integrated modulators are being intensely investigated and became potential candidates for the fundamental building blocks of next generation silicon-based front-end transceivers. Although suitable optical performance has been demonstrated in several works, theoretical models for the appropriate driving conditions of the micro-ring modulators are rarely explored. The carrier concentration fundamentally determines the refraction index of the pn junction of the modulator and to accelerate charge injection/extraction a pre- and de-emphasised driving voltage technique has been widely and successfully applied. Here we present a mathematical model where shooting amplitude and duration are considered with an optimised power consumption analysis. The model can be applied for both NRZ and RZ modulation formats.

For three-phase power system, the synchronous reference frame (SRF) phase-locked loop (PLL) is probably the most widely used synchronisation technique under ideal grid condition. However, the presence of dc-offset causes fundamental frequency oscillations errors in estimated phase. To deal with this problem, delay signal cancellation (DSC) operator is utilised in SRF-PLL in recent published literature at the cost of slowing down the dynamic behaviour. The aim is to propose a rapid dc-offset rejection method in three-phase PLL for grid synchronisation. With the employment of modified DSC operator, the dynamic performance of the conventional DSC-based PLL is improved. The effectiveness of the proposed method is confirmed through simulation results.

A single-stage AC–DC voltage regulator is proposed to enhance the power efficiency while at the same time reducing the design complicity of the entire system. Unlike the traditional two-stage AC–DC regulator, a pulse-width modulation control algorithm is integrated to switch the working mode of an active rectifier between a charging mode and a zero mode to maintain the output voltage at 5 V. This in turn efficiently eliminates the need for a DC–DC converter following the rectifier. Besides, a coupled full-bridge active rectifier with high speed comparator dramatically reduces the power loss of the circuit. Experiment results using a 0.35 µm technology and a PCB circuit demonstrate the advantages of the proposed design.

LLC converter is widely used in various applications due to its simple structure and zero voltage switching capability. To achieve high efficiency, LLC converter is usually designed to operate near the resonant frequency over the entire load conditions. However, a constant core loss of the main transformer due to the constant frequency operation has a bad effect on the efficiency in a light load condition where the core loss dominates the total loss. Therefore, it is essential to reduce transformer core loss in order to improve light load efficiency. Adapting asymmetric pulse-width modulation (APWM) in a half-bridge LLC resonant converter with voltage doubler rectifier for improving light load efficiency has been proposed. By adapting APWM, the core loss can be reduced dramatically in the light load condition, because both the switching frequency and the flux swing of the transformer are reduced. Furthermore, the proposed method does not affect the design of the converter. The experimental results with 400–250 V input and 100 V/2 A output prototype converter support the effectiveness of the proposed method.

Piezoelectric microgenerator is an incredible method which makes a self-powered wireless sensor node. It is a process of converting ambient energy into electrical energy. Flexible microgenerator goes well with many natural curved, rough and arbitrary surfaces such as human bodies, organisms, clothes and structure surfaces. Zinc oxide and polymer have been used as piezoelectric material and substrate, respectively, for biocompatible device. The harmonic analysis was carried out using finite element method (FEM) tool to examine the effect of the electrodes on the output voltage. Microgenerators with different electrodes were fabricated and examined their performance. Traditional parallel plate metal electrodes (PPEs) are prone to cracks and internal defects on bending or stretching, thus mesh electrodes (MEs) has been proposed. Copper MEs based microgenerator has performed at par. Open-circuit electric potential of 2.8 V_PEAK, 435 mV_RMS for ME against electric potential of 2.3 V_PEAK, 430 mV_RMS and 0.9 V, 340 V_PEAK, 40 mV_RMS for interdigitated electrodes (IDEs) and PPE, respectively, were recorded. Design, fabrication, electrical characterisation and comparative evaluation of microgenerator with three different electrodes are presented.

Sector determination for a normalised space vector pulse width modulation (SVPWM) scheme is proposed for four-switch three-phase (FSTP) voltage source inverter (VSI) by using already available stationary reference frame stator voltages without requiring complex trigonometric calculations. The proposed method has been simulated by using MATLAB/Simulink and implemented using a VSI with a TMS320F28335 floating-point digital signal processing. Simulation and experimental results show the feasibility and effectiveness of the proposed SVPWM algorithm for FSTP inverter.

A new self-compensation technique is proposed for eliminating subharmonic oscillation and chaotic regimes in dc–dc switching converters under peak current mode control. The proposed method extracts a control signal from the error between the inductor current and a suitable reference and does not require an external signal generator as in the conventional ramp compensation scheme. The analytical expressions of the control domain using Filippov method are obtained. Simulation results show that the proposed technique can be implemented using standard analogue devices and can effectively eliminate subharmonic and chaotic oscillations and can ensure a stable operation for a wide range of the duty ratio.

A novel method for buried target extraction, the active phase compensation technique is proposed. The range migration algorithm (RMA) is the conventional method for synthetic aperture radar (SAR) image reconstruction, but if targets exist in different media, identification of the target can be difficult because of losses and the significant reflection from the boundary face. In this regard, the matrix pencil method is utilised to actively find the boundary point and buried target responses. Then, the reflection effect can be eliminated, and range cells corresponding to estimated target responses can be compensated by applying newly created compensation functions. It improves the detection accuracy of buried targets. Finally, experimental results demonstrated that the proposed technique performs better than the classic RMA.

A huge limitation of the correlation analysis in existing scatterer model is that only uniformly distributed scatterers are considered ignoring the variability of scattering intensity in the real situation. In fact, each part of the target has a diverse scattering architecture, thus, the scattering intensity varies with the target surface structure. To make a better equivalent of the real target, the echo correlation coefficient is studied for scattering model which has several variable dominant scatterers to make an equivalent of different scattering architecture in spatial–frequency diversity MIMO radar. The proposed analysis enhances the authenticity of scattering model and expounds the correlation coefficient varying with the scattering intensity and the position of each dominant scatterer. Simulation results are presented to validate the proposed analysis.

Synthetic aperture ladar (SAL) is analogous to the synthetic aperture radar (SAR) but works at wavelength 10^4–5 times shorter. SAL has the potential for much finer resolution than SAR. Due to the shorter wavelength used for SAL, the platform vibration would induce high-frequency and large-amplitude phase errors during the data collection. Direct using of the conventional imaging algorithms to SAL data suffers from performance degradation. To address this problem, an effective imaging method based on subaperture phase gradient autofocus (PGA) and normalised cross correlation (NCC) is proposed for airborne SAL data. First, the length of subaperture is determined according to the criterion that the coherent processing interval (CPI) is shorter than half of the vibration period. Then the phase history data (PHD) is formatted into a few subapertures and the PGA is employed to estimate the phase errors in each subaperture. After the compensation of the phase errors, each subaperture image is focused with the conventional imaging algorithm. Finally, a recombination of the subapertures is performed based on the NCC. The proposed method is verified by processing the real SAL data collected by strip-mode with the demonstrator system built at Institute of Electronics, Chinese Academy of Science.

A novel reconfigurable phase inverter architecture allowing frequency-switchable is proposed. Interdigital striplines, metallic via holes, and the defected ground structure are used to obtain 180° phase inverter. The switchable frequency is controlled by the length of the slot-line on the defected ground which can be changed by PIN-diodes and a single control voltage. For verification, the simulated and measured results of switchable frequency at 900 MHz and 1.6 GHz phase inverter implemented on microstrip are shown.

In cellular-based public safety networks, user equipments (UEs) located in coverage area of active cells are able to act as relay UEs (RUEs). These RUEs provide cellular services to isolated UEs (IUEs). Due to mobility of both an IUE and a RUE, a link between them may be disconnected. Thus, it is necessary to newly establish a link between the IUE and another RUE. Unfortunately, it may cause that packets sent by previous RUE to be lost during the link re-establishment procedure. An efficient sidelink re-establishment procedure is proposed to reduce link re-establishment set-up delay. The performance of the proposed method compared with the conventional scheme used in 3rd Generation Partnership Project is evaluated. The proposed scheme shows better performance than the conventional scheme in terms of signalling overhead and set-up delay for sidelink re-establishment.

The probability density function and cumulative distribution function of the received signal-to-noise ratio (SNR) and the received signal-to-interference ratio (SIR), for interference-limited systems is derived, at the nth nearest neighbour node in a Poisson point process wireless random network. The analytical expressions are given in terms of the Meijer G-function and reveal the impact of node spatial density, transmit power, interference power, and path-loss exponent on the connectivity probability of a broadcast wireless transmission. The analytical results are validated with computer simulation.

A joint power and rate optimisation for multihop relay networks adopting different hybrid automatic repeat request (HARQ) schemes are investigated. Specifically, Type-I HARQ, chase-combining-based HARQ and schemes without HARQ are considered with practical system parameters. The optimisation problem is to adjust transmission power and rate of each node to maximise spectral efficiency under the limitations of total power consumption. However, this problem is not always mathematically tractable for three HARQ schemes. Hence, low-complexity iterative algorithms are proposed to obtain the optimisation strategies. Numerical results demonstrate that joint optimisation strategy outperforms conventional separate optimisation strategies significantly. The impact of the path loss conditions is also investigated. It is found that performance improvement increases with increase in link unbalance.

The level of protection against thermal hazard of the current RF EM field (EMF) exposure limits is estimated at the transition frequency where the basic restrictions change from specific absorption rate to power density. It is shown that the calculated steady-state temperature increase in the skin generated by a nearby dipole transmitting at maximum power to meet compliance with the EMF limits presents a significant discontinuity at this frequency. The results suggest that for exposure to limited areas of the body at frequencies where basic restrictions are provided in terms of power density, the currently existing exposure guidelines need to be revised. These findings might have large implications on the development of future radio access technologies operating at the millimetre wave.