A balun designed on laminated epoxy PCB to measure inductive ultra-high-frequency-balanced antennas is presented. Its objective is to minimise the reflection coefficient at its unbalanced input when the antenna is connected to its balanced output. This improves the accuracy in the posterior extraction of the antenna parameters from the measurement of its reflection coefficient. Theoretical considerations, design parameters and experimental results with an evaluation antenna are shown.

A novel Zeonex based porous fibre is proposed for biomedical imaging and polarisation preserving applications of terahertz waves. The standard finite element method is used to simulate the propagation characteristics of the fibre that shows high numerical aperture of 0.48, high birefringence of 0.039 and a flattened dispersion of 1.07 ± 0.05 ps/THz/cm. In addition, the fibre also possesses low effective material loss and negligible confinement loss in the terahertz frequency band.

A new all-digital delay-locked loop (ADDLL) using successive-approximation register (SAR) control scheme is presented. The proposed circuit architecture can effectively perform the per-bit acquisition within one clock cycle. Therefore, the divider for generating internal SAR clocks can be further removed to achieve fast-locking capability. Meanwhile, the harmonic-locking problem that often occurs in a wide range of operating frequencies is also eliminated. The test chip is designed and verified with CMOS 0.18 μm technology. The measured acquisition cycles for all operating frequencies (100–800 MHz) are constant as 11 when a 10-bit digital-controlled delay line is employed. The rms/peak-to-peak jitters at the highest and lowest frequencies are 0.775/5.73 and 1.08/8.27 ps, respectively. The chip core occupies an active area of 0.015 mm² and consumes 9.4 mW at 800 MHz.

Solid state drives (SSDs) achieve a significantly better performance than hard disks by internally implementing channel level, chip level, and die level parallelism. However, the plane level parallelism has not been sufficiently exploited, because of the constraint that the target pages of the planes must be in the same location. To overcome this constraint, a policy that enforces the multi-plane operation by matching the position of the target pages while wasting clean pages is proposed. However, this policy excessively increases the number of block erasures, which leads to reducing the stability and lifetime of the SSD. To solve this problem, this Letter proposes a policy that determines whether to perform the multi-plane operation considering the number of wasted clean pages. The performance evaluation using representative server workloads shows that the proposed policy improves an average performance by up to 28.82% over the policy that does not perform the multi-plane operation, without significantly increasing the number of block erasures.

An area-efficient tri-level switching scheme is proposed for the successive approximation register (SAR) analogue-to-digital converters (ADCs). Unlike existing tri-level scheme, the proposed switching scheme is based on a new third reference voltage V _aq which is a quarter of the reference voltage V _ref. With reusing the least significant bit capacitors in the last two bits generation, the proposed switching scheme achieves 87.5% less number of unit capacitors and 96.48% less switching energy over the conventional scheme.

Electrodynamics theory tells that EM waves are generated from accelerated charged particles. Conventional radiators such as antennas are understood to emit waves because of the current's distribution and accumulation in the capacitor, where electrons are accelerated. In MEMS mechanisms, charges can be accelerated by the mechanical motion, which suggests that an MEMS structure can also be a radiator. The electrodynamics to theoretically analyse the EM wave radiation from MEMS is used. During the electrostatic nonlinear pull-in instability MEMS, where the electrostatic gap has become narrower than the 2/3 of the initial gap, the distributed charges are accelerated at a very high rate so as to generate significant power radiation in the form of EM waves. The MEMS's mechanical accelerations are analysed to calculate the transient radiations in both spatial and frequency domains.

A method is presented for accurately estimating 2D and 3D human poses by simultaneously performing 2D pose denoising and 3D pose reconstruction from noisy 2D human pose sequences. The proposed approach globally modifies the input 2D poses that are locally estimated by recent convolutional neural network-based methods. The denoised 2D poses are efficiently converted into 3D poses in a bottom-up manner using a feed-forward network rather than by optimisation, which is frequently used in existing methods. The proposed denoising and reconstruction network is used with existing 2D human pose estimators to provide state-of-the-art 3D human pose estimation results for large-scale real datasets.

An inductorless 13 Gbit/s analogue equaliser with an additional low-frequency equalisation (LFEQ) to counter the low-frequency channel losses is presented. An active feedback topology for the proposed equaliser together with negative capacitance circuit is used to extend the bandwidth to compensate a 15 dB channel loss at Nyquist. The LFEQ improves the measured data jitter of the conventional equaliser from 0.41 to 0.12 UI, for a pseudorandom binary sequence of 2³¹ − 1. The proposed prototype was implemented in 65 nm CMOS, occupying active area of merely 0.058 mm². It exhibits a power efficiency of 1.07 mW/Gitb/s under a supply voltage of 1.2 V and a BER < 10⁻¹².

The blockage is a tough hurdle for millimetre-wave (mmWave) unmanned aerial vehicle (UAV) communications. In this Letter, the authors propose an angle domain channel transmission scheme for mmWave hybrid UAV communication with blockage. Firstly, they investigate the angle domain channel transmission of mmWave UAV communication systems with massive array antennas. Then, they solve the blockage problem through the multi-UAV coordination. Specially, they provide a practical user scheduling algorithm to maximize the achievable sum rates. Finally, simulation results are provided to show the effectiveness of the proposed method.

The method proposed in this Letter selects a feature subset that preserves the data quality in the viewpoint of information theory. Using an efficient information-theoretic evaluation, the proposed method identifies the final feature subset significantly faster than conventional methods.

In general, most of the previous secret sharing schemes involve a secret dealer and a number of participants. The dealer generates a secret and then distributes the secret shares to the participants in a centralised manner, which may lead to the data tamper problem. A verifiable secret sharing scheme without dealer on vector space access structures over bilinear groups is presented. In particular, each participant can act as a ‘dealer’ and the secret in the proposed scheme is a random element generated by all the participants from a bilinear group. In addition, the performance of the proposed scheme in terms of security and computing complexity is analysed in detail and compared it with that of the scheme by Zhang and Zhang. The results show that the proposed scheme performs better in terms of computational cost.

An efficient acquisition method is proposed for high sensitivity and fine Doppler frequency estimation for direct-sequence spread spectrum signals. The proposed method first refines the Doppler frequency after a parallel code-phase search via triangle fitting of the cross-ambiguity function. Then, the information of amplitude and frequency before and after the frequency refining is used to exclude the false alarm. Compared to traditional acquisition methods, the proposed method has higher sensitivity and Doppler frequency estimation accuracy. Simulation results verify the validity of the proposed method.

A simple and efficient linearisation front-end circuit for giant magneto-resistance (GMR) sensors are presented. This circuit essentially uses only a single opamp to linearise the (non-linear) GMR sensor output. A novel methodology that places an active GMR element, present inside the GMR sensor, in the feedback loop of the opamp is employed for linearisation. Initial validation of the front-end is performed using simulation and emulation studies. Then, the front-end, fabricated on a printed-circuit board, is interfaced with a GMR sensor. Experimentation showed output non-linearity is around 0.6%. The proposed front-end possess merits, like, low component-count and minimal error, no requirement of expensive amplifiers or matched resistors for linearisation, fast response, over the existing methods.

A DC-16 GHz track-and-hold amplifier (THA) using 0.15-μm enhancement-mode GaAs pseudomorphic high-electron mobility transistor process is presented. A switched source follower (SSF) track-and-hold (T/H) stage is modified to enhance the sampling rate and linearity. The input-dependent timing jitter is highly reduced using the modified topology as compared to the conventional SSF T/H stage. Moreover, the even harmonics are successfully suppressed using the differential topology, and the spurious-free dynamic range (SFDR) and total harmonic distortion (THD) are improved. To widen bandwidth (BW), the input and output buffers are designed using the distributed amplifier and source follower, respectively. With a sampling rate of 13.5 GS/s, the proposed THA features a measured 3-dB BW of 16 GHz, an SFDR of 46 dB, and a THD of −45 dB.

A novel dual-band substrate integrated waveguide (SIW) bandpass filter (BPF) based on complementary split-ring resonators (CSRRs) is proposed. It consists of an SIW dual-mode cavity loaded by two additional CSRRs on its top layer. Both TE₁₀₂ and TE₂₀₁ modes in the cavity can be excited by the proper positions of the feeding lines. Two additional CSRRs are etched on the top layer coupled with the TE₁₀₂ and TE₂₀₁ modes, respectively, to achieve the dual-frequency operation. Four transmission zeros are generated in the vicinity of the passbands to improve the selectivity. To validate the design concept, a dual-band SIW BPF operating at 7.89 and 8.89 GHz is designed, simulated and measured. The measured results are in good agreement with the simulations.

The high-precision time synchronisation is of vital importance in the modern communication, navigation system and weapon system. The microwave time transfer method is adopted to resolve the time synchronisation problem. After expounding the principle and system composition of the method, the microwave time transfer system has been constructed. First, the measurement of board-level and system was conducted. The transfer bandwidth in the experiment via microwave channel is 10 Mb. The results show that the jittering of retrieval signals via microwave channel is <4 ns. Then the microwave transmission experiment of 23 km was carried out. The results show that RMS error of time signal is <2 ns and the error between the forward and backward directions is <4 ns.

A reconfigurable switched capacitor converter (SCC) topology with nine/ten CMOS switches and two flying capacitors is presented. It is capable of accepting two input sources simultaneously with an input voltage in the range of 1–2.5 V and delivers the output for 15 conversion ratios. The proposed SCC can drive a load current ranging from 10 μA to 10 mA at an open loop efficiency of >90%. One of the important applications of the proposed converter is the utilisation of photovoltaic (PV) or the combination of PV and other direct current sources. The regulation of the output voltage can be achieved either by changing the voltage conversion ratios or using variable switching frequency.

Current vector control of a resonant-type wireless power transfer system with 2D transmitting (Tx) coils is presented. The equivalent circuit model between two Tx and one receiving coils is derived in d–q coordinates. The control method to obtain the maximum power transmission efficiency is proposed. The experimental results are provided to verify the proposed control method.

The dual-buck full-bridge grid-connected inverter (DFGI) is well known as its no shoot-through problem, high efficiency and high reliability, but the common-mode leakage current exists in the positive half cycle. To solve the problems of common-mode leakage current of the conventional DFGI, a new DFGI topology is proposed. The corresponding modulation strategy is presented. Meanwhile, on the basis of the theoretical analysis, it can eliminate the common-mode leakage current of conventional DFGI. The experimental results prove the validity of the theoretical analysis.

Here, we propose a three-phase cyclic switched-capacitor step-down DC–DC regulator, which enhances output current while using the same total flying capacitance and keeping the same ideal power conversion efficiency as the conventional topology. Dual output voltages of 1.5 and 3.0 V using conversion ratios of 1/3 and 2/3 are obtained with a 5 V input voltage. The theoretical normalised output current (I _norm) is 33% higher than that of the conventional topology. The measured I _norm reaches 0.428 A/(F ·Hz) with 1 nF on-chip flying capacitors (C _f) at a switching frequency (f) of 20.8 MHz using 0.25 μm CMOS technology.

A variable on-time (VOT) control strategy for boundary conduction mode (BCM) single-ended primary inductor converter (SEPIC) power factor correction (PFC) converter with high power factor (PF) and low total harmonic distortion (THD) is proposed. By utilising output voltage and input voltage to modulate the turn-on time of the switch of BCM SEPIC PFC converter, the unity PF and lower THD can be achieved. The operating principles of the VOT controlled BCM SEPIC PFC converter are analysed. The experimental results based on 100 W prototype demonstrate that the PF and THD of proposed VOT controlled BCM SEPIC PFC converter are better than those of traditional BCM SEPIC PFC converter.

The interpolation method has been employed in non-integer-order moments estimators obtained in a previous work for the parameters of compound-Gaussian clutter model with inverse Gaussian texture (CGIG). Closed-form parameter estimators for the CGIG distributed clutter are derived with no special functions. These are achieved after a simple combination of three basic expressions: non-integer positive moments, non-integer negative moments and Bessel recurrence relation. Simulation results show that the derived estimators are well suited for multilook data and have a comparable accuracy as well as the numerically solved maximum-likelihood approach, but they are much simpler and faster to compute

In this Letter, the estimation of the presence, position, and posture of a device-free target is addressed through a multi-resolution strategy that applies a virtual zoom on the information content of the channel state information measured by a single WiFi link. A series of binary classifiers are trained to estimate multiple location-based features of the target from the same measurement. Preliminary experiments point out the feasibility to estimate high-resolution features such as the target posture even in very large investigation domains, passing through the estimation of the target presence and position. A robust and ubiquitous wireless sensing is obtained with failure rates lower than 2.5% in the three considered resolution steps.

This Letter proposes a cooperation policy between a macrocell and a hybrid access femtocell in an underlay heterogeneous network to improve the achievable data rate of an indoor macrocell user (MU) through time sharing access of the femtocell service together with mitigating cross-tier interference through price-based power control. Through numerical examples it is proved that the authors’ proposed cooperation policy is more beneficial to the macrocell not only for providing a higher achievable data rate for its MU but also for earning a higher revenue compared with the incentive-based cooperation policy proposed earlier without much degradation of the achievable data rate performance of any associated femtocell user.

A novel impedance transformer (IT), which transforms different terminations at multiple bands is reported. This transformer is especially suitable for extremely low and high impedances. By utilising the impedance buffer method and introducing ladder networks, this IT is generalised and is available to arbitrary number of bands theoretically. For verification, a quad-band prototype is fabricated and measured. The results show good agreement with the design expectations.