A miniature low‐power ultra‐wideband low noise amplifier in 0.18 μm CMOS

A 0.18‐μm CMOS low‐noise amplifier (LNA) operating over the entire ultra‐wideband (UWB) frequency range of 3.1–10.6 GHz, has been designed, fabricated, and tested. The UWB LNA achieves the measured power gain of 7.5 ± 2.5 dB, minimum input matching of ?8 dB, noise figure from 3.9 to 6.3 dB, and IIP3 from ?8 to ?1.9 dBm, while consuming only 9 mW over 3–10 GHz. It occupies only 0.55 × 0.4 mm² without RF and DC pads. The design uses only two on‐chip inductors, one of which is such small that could be replaced by a bonding wire. The gain, noise figure, and matching of the amplifier are also analyzed. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2011.     

Dual‐passband bandpass‐filtering power divider using half‐mode substrate integrated waveguide resonator with high frequency selectivity

In this paper, a half‐mode substrate integrated waveguide (HMSIW) power divider with bandpass response and good frequency selectivity is proposed. The proposed power divider includes input/output microstrip lines, four HMSIW resonators, cross‐coupling circuits, and an isolation resistor. The dual‐band bandpass‐filtering response is obtained by using the dual‐mode slotted HMSIW. To get good frequency selectivity, the input/output cross‐coupling circuits have been used, and several transmission zeros can be observed. A dual‐band filtering‐response HMSIW power divider is designed, fabricated and measured. The total size of the fabricated power divider is 0.58λg × 0.45λg. The measured results show a reasonable agreement with the simulated ones. The measured central operating frequencies of the dual‐band HMSIW power divider are at 2.43 and 3.50 GHz, respectively. The measured 3‐dB fractional bandwidth is about 13.3% and 6.3% in the two passbands, and the measured output isolation is about 20 dB.     

4032 ppi High‐resolution OLED microdisplay

A 0.5‐inch Ultra Extended Graphics Array (UXGA) organic light‐emitting diodes microdisplay has been developed with 6.3 μm pixel pitch. Not only 4032 ppi high resolution but high frame rate, low power consumption, wide viewing angle, and high luminance have been achieved. This newly developed organic light‐emitting diodes microdisplay is suitable for Near‐to‐Eye display applications, especially electronic viewfinders.     

Gain enhancement and mutual coupling reduction of multiple‐intput multiple‐output antenna for millimeter‐wave applications using two types of novel metamaterial structures

A method to significantly increase the gain and reduce the mutual coupling of microstrip multiple‐intput multiple‐output (MIMO) antenna based on metamaterial concept is presented. The μ‐negative and ε‐negative features of the proposed modified peace‐logo planar metamaterial (MPLPM) and two‐sided MPLPM (TSMPLPM) structures are calculated. The antenna structure consists of eight MPLPM slabs and two TSMPLPM, which are embedded in azimuth plane of a MIMO antenna vertically. The dimensions of MIMO antenna are 28 × 16 × 6.3 mm³ at 40 GHz. As a result, a compact MIMO antenna is simulated in comparison with primary microstrip structures. The corresponding return‐loss of the antenna is better than 10 dB over 34.5 to 45.5 GHz for Ka‐band applications. Good consent between the measured and simulated result is tacked. The maximum simulated gain of the structure is 15.5 dB at 40 GHz, creating a maximum gain improvement of 11.5 dB in comparison with a MIMO antenna without any metamaterial combinations. The value of the insertion‐loss (isolation) is 33 dB, which has improved by more than 25 dB compared to the conventional sample.     

Polarization‐independent modulation for projection displays using small‐period LC polarization gratings

Abstract— Progress in the use of liquid‐crystal polarization grating (LCPG) to modulate unpolarized (and polarized) light with a grating period as small as 6.3 μm is reported. Similar to LCPGs formed at larger periods (11 μm) reported previously, polarization‐independent switching, predominantly three diffraction orders, maximum contrast ratios of ～100:1 for unpolarized broadband light, very low scattering, and diffraction efficiencies >98% continue to be observed. The smaller period led to an expected lower threshold voltage, even though the thickness was greater. Because the smaller grating period enables a brighter result from a Schlieren projection scheme for a microdisplay using the LCPG light valve, the inherent tradeoffs involved with both material and design parameters are discussed, and prospects for a polarization‐independent projection display are commented upon.     

Experimental investigation and comparison of super‐wideband antipodal slot antennas

Three novel, super‐wideband antipodal slot antennas with different tuning stubs are studied and compared with each other. Smooth, half‐circular slot profile is used to improve the antennas' polarization purity and impedance bandwidth, and different tuning stubs are used to finely tune the antennas' radiation performance. As will be reported, low crosspolarization level, stable dipole‐like pattern, and flat gain performances can be obtained within an operation bandwidth of 6.3:1 by introducing a smooth antipodal slot structure and a cup‐shape tuning patch. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

A compact tri‐band microwave resonator for ethanol gas detection

This article presents the design, simulation, fabrication, and testing of a compact two‐port microwave resonator coated with nanomaterials for ethanol gas sensing applications. The proposed gas sensor consists of a transmission line loaded with three triangular split ring resonators for ethanol detection at three frequency bands viz. 2.2, 4.6, and 6.3 GHz. The transmission line has all‐pass characteristics in which band gaps are introduced using three split ring resonators. The TiO₂ and ZnO nanorods are used as sensitive layers for the proposed sensing application. The nanorods, which are grown on a glass substrate of thickness 1 mm, are loaded on to the two‐port microwave resonator making the device sensitive to ethanol. The microwave behavior of the sensor is analyzed using the scattering parameters. The absorption of the ethanol gas causes frequency detuning which is used to analyze the presence of ethanol and its concentration. From the experiments, it is understood that there is an increase in the frequency shift with an increase in the concentration of ethanol gas. The sensing device with ZnO as a sensitive layer showed a higher average sensitivity of 2.35 compared to TiO₂ whose average sensitivity is 1.29.     

Frequency‐dependent behavioral‐model‐based nonlinear analysis and design of a low‐profile transmit active phased array antenna

Design and behavioral‐model‐based nonlinear analysis of a 3‐GHz active‐phased array antenna (APAA) are presented. Four nonlinear power amplifiers are employed in the output ports of the feeding network (FN) and analyzed based on a 5‐order polynomial model with frequency‐dependent coefficients. The FN is based on 4‐port new Gysel power dividers and combiners arranged in such a way to feed the array with Gaussian‐like amplitude and in‐phase distributions. Beam steering capability is obtained in 2 directions by a new technique including a phase shifter and an amplitude controller (AC). The features result in a low‐profile APAA whose design and fabrication complexity and cost are reduced. Single and 2‐tone power tests are performed to develop analytical expressions in nonlinear region for array factor as a function of the model, FN and the phase and ACs. A similar system with frequency‐independent model is also analyzed for comparison in terms of scan loss, beamwidth, side‐lobe level, beam position, and gain. A microstrip array antenna including the power amplifiers, pre‐amplifiers, AC, delay‐line‐based phase shifters and Gysels is fabricated and measured. The simulation results at the single and dual tones and the intermodulation products are presented which have a good agreement with the measurements.     

Asymmetric tri‐band linear‐to‐circular polarization converter in transmission mode

In this article, we propose a metasurface which has function as tri‐band linear‐to‐circular transparent polarization converter based on combining multiple plasmon resonances and Fabry‐Perot‐like resonances. The metasurface is composed of three layers of metallic pattern arrays separated by two‐layer dielectric. The proposed metamaterial can convert incident linearly polarized waves into circularly polarized waves in three frequency bands, and the transmission efficiency reaches up to 90%. When x‐polarized forward wave is normally incident, the transmitted right‐handed circular polarized spectra with axial ratio less than 3 dB are in the range of 18.7 to 21.5 and 46.1 to 50.3 GHz; the left‐handed circular polarized spectrum is 28.7 to 34.3 GHz. The physical mechanism of the polarization converter is analyzed in detail, and an experiment is carried out to verify the proposed polarization converter.     

Hepta‐band coupled‐fed antenna for metal‐ring‐frame WWAN/LTE smartphone applications

A small‐size 40 mm × 10 mm coupled‐fed antenna for hepta‐band WWAN/LTE metal‐ring‐frame (MRF) smartphone applications is investigated. Unlike conventional solutions that remove the redundant resonances excited by the MRF, the proposed antenna makes full use of the MRF resonances. By meticulously co‐design the antenna and MRF, multi‐resonance frequencies are excited and integrated, which results in achieving hepta‐band operation for an MRF smartphone antenna. Detail design considerations and experimental results of the proposed antenna are provided and analyzed. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:633–639, 2016.     

Novel offset‐fed dual‐band aperture‐dipole composite antenna: Operating principle and design approach

Operating principle and design approach of a novel dual‐band aperture‐dipole composite antenna are proposed. It is shown that multiple operating modes can be simultaneously excited by employing offset‐feeding technique at first. After the behavior of each mode is studied, the operating principle of the antenna is analyzed and described. Then, an improved dual‐band aperture‐dipole composite antenna is formed and it is designed by using the proposed approach. The antenna is experimentally verified. It is demonstrated that two operating bands for radiation are ranged from 2.36 to 2.58 GHz and from 4.1 to 15.72 GHz, respectively, in which the reflection coefficient are both 相似文献   

Self‐calibration three‐dimensional light field display based on scalable multi‐LCDs

Approach to achieve self‐calibration three‐dimensional (3D) light field display is investigated in this paper. The proposed 3D light field display is constructed up on spliced multi‐LCDs, lens and diaphragm arrays, and directional diffuser. The light field imaging principle, hardware configuration, diffuser characteristic, and image reconstruction simulation are described and analyzed, respectively. Besides the light field imaging, a self‐calibration method is proposed to improve the imaging performance. An image sensor is deployed to capture calibration patterns projected onto and then reflected by the polymer dispersed liquid crystal film, which is attached to and shaped the diffuser. These calibration components are assembled with the display unit and can be switched between display mode and calibration mode. In the calibration mode, the imperfect imaging relations of optical components are captured and calibrated automatically. We demonstrate our design by implementing the prototype of proposed 3D light field display by using modified off‐the‐shelf products. The proposed approach successfully meets the requirement of real application on scalable configuration, fast calibration, large viewing angular range, and smooth motion parallax.     

A nonlinear state‐feedback state‐feedforward tracking control strategy for a boiler‐turbine unit

A boiler‐turbine unit is a primary module for coal‐fired power plants, and an effective automatic control system is needed for the boiler‐turbine unit to track the load changes with the drum water level kept within an acceptable range. The aim of this paper is to develop a nonlinear tracking controller for the Bell‐Åström boiler‐turbine unit. A Takagi‐Sugeno fuzzy control system is introduced for the nonlinear modeling of the Bell‐Åström boiler‐turbine unit. Based on the Takagi‐Sugeno fuzzy models, a nonlinear tracking controller is developed, and the proposed control law is comprised of a state‐feedforward term and a state‐feedback term. The stability of the closed‐loop control system is analyzed on the basis of Lyapunov stability theory via the linear matrix inequality approach and Schur complement. Moreover, model uncertainties are also considered, and it is proved that with the proposed control law the tracking error converges to zero. To assess the performance of the proposed nonlinear state‐feedback state‐feedforward control strategy, a nonlinear model predictive control strategy and a linear strategy are presented as comparisons. The effectiveness and the advantages of the proposed nonlinear state‐feedback state‐feedforward control strategy are demonstrated by simulations.     

Coplanar‐to‐rectangular waveguide millimeter‐wave transitions manufacturing tolerance analysis using the finite‐element method

A 94.5‐GHz coplanar to rectangular transition for satellite telecommunications is analyzed via the finite‐element method (FEM). Particular attention is devoted to the effects of manufacturing tolerances, and a full statistical behavior, extracting the effects of single geometrical details, is presented. Obtained data are validated by the measurements of the prototypes. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

Compact sub‐6 GHz 5G‐multiple‐input‐multiple‐output antenna system with enhanced isolation

A compact two‐element multiple‐input‐multiple‐output (MIMO) antenna system with improved impedance matching and isolation is presented for future sub‐6 GHz 5G applications. The two identical tapered microstrip line fed modified rhombus‐shaped radiating elements are placed in the same orientation at a compact substrate area of 0.24λ₀ × 0.42λ₀ (where, λ₀ at 3.6 GHz) on a shared rectangular ground. A remodeled T‐shaped ground stub is placed between a pair of radiating element to achieve improved impedance bandwidth and isolation. Further, a split U‐shaped stub connected to center of each radiating element to achieve the desired resonant frequency of 3.6 GHz. The proposed antenna covers a ?10 dB operating band of 3.34 to 3.87 GHz (530 MHz) with more than 20 dB isolation between a pair of elements. MIMO performances are also analyzed and experimentally validated. The measured performances of a prototype are found in good agreement with simulated performances. Further, the simulation study is carried out to see the effect of housing and extended ground plane on two‐element MIMO antenna for practical application. An idea of realization of 12‐element MIMO is also studied using the proposed two‐element MIMO antenna.     

Programmable‐logical‐controllers Synthesis for Automated‐guided‐vehicle Systems Using Ordinary Petri Nets

An ordinary Petri‐net (PN) based approach is proposed to design the programmable logical controller (PLC) for preventing collisions between vehicles in an automated guided vehicles (AGV) system. First, method is proposed to model an AGV system as an ordinary PN, called the plant PN. Second, for collision prevention in an AGV system, module control methods are proposed to design the PN supervisor (the closed‐loop PN) by augmenting the plant PN. In detail, three modules are defined the line, divide, and merge modules, in the plant PN, and the control module methods are presented for each of these three modules. As a result, the closed‐loop PN of an AGV system is obtained and can be analyzed using the PN theory. Finally, method is proposed to translate a closed‐loop PN into a ladder diagram. Consequently, the PN supervisor is implemented by a PLC using these proposed methods. A laboratory AGV system is used to illustrate this approach.     

Prospects of emerging polymer‐stabilized blue‐phase liquid‐crystal displays

Abstract— The prospects of emerging polymer‐stabilized blue‐phase liquid‐crystal displays, or more generally, Kerr‐effect‐induced isotropic‐to‐anisotropic transition, are analyzed with special emphases on the temperature effects. As the temperature increases, both the Kerr constant, induced birefringence, and response time decrease but at different rates. The proposed physical models fit well with experimental results. Some remaining technical challenges associated with this promising display technology are discussed.     

Polymer‐stabilized pretilt angle on the surface of nanoparticle‐induced vertical‐alignment surface for multi‐domain vertical‐alignment liquid‐crystal display

Abstract— By introducing polyhedral oligomeric silsesquioxane (POSS) nanoparticles along with a controlled amount of UV‐curable reactive mesogen (RM) into a liquid‐crystalline (LC) medium, a multi‐domain vertical‐alignment LC device was successfully demonstrated. The device, possessing a vertically aligned LC director in four different azimuthal directions, exhibited a fast response time and wide‐viewing‐angle characteristics, in the absence of conventional polymer‐type vertical‐alignment layers. Electro‐optic characteristics of the fabricated device, before and after UV curing of the cell, were studied. The surface morphology of the substrate surfaces were analyzed by using field‐emission scanning electron microscopy (FESEM). The experimental results show that the technology will possibly be applicable to cost‐effective vertical‐alignment liquid‐crystal devices and is suitable for green‐technology liquid‐crystal displays.     

Moving‐image simulation for high‐quality LCD TVs

Abstract— A simulation system incorporating pixel response and eye‐trace integration was developed to evaluate the moving‐image performance of high‐quality LCD TVs. A simple formula was derived for moving‐edge simulation, which can be used to evaluate the visual effects of arbitrary response waveforms. A model of exponential decay with dynamic time constants is proposed for the LC response to perform moving‐image simulation. The model was used to evaluate the visual effects of various motion‐blur‐reduction techniques. Six different motion‐blur‐reduction techniques were evaluated in terms of their visual effects. Among them, three basic techniques show certain defects, which are further analyzed by simulation. The other three advanced techniques show excellent performance, and, therefore, are recommended for use in high‐quality LCD TVs.     

Input‐to‐output stabilization of nonlinear systems via backstepping

An extension of backstepping method for stabilization of nonlinear systems with respect to a set is presented. Robust control laws providing the system with input‐to‐output stability are proposed. Possibilities of non‐strict Lyapunov functions' application are discussed. The differences between a conventional backstepping method and an approach proposed in Kolesnikov (Synergetic Control Theory. Energoatomizdat: Moscow, 1994; 344) are analyzed. Performance of the obtained solutions is demonstrated by computer simulation for pendulum with actuator example. Copyright © 2008 John Wiley & Sons, Ltd.