Robustness of Exact p‐Controllability and Exact p‐Observability to q‐Type of Perturbations of the Generator

In Mei and Peng, Systems & Control Letters, 59 (2010) 470–475, the authors have proved in general setting that p‐admissibilities of control operators and observation operators are invariant to any q‐type of perturbations of generator of C₀‐semigroups on Banach space. In this paper, under the p‐admissibility invariance premise, the robustness of the exact p‐controllability as well as the exact p‐observability to q‐type of perturbations is verified.     

Models and solution methods for the uncapacitated r‐allocation p‐hub equitable center problem

Hub networks are commonly used in telecommunications and logistics to connect origins to destinations in situations where a direct connection between each origin–destination (o‐d) pair is impractical or too costly. Hubs serve as switching points to consolidate and route traffic in order to realize economies of scale. The main decisions associated with hub‐network problems include (1) determining the number of hubs (p), (2) selecting the p‐nodes in the network that will serve as hubs, (3) allocating non‐hub nodes (terminals) to up to r‐hubs, and (4) routing the pairwise o‐d traffic. Typically, hub location problems include all four decisions while hub allocation problems assume that the value of p is given. In the hub median problem, the objective is to minimize total cost, while in the hub center problem the objective is to minimize the maximum cost between origin–destination pairs. We study the uncapacitated (i.e., links with unlimited capacity) r‐allocation p‐hub equitable center problem (with) and explore alternative models and solution procedures.     

Global adaptive finite‐time stabilization for a class of p‐normal nonlinear systems via an event‐triggered strategy

This article addresses the problem of global adaptive finite‐time control for a class of p‐normal nonlinear systems via an event‐triggered strategy. A state feedback controller is first designed for the nominal system by adding a power integrator method. Then, by the skillful design of adaptive dynamic gain mechanism, a novel event‐triggered controller is constructed for uncertain nonlinear system without homogeneous growth condition. It is proved that the global finite‐time stabilization of p‐normal nonlinear systems is guaranteed and the Zeno phenomenon is excluded. Finally, two examples are presented to indicate the effectiveness of the proposed control scheme.     

Peripheral circuit designs using low‐temperature p‐type poly‐Si thin‐film transistors

Abstract— P‐type low‐temperature (450°C) polycrystalline‐silicon thin‐film‐transistor circuits for peripheral driver integration in active‐matrix displays are proposed and verified. A low‐voltage (5 V) driven poly‐Si scan driver is designed by employing a level shifter and shift register. A source driver for six‐bit digital interface is proposed, and the building blocks such as latch, DAC, and analog buffer are described. The latch samples and holds the digital bits (D and D') without an output voltage loss. A new source‐follower type analog buffer is developed and exhibits a small offset deviation regardless of the V_TH variation of the buffer TFT. The simulation and measurement results ensure that the proposed circuits were successfully designed for p‐type panel integration.     

A 4‐bit ultra‐wideband complementary metal‐oxide‐semiconductor attenuator with low root‐mean‐square amplitude error

This article presents the 4‐bit ultra‐wideband complementary metal‐oxide‐semiconductor (CMOS) attenuator in a standard 0.18‐μm CMOS process. This design adopts switched bridge‐T type topologies for each attenuation bit. Based on insertion losses and input P_1‐dB considerations, the circuit performances can be optimized by the proper bit ordering arrangement. Therefore, the bit ordering 0.5‐4‐2‐1 dB is employed in the 4‐bit attenuator. Moreover, series inductors are added between each bit to further improve the input and output return losses. Measured results demonstrate that the attenuation range of the circuit is 7.5 dB with 0.5 dB step and the root‐mean‐square (RMS) amplitude error is between 0.11 and 0.13 dB from 3.1 to 10.8 GHz. The differences between simulated and measured RMS amplitude errors are less than 0.2 dB, which demonstrates the good agreement and feasibility of the design concept. The measured input P_1‐dB is 15 dBm at 5 GHz and the chip area is 1.12 mm² including all testing pads.     

Nanorod‐form ZnO‐homojunction ultraviolet light‐emitting diodes

Abstract— Ultraviolet (UV) light‐emitting diodes based on ZnO‐homojunction nanorods is reported. p‐type doping can be obtained from intrinsic (or close to) ZnO by introducing acceptors, such as P or As, using ion implantation followed by appropriate thermal annealing and dopant activation. Our approach provides a possible solution to p‐type doping of ZnO and ZnO‐homojunction light‐emitting diodes. It is interesting to note that this solution is offered in the form of nanorods.     

A new a‐Si:H TFT pixel circuit employing data‐reflected negative‐bias annealing for a stable and uniform AMOLED

Abstract— A new a‐Si:H pixel circuit to reduce the VTH degradation of driving a‐Si:H thin‐film transistors (TFTs) by data‐reflected negative‐bias annealing (DRNBA) is presented. The new pixel circuit compensates VTH variation induced by non‐uniform degradation of each a‐Si:H pixel due to various electrical stress. The proposed pixel circuit was verified by SPICE simulations. Although the VTH of the driving a‐Si:H TFT varies from 2.5 to 3.0 and 3.5 V, the organic light‐emitting diode (OLED) current changes by only 1.5 and 2.8% in the emission period, respectively. During the negative‐bias annealing period, the negative VGS is applied to the driving TFT by using its own data signal. It is expected that the VTH shift of the driving TFT can be effectively reduced and the VTH shift can be compensated for in our new pixel circuit, which can contribute to a stable and uniform image from an a‐Si:H TFT active‐matrix OLED.     

Poststress RF‐drifts of dual‐band LC VCO in 0.18‐μm CMOS technology

This article studies the RF‐property of a dual‐band voltage‐controlled oscillator (VCO). The designed circuit consists of a dual‐resonance LC resonator and a Colpitts negative resistance cell. The dual‐resonance LC resonator comprises a series‐tuned LC resonator and a parallel resonant resonator. The proposed VCO has been implemented with the TSMC 0.18 μm 1P6M CMOS technology. The VCO can generate differential signals in the frequency range of 3.0–3.37 GHz and 6.95–7.40 GHz with core power consumption of 10.08 and 10.24 mW at the dc drain‐source bias V_DD of 1.4 V, respectively. The die area of the dual‐band VCO is 0.485 × 0.800 mm². The circuit was operated at V_DD = 3 V for 8 h and significant drift in RF parameters was found. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:243–248, 2014.     

Output feedback finite‐time stabilization of a class of nonlinear time‐delay systems in the p‐normal form

This article investigates the finite‐time output feedback stabilization problem for a class of nonlinear time‐varying delay systems in the p‐normal form. First, a reduced‐order state observer is designed to estimate the unmeasurable state. Then, an output feedback controller is constructed, with the help of the finite‐time Lyapunov stability theorem, it is proved that the state of the resulting closed‐loop system converges to the origin in finite time. Two simulation examples are given to verify the effectiveness of the proposed scheme.     

Microwave analysis of SiGe heterojunction double‐gate tunneling field‐effect transistor through its small‐signal equivalent circuit

In this study, Si_0.5Ge_0.5 was used as a source junction material in a tunneling field‐effect transistor (TFET), which was analyzed using technology computer‐aided design (TCAD) simulation and a small‐signal non‐quasi static (NQS) equivalent circuit. The NQS equivalent circuit with additional tunneling resistance (R_tunnel) enables more accurate analyses. By using a de‐embedding process, small‐signal parameters in the intrinsic area were obtained. This process was used to analyze the resistance and capacitance in each section, the tendencies of the materials, and the voltage. The error between the NQS equivalent circuit and TCAD device simulation was within 1.9% in the 400‐GHz regime. A cut‐off frequency (f_T) of up to 0.876 GHz and maximum oscillation frequency (f_max) of 146 GHz were obtained.     

Bayesian inference‐based small‐signal modeling technique for GaN HEMTs

A new modeling methodology for gallium nitride (GaN) high‐electron‐mobility transistors (HEMTs) based on Bayesian inference theory, a core method of machine learning, is presented in this article. Gaussian distribution kernel functions are utilized for the Bayesian‐based modeling technique. A new small‐signal model of a GaN HEMT device is proposed based on combining a machine learning technique with a conventional equivalent circuit model topology. This new modeling approach takes advantage of machine learning methods while retaining the physical interpretation inherent in the equivalent circuit topology. The new small‐signal model is tested and validated in this article, and excellent agreement is obtained between the extracted model and the experimental data in the form of dc I–V curves and S‐parameters. This verification is carried out on an 8 × 125 μm GaN HEMT with a 0.25 μm gate feature size, over a wide range of operating conditions. The dc I–V curves from an artificial neural network (ANN) model are also provided and compared with the proposed new model, with the latter displaying a more accurate prediction benefiting, in particular, from the absence of overfitting that may be observed in the ANN‐derived I–V curves.     

PID Stabilization of Retarded‐Type Time‐Delay System

An analytical method is proposed to construct the stabilizing PID region of a retarded‐type time‐delay system, based on Pontryagin's results and a generalization of the Hermite‐Biehler theorem. It is shown that the stable region in the (k_i, k_d)‐plane is made up of some convex polygons for a fixed k_p, and the whole region in the (k_p, k_i, k_d)‐space is comprised of some polyhedrons, each of which is mapped onto a real used string. Additionally, a method for determining the feasible k_p‐intervals is given in this paper. Two examples are employed to illustrate and verify the construction procedure of the stabilizing PID region in detail.     

Solving the bi‐objective capacitated p‐median problem with multilevel capacities using compromise programming and VNS

A bi‐objective optimisation using a compromise programming (CP) approach is proposed for the capacitated p‐median problem (CPMP) in the presence of the fixed cost of opening facility and several possible capacities that can be used by potential facilities. As the sum of distances between customers and their facilities and the total fixed cost for opening facilities are important aspects, the model is proposed to deal with those conflicting objectives. We develop a mathematical model using integer linear programming (ILP) to determine the optimal location of open facilities with their optimal capacity. Two approaches are designed to deal with the bi‐objective CPMP, namely CP with an exact method and with a variable neighbourhood search (VNS) based matheuristic. New sets of generated instances are used to evaluate the performance of the proposed approaches. The computational experiments show that the proposed approaches produce interesting results.     

Silicon‐nanocrystal‐based photosensor integrated on low‐temperature polysilicon panels

Abstract— A photodetector using a silicon‐nanocrystal layer sandwiched between two electrodes is proposed and demonstrated on a glass substrate fabricated by low‐temperature poly‐silicon (LTPS) technology. Through post excimer‐laser annealing (ELA) of silicon‐rich oxide films, silicon nanocrystals formed between the bottom metal and top indium thin oxide (ITO) layers exhibit good uniformity, reliable optical response, and tunable absorption spectrum. Due to the quantum confinement effect leading to enhanced phonon‐assisted excitation, these silicon nanocrystals, less than 10 nm in diameter, promote electron‐hole‐pair generation in the photo‐sensing region as a result resembling a direct‐gap transition. The desired optical absorption spectrum can be obtained by determining the thickness and silicon concentration of the deposited silicon‐rich oxide films as well as the power of post laser annealing. In addition to obtaining a photosensitivity comparable to that of the p‐i‐n photodiode currently used in LTPS technology, the silicon‐nanocrystal‐based photosensor provides an effective backlight shielding by the bottom electrode made of molybdenum (Mo). Having a higher temperature tolerance for both the dark current and optical responsibility and maximizing the photosensing area in a pixel circuit by adopting a stack structure, this novel photosensor can be a promising candidate for realizing an optical touch function on a LTPS panel.     

Design of a low‐power‐consumption a‐IGZO TFT‐based Vcom driver circuit with long‐term reliability

Abstract— An amorphous‐InGaZnO (a‐IGZO) thin‐film transistor (TFT)‐based Vcom driver circuit that has long‐term reliability and can be integrated with the pixel array on a panel has been designed. Owing to the Vcom inversion, the power consumed by the proposed driving scheme is 40% less than that consumed by the conventional line‐inversion method. The high mobility (>10 cm²/V‐sec) of the a‐IGZO TFTs allows the integration of devices with small channel widths (<750 μm) and thus keeps the overall device size small, which is important for displays with narrow bezels. The lifetime of the Vcom driver is improved by AC driving (by clocking the n‐th and (n + 1)‐th frame with 20 and 0 V, respectively) of the buffer TFTs.     

Tuning space mapping with tuning exponent of T‐matrix

Tuning space mapping (TSM) with tuning exponent parameter of T‐matrix is proposed. A section of design interest in the electromagnetic (EM) model is replaced by “n” pieces cascaded T‐matrixes, and each T‐matrix is the EM‐simulated T‐parameter of preassigned unit cell circuit (PUCC). Finally the optimal exponent parameter of T‐matrix is transferred to original design variables. The proposed TSM not only inherits the advantages of circuit tuning element‐less (CTEL) TSM in prior art but also overcome the number range limitation that the tuning parameter must be positive for tuning in CTEL TSM. The proposed method has the minimal specification error and lowest simulation time comparing with other TSM methods. Verification examples, comparisons and discussions are also implemented. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:232–239, 2016.     

Robotic technologies for solar‐powered UAVs: Fully autonomous updraft‐aware aerial sensing for multiday search‐and‐rescue missions

Large‐scale aerial sensing missions can greatly benefit from the perpetual endurance capability provided by high‐performance low‐altitude solar‐powered unmanned aerial vehicles (UAVs). However, today these UAVs suffer from small payload capacity, low energetic margins, and high operational complexity. To tackle these problems, this paper presents four individual technical contributions and integrates them into an existing solar‐powered UAV system: First, a lightweight and power‐efficient day/night‐capable sensing system is discussed. Second, means to optimize the UAV platform to the specific payload and to thereby achieve sufficient energetic margins for day/night flight with payload are presented. Third, existing autonomous launch and landing functionality is extended for solar‐powered UAVs. Fourth, as a main contribution an extended Kalman filter (EKF)‐based autonomous thermal updraft tracking framework is developed. Its novelty is that it allows the end‐to‐end integration of the thermal‐induced roll moment into the estimation process. It is assessed against unscented Kalman filter and particle filter methods in simulation and implemented on the aircraft's low‐power autopilot. The complete system is verified during a 26 h search‐and‐rescue aerial sensing mock‐up mission that represents the first‐ever fully autonomous perpetual endurance flight of a small solar‐powered UAV with a day/night‐capable sensing payload. It also represents the first time that solar‐electric propulsion and autonomous thermal updraft tracking are combined in flight. In contrast to previous work that has focused on the energetic feasibility of perpetual flight, the individual technical contributions of this paper are considered core functionality to guarantee ease‐of‐use, effectivity, and reliability in future multiday aerial sensing operations with small solar‐powered UAVs.     

Wide‐locking range LC‐tank divide‐by‐4 injection‐locked frequency divider using transformer feedback

A wide locking range, injection locked frequency divider (ILFD) circuit topology is explored. The modulus‐four ILFD utilizes a cross‐coupled voltage‐controlled oscillator in conjunction with transformer feedback, parallel‐tuned resonator, and two‐segment, series mixers at the injection point. The transformer feedback and two‐segment mixing circuit topology achieves a locking range of 2.7 GHz (14.1 to 16.8 GHz) at an injection point bias of 0.9 Vdc and 0 dBm injection power. Spectral measurements at the ILFD output demonstrate proper phase‐lock operation and expected phase noise reduction using a high quality signal source at the ILFD input. The ILFD is implemented in the TSMC 0.18 μm 1P6M CMOS process, utilizes a die area of 0.839 × 0.566 mm² and consumes 16.56 mW. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:557–562, 2015.     

Vt Compensated voltage‐data a‐Si TFT AMOLED pixel circuits

Abstract— Active‐matrix organic light‐emitting‐diode (AMOLED) displays are now entering the marketplace. The use of a thin‐film‐transistor (TFT) active matrix allows OLED displays to be larger in size, higher in resolutions and lower in power dissipation than is possible using a conventional passive matrix. A number of TFT active‐matrix pixel circuits have been developed for luminance control, while correcting for initial and electrically stressed TFT parameter variations. Previous circuits and driving methods are reviewed. A new driving method is presented in which the threshold‐voltage (V_t) compensation performance, along with various circuit improvements for amorphous‐silicon (a‐Si) TFT pixel circuits using voltage data, are discussed. This new driving method along with various circuit improvements is demonstrated in a state‐of‐the‐art 20‐in. a‐Si TFT AMOLED HDTV.     

Dual‐wideband filtering power divider based on center‐fed three‐line coupled structure

In this article, a dual‐wideband filtering power divider is proposed by using a center‐fed three‐line coupled structure with three open stubs and two isolation resistors. The center‐fed three‐line coupled structure can generate two wide passbands separated by a transmission zero (TZ). The three open stubs can achieve four TZs around the two passbands, which is conducive to the frequency selectivity. Compared with the reported designs, the bandwidth is extended and the performance of isolation, insertion loss and circuit size can reach balance. The proposed design is implemented with size of 0.22 λ_g × 0.39 λ_g (λ_g is the guided wavelength at the center frequency of the lower passband) which exhibits the 3‐dB fractional bandwidths of 56.5%/24.27% and the insertion loss of 0.51/0.68 dB at the center frequency of two passband (f₁/ f₂) of 1.94/4.2 GHz, while the isolation at f₁/f₂ are higher than 22.5/20.1 dB.