A miniature water patch antenna using high-permittivity liquid substrate is demonstrated. The utilised liquid substrate is ethyl acetate, which is an optically transparent liquid with permittivity of 7.8 over microwave frequencies. It turns out that when using ethyl acetate as the middle substrate, the diameter of the circular water patch can be decreased by 48% compared with the case using air as the middle substrate, and a wide bandwidth of 36% can be obtained. The results show that the ethyl acetate is an optional candidate to realise a compact transparent antenna.

This Letter presents an irregular pentagonal patch array antenna with a multilayer structure for dual-band and multimode orbital angular momentum (OAM) generation. An irregular pentagonal patch antenna with U-shaped slots resonating at different frequencies is designed as the array's element. The proposed antenna array consists of two uniform circular microstrip antenna arrays and two phase-shifting feeding networks. It can be used to generate OAM mode l = − 1, 1 at 3 GHz and OAM mode l = −2, 2 at 6 GHz. The simulated near-field phase distributions images of different OAM modes are obtained, which have verified the OAM generation. This proposed array antenna has the possibility to generate a total of six different OAMs in three frequency bands, by changing the number of array elements and optimising the irregular pentagonal patch antenna. This design may provide a new idea for the generation multimode vortex electromagnetic wave.

A counteracting dither technique is proposed to remedy the bit-weight error issue in pipeline analogue-to-digital converters (ADCs). A capacitor is added to the traditional comparator dither scheme. By switching the added capacitor, the residue swing increment due to comparator dither is counteracted, thereby greatly relaxing the design requirement of the residue amplifier. Behaviour-level simulation results show that the spurious-free-dynamic-range and the signal-to-noise-and-distortion-ratio are improved from 59 and 52.8 dB to 102.7 and 85 dB after calibration in a 14-bit ADC, respectively.

This Letter proposes a second-order bandpass ΔΣ ADC using a pipelined successive-approximation-register (SAR) ADC as an internal quantiser. The second-order bandpass noise-shaping is achieved by utilising the residue signal after SAR conversion and inherent delay existing in a pipelined structure. The proposed ADC can show very high resolution even with low-order noise-shaping and low oversampling ratio. Also, it shows good energy efficiency and a high sampling rate due to the use of a pipelined SAR ADC as a quantiser.

Stochastic computing offers an area-efficient solution for power-greedy computations in error-resilient applications such as image processing. However, stochastic computing produces only approximated results and suffers from long latency especially for multiplication. The authors present a multiplier design technique for stochastic computing which guarantees exact output and has latency in the order of 2 ^N (N = input precision), utilising the counter for unary-to-binary conversion. Compared to state-of-the-art deterministic methods the proposed design is faster by a factor of 2 ^N . Besides, the area of proposed design scales up in proportion to N instead of N ², as opposed to conventional binary multipliers. The design technique can be further extended for multiple inputs and parallel computing, Extensive mathematical analysis and simulation results are presented for each variation throughout this Letter.

The state-of-the-art convolutional neural networks (CNNs) have been widely applied to many deep neural networks models. As the model becomes more accurate, both the number of computation and the data accesses are significantly increased. The proposed design uses the row stationary with network-on-chip and the fast convolution algorithm in process elements to reduce the number of computation and data accesses simultaneously. The experimental evaluation which using the CNN layers of VGG-16 with a batch size of three shows that the proposed design is more energy-efficient than the state-of-the-art work. The proposed design improves the total GOPs of the algorithm by 1.497 times and reduces the on-chip memory and off-chip memory accesses by 1.07 and 1.46 times than prior work, respectively.

This Letter presents meaningful results that demonstrate the reduction of dimensionality by spiking neural networks (SNNs) on benchmarking data. This experimental scheme includes metaheuristics, namely, the artificial bee colony algorithm (ABC algorithm) for finding optimal conductance values in the SNNs. Therefore, the objective function in the used ABC algorithm leads the SNNs to compute the principal component analysis (PCA), efficiently. The eigendecomposition of the information drawn by the SNNs in the training phase is the base of the formulated objective function. In these experiments, the Izhikevich model represents the spiking neurons, which have biological plausibility with parameters for reproducing a uniform firing rate. The visualisation of clusters in the 3D PCA space, whose sample values are compared with the PCA function in Matlab, is also shown; this comparison demonstrates an acceptable error in the MSE sense.

When a wheeled mobile robot is travelling at high longitudinal velocities and turning, it may sideslip. Except for a few researchers, this issue has not received much attention. However, there is a high possibility that sideslip may cause danger, so the authors think this problem needs to be solved urgently. The mechanism of preventing sideslip is simple, which is to reduce the longitudinal velocity of the robot when turning. But, how to slow down is a question worth studying. To this end, they have proposed two schemes, but these two schemes have poor real-time performance and poor robustness to positioning errors, respectively. In order to solve the above problems, considering that the real-time and robustness of fuzzy control are very good, they propose a controller by combining robust control and model predictive control in this Letter. The fuzzy control is used to adjust the longitudinal velocity according to the state of the robot, and the model predictive control is used to achieve path tracking. According to the simulation results, the proposed fuzzy model predictive controller does have small errors, small sideslip, good real-time performance, and good robustness to positioning errors.

This Letter proposes a promising deep learning-based method for crack segmentation based on gated skip connection. The proposed gated skip connection enables the decoder layers to promote crack-aware feature representations from the encoder layers by applying high weights on the crack-relevant features that come from the encoder layers and lower weights for irrelevant features. Unlike the related methods, the authors do not apply any pre-processing or refinement steps to improve the crack segmentation results. The proposed method beats the state-of-the-art methods with an open benchmark database (IoU of 87.5).

In this Letter, the authors deal with ranking of keyword-combined searches in relational databases based on relevance to the user query, which they call KEYSIM searches. They formally define KEYSIM searches and propose a threshold-based method for efficiently processing KEYSIM searches. Their proposed method is the first one to find top-k results considering both numerical similarity and textual similarity. Through the experiments using five real and synthetic data sets, they show the efficiency and scalability of the proposed method.

A positive feedback gain-enhanced technique for power amplifiers has been introduced in this Letter. With the proposed circuit design method for optimal inductive feedback, a 180 GHz high-gain single-stage cascode power amplifier in a 130 nm SiGe process is implemented. The measurement results show a power gain of 10 dB and 20 GHz bandwidth with 110 mW dc power are achieved, and 6.5 dBm of output power referred to P _1dB and 3.5% collector efficiency are attained. The chip area of the power amplifier is only 0.50 × 0.48 mm².

The authors demonstrate integrated 1D optical phased arrays (OPAs) for wide-angle 2D beam-steering. The 2D OPA consists of 16 1D transversal steering OPAs whose radiators have different grating periods, to assign different longitudinal angles. The transversal steering of each OPA is performed by the phase control of the p-i-n electro-optic phase shifter array. The 1D transversal steering OPAs operate serially, changing the longitudinal radiation angle. The grating radiators were designed with an array pitch of 2 μm, and a varying period in the range of 610–710 nm. The entire 16 × (1 × 16) OPAs were integrated into a small area of 26.5 mm². The obtained transversal/longitudinal beam-steering range was 46°/44°, respectively, with a wavelength of 1560 nm, which enables wide 2D beam-steering.

A resonant converter with less voltage rating of power switches and wide voltage operation is investigated in this Letter for medium voltage applications. Four active switches and two split capacitors are adopted on the primary side to reduce the voltage rating on power semiconductors. The resonant converter is adopted in the converter to have a wide soft switching operation range. Two flying capacitors are used in the presented circuit to operate as the resonant capacitor and also to achieve voltage balance of two input split capacitors. The variable winding turns are used on the secondary side to overcome the problem of the limited voltage operation in the conventional resonant converter. If the input voltage is in the low-input voltage range, the low turns-ratio of the power transformer is used to increase the voltage gain of the resonant converter. If the input voltage is in a high-voltage range, then the high turns-ratio of the transformer is adopted to reduce the voltage gain. Thus, the proposed converter can achieve wide input voltage operation. Experimental results with a 0.8 kW prototype are provided to confirm the effectiveness of wide input voltage operation from 260 to 800 V.

A new simplified control scheme is proposed for AC–DC electrolytic capacitor-less converters operating in continuous conduction mode (CCM). The proposed method has a single-loop controller responsible for both regulation and power factor correction (PFC). In comparison with the two-loop conventional CCM current mode controller, the proposed scheme does not need a multiplier or extra sensors hence simplifying the control circuitry and its design procedures. Modelling of the closed-loop converter is addressed and experimental results are provided to show the feasibility of the control scheme.

In this Letter, the authors aim at solving the unbalanced current problem existing in the two-inductor high-voltage-gain converter and the turn-off delay control method is proposed to solve the issue. In the two-inductor high-voltage-gain converter, one of inductor current of the corresponding path could be increased to compensate the difference of two inductor current by extending turn-on time of the main switch, and therefore, the current balance is achieved. Moreover, the operating mechanism of the proposed method is described in detail. Analytical results indicate that the proposed method has no effect on voltage transfer gain of the converter. Finally, experimental results have been given to verify the theoretical analysis.

The simple linear iterative clustering (SLIC) is the most popular superpixel segmentation method for its simplicity and effectiveness. In this Letter, we propose an edge attention-based geodesic distance, which can be applied to the SLIC framework for polarimetric synthetic aperture radar image superpixel segmentation. Image edges are especially considered to generate superpixels with better boundary adherence property, while the computing burden does not increase. Specifically, the authors first detect image edges, then fuse the edge map and polarimetric dissimilarity, and finally define the geodesic distance based on the fused results. Experiments performed on real scene images demonstrate the superiority of the proposed distance in both qualitative and quantitative ways.

The future L-band geosynchronous synthetic aperture radar (GEO SAR) system will be inevitably affected by ionospheric scintillation. Due to the lack of the real system, it is necessary to achieve the scintillation-affected GEO SAR raw data for the research of influential mechanism and correction strategies. A method for the generation of scintillation-affected GEO SAR raw data is proposed that utilises the reverse backprojection (ReBP) to efficiently and accurately modulate the scintillation transfer function on GEO SAR signals. A simulation experiment for a real SAR scene from one of the ALOS-PALSAR observation is operated in case of the current inclined L-band GEO SAR system configuration. The simulation takes less time by using the ReBP, compared with the existent method, and shows the speckle-like phase error similar to the injected scintillation phase error, which validates the nice efficiency and accuracy of the proposed methodology.

Low-dielectric constant (low-k) material is critical for advanced FinFET technology parasitic capacitance reduction to enable low-power and high-performance applications. Silicon Oxycarbonnitride (SiOCN) is one of the most promising low-k materials for FinFET gate sidewall spacer. The k value of SiOCN can be controlled in the range of 4.1–5.2 by modifying the chemical contents during the deposition process. However, the integration of SiOCN with k value lower than 5.2 for advanced FinFET technology faces substantial challenges associated with the material damage from subsequent manufacturing processes. Here, the authors demonstrate a hybrid low-k spacer scheme on a fully integrated 7 nm FinFET technology platform, in which SiOCN with k value of 4.5 was successfully integrated along the sidewalls of the gate electrode as spacer while retaining the structural integrity and dielectric properties. Device characterisation on the hybrid low-k spacer scheme (k = 4.5) demonstrated 12/11% reduction in P/NFET overlap capacitance (C _OV) and 3% reduction in ring oscillator effective capacitance (C _EFF) in comparison to the baseline reference using SiOCN with k value of 5.2 as spacer. Furthermore, reliability characterisation confirmed the dielectric breakdown voltage (V _BD) and leakage current (I _LKG) of the hybrid low-k spacer (k = 4.5) were comparable to the baseline reference (k = 5.2), meeting the technology requirements.

In many practical applications, systems and signals show energy concentration in a few coefficients. This prior knowledge can often be incorporated into algorithms designed for tasks such as compressive sensing and system identification. This Letter proposes a new least mean square (LMS)-based algorithm that exploits the hidden sparsity of the system that the adaptive filter intends to estimate. The algorithm minimises the -norm of a linear transformation of the coefficient vector, using the minimum distortion principle. Simulation results demonstrate good performance of the proposed algorithm with respect to the LMS algorithm. In addition, a stochastic model of the advanced algorithm is proposed, which provides accurate mean-square deviation and mean-square error predictions.

This Letter presents a novel technique for establishing a robust communication link to a spinning un-stabilised small satellite such as a CubeSat. The authors propose a system that involves a multimode excited planar circular array radio combined with a 360° phase shifter that can electronically track the spinning CubeSat antenna and establish a communication link. The transmitter comprises a mode-generating Rotman lens and a circular array of microstrip patch antennas. The authors’ proposed approach combines two spatially orthogonal modes of the circular array. They first present the system architecture, then they design and realise a proof-of-concept experimentally validated module operating in C-band at 5.8 GHz.