Application of the hybrid Hopkins–Abbe method in full-chip OPC

The hybrid Hopkins–Abbe method is presented and shown to resolve the problem of the traditional Hopkins theory, namely the requirement for constant mask diffraction efficiencies. Simulation of electromagnetic scattering from the mask that takes into account the oblique angles of incidence from the illumination is performed by application of the domain decomposition method that is extended for offaxis illumination. Examples of 45 nm and 32 nm lines and spaces through pitch and through focus are presented to demonstrate the validity and accuracy of the hybrid Hopkins–Abbe method. The results obtained are in excellent agreement with a rigorous and independent (third party) simulator.     

Application of the inner–outer flexible GMRES-FFT method to the analysis of scattering and radiation by cavity-backed patch antennas and arrays

The finite element-boundary integral (FE-BI) method is applied for the analysis of scattering and radiation by cavity-backed patch antenna and arrays. In this investigation, the FE-BI formulations have been implemented using brick element volumes and it allows for a particular use of the efficient FFT-based iterative solver. The inner–outer flexible GMRES algorithm is applied to solve the equation with a higher convergence speed when compared with the standard GMRES algorithm.     

Information-theoretic analysis of efficiency of the phonetic encoding–decoding method in automatic speech recognition

A words phonetic decoding method in automatic speech recognition is considered. The properties of Kullback–Leibler divergence are used to synthesize the estimation of the distribution of divergence between minimum speech units (e.g., single phonemes) inside a single class. It is demonstrated that the minimum variance of the intraphonemic divergence is reached when the phonetic database is tuned to the voice of a single speaker. The estimations are proven by experimental results on the recognition of vowel sounds and isolated words of Russian language.     

The design of a mode selective directional coupler for a high power gyroklystron†

The design method of mode selective directional couplers from a transverse electric mode in a circular waveguide to the fundamental mode in a rectangular wave guide is presented in this paper. The design results for a TE₀₁ circular mode coupler intended for use in the output power measurement of a high power gyroklystron are reported; these results indicate that more than 50-80dB directivity and sufficient suppression of unwanted modes can be obtained with a coupler less than 07m in length. The effects of frequency and rectangular wave guide size on coupler parameters are also discussed in this paper     

Application of a Hybrid Taguchi-Genetic Algorithm to the Multiobjective Design Optimization of Yagi–Uda Antennas

In this paper, a hybrid Taguchi-genetic algorithm (HTGA) is used to optimize Yagi–Uda antennas. The method combines the traditional genetic algorithm, known to have a powerful global exploration capability, with the Taguchi method, which can exploit the optimum offspring and consequently, enhance the genetic algorithm. The aim is to devise antenna geometrical parameters that allow the antenna to simultaneously improve multiple performances such as gain, sidelobe level, and input impedance. Thus, not only will a new antenna configuration be found, but the demonstration of the ability of the HTGA method to design antenna structures with more than one goal is investigated as well.     

Preconditioned method for the nonlinear complex Ginzburg–Landau equations

Wireless Networks - In this work, we give an effective preconditioned numerical method to solve the discretized linear system, which is obtained from the space fractional complex...     

Experimental determination of the derivative of the current–voltage characteristic of a nonlinear semiconductor structure using modulation Fourier analysis

The derivative of the nonlinear current–voltage characteristic of two antiparallel p–n junctions is experimentally obtained by the method of modulation Fourier analysis. The derivative of the current–voltage characteristic is reconstructed using the current dependences of the first and higher voltage harmonics. The advantage of modulation Fourier analysis over numerical differentiation is experimentally validated for the first time. The applied technique has no limitations on the current modulation amplitude. Large amplitudes make it possible to identify the nature of the nonlinearity of the dependence under study and to determine the contribution of the nonlinear fraction against the background of significant linearity.     

An improved method for the design of quadrature mirror filter banks using the Levenberg–Marquardt optimization

This paper presents an improved and efficient method for the design of a two-channel quadrature mirror filter (QMF) bank. In the proposed method, the filter bank design problem is formulated as a low-pass prototype filter design problem, whose responses in the passband and stopband are ideal and their filter coefficients value at quadrature frequency is 0.707. A new method is developed for the design of a low-pass prototype filter which minimizes the objective function by optimizing the filter taps weights using the Levenberg–Marquardt method. When compared with other existing algorithms, it significantly reduces peak reconstruction error (PRE), error in passband, stopband and transition band. Several design examples are included to show the increased efficiency and the flexibility of the proposed method over existing methods. An application of this method is considered in the area of subband coding of the ultrasound images.     

A method for the amplitude–phase synthesis of antenna array based on control of the set of nonidentical partial beams

An iterative method for the amplitude–phase synthesis of antenna arrays based on control of the set of partial beams is proposed. In this method, two additional partial beams are added to the radiation pattern at each step. The shape of each beam is optimized with consideration for the difference between the synthesized and specified radiation patterns. Parameters specifying the shape of additional partial beams are chosen with the help of the genetic algorithm. The results of numerical studies allowing comparison of the proposed synthesis method to the least-squares method and the method based on control of the set of identical partial beams are presented.     

Effect of the anode-emitter injection efficiency on the characteristics of hybrid SIT–MOS transistors

The possibility of optimizing high-voltage hybrid SIT–MOP transistors (HSMTs) by means of a local reduction in lifetime near the anode emitter and/ or by decreasing its injection efficiency by three different methods is studied using two-dimensional numerical simulation. It is shown that all four optimization methods are equivalent from the physical point of view and make it possible to decrease the turn-off energy loss E_off by 30–40%, as in insulated gate bipolar transistors (IGBTs). However, all other conditions being equal, the energy E_off in the HSMT appeared 15–35% lower than in equivalent trench IGBTs.     

Design and experimental analysis of fiber grating vibration demodulation system based on the 3 × 3 coupler

A novel fiber grating vibration demodulation system, based on 2×2 and 3×3 couplers, is designed. Based on the phase unwrapping algorithm, the three-way asymmetrical output of the 3×3 coupler and demodulation state characteristics of the system when the vibration signal includes high harmonic waves are analyzed in simulations. The result shows that when the three-way output is asymmetrical, the maximum deviation of demodulation signal is 1.625%, and when the vibration signal includes high harmonic waves, the maximum deviation of demodulation signal is 0.9%. The corresponding experiment is conducted. The experimental result shows that the dynamic resolution of the system is 25.22 nɛ / $ \sqrt {Hz} $ \sqrt {Hz} when the vibration pitch is 5.5 Hz.     

On the Fabrication of Graphene p–n Junctions and Their Application for Detecting Terahertz Radiation

Semiconductors - A new method for the formation of lateral p–n junctions in epitaxial graphene with the use of UV (ultraviolet) radiation is considered. The UV illumination method makes it...     

An Algorithm for the Design of a Cost-Optimized Topology for the Fixed Part of a GSM Network

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A simple method for determination of Fowler–Nordheim tunnelling parameters

A simple technique for extracting the Fowler–Nordheim (FN) tunnelling parameters is proposed. It consists of measuring the Drain-Source current of a floating gate transistor while a linear ramp voltage is applied to a simple injector structure attached to the transistor's floating gate. Such a test device is fabricated using a standard CMOS process. The parameters obtained can be used in a freely available electrical simulator as SPICE3f5 (NGSPICE), but in general it can be easily adapted to other SPICE-like programs. We describe the technique step-by-step and a comparison is made of simulated and measured FN tunnelling parameters, for a floating gate transistor with tunnelling injectors. A good agreement has been found between experimental and simulated data.     

A numerical–analytical method for calculation of curved dipole antennas

A numerical–analytical method for solution of equations and calculation of the input impedance of thin dipole antennas of arbitrary shape has been developed. High efficiency of the method has been demonstrated by examples.     

Thermal analysis and design of a 75-W hybrid-type DC–DC converter for space applications

Hybrid DC–DC converters for space applications should be designed for operation at full rated power within the military specification for temperature range of −55 to +125 °C. Hence, the thermal design is a crucial step in the design process of converter, ensuring that no component of the converter exceeds its rated maximum operating temperature. One of the objectives of this work is to guarantee that all electronic components operate below their maximum allowable temperature. For this purpose, a three dimensional model of a converter based on the finite element method was developed. Results based on numerical simulation were validated by experimental data from infrared camera. The total amount of dissipated power in every component was determined experimentally based on a prototype converter. In the case of a component with high power consumption, such as the field effect transistor, the increase in temperature was minimized by applying designed heat sink with a high-thermal-conductivity material.     

Development of a Method for Chemical–Mechanical Preparation of the Surface of CdZnTe Substrates for HgCdTe-Based Infrared Focal-Plane Arrays

This paper reports the first implementation in our laboratory of a chemical–mechanical polishing (CMP) process for CdZnTe (CZT) substrates prepared for growth of HgCdTe layers by liquid phase epitaxy and molecular beam epitaxy. The process enables significant reduction of the thickness of the damaged zone induced by the mechanical polishing that must be etched away before epitaxy. Resulting improvements in surface morphology, in terms of waviness and density of point defects, are reported. The chemical state of surfaces polished by CMP was characterized by x-ray photoelectron spectroscopy. The chemical state was highly homogeneous; comparison with a reference surface is reported. End use assessment of this surface processing was compared with that of reference substrates by preparation of focal-plane arrays in the medium-wavelength infrared spectral range, by using epitaxial layers grown on substrates polished by different methods. The electro-optical performance of the detectors, in terms of photovoltaic noise operability, are reported. The results reveal that the state of this CMP surface is at the level of the best commercial substrates.     

Steady-state analysis of the carrier synchronizer for QPSK signals†

In this paper, the steady-state analysis of the carrier synchronizer consisting of the cascade of a bandpass filter (BPF), and non-linearity (NL) and a phase-locked loop (PLL) for a quadrature phase shift keyed (QPSK) signal corrupted by white gaussian noise is presented. The analysis is based on the transform method and the harmonic representation of cyclostationary processes. Some of the conclusions are similar to those obtained from the non-return to zero (NRZ) pulse amplitude modulated (PAM) synchronizer. Among these include: (1) the odd symmetry NL cannot be adopted to restore the carrier; (2) there is an optimum bandwidth of the BPF to minimize the phase jitter of the synchronizer output signal; and (3) conventional design theory still applies for the PLL in the QPSK carrier synchronizer. In addition to these results, we also conclude that: (1) we have to choose a harmonic with order of at least 4; and (2) the PLL output phase variance is more sensitive to the synchronizer input signal-to-noise ratio (S/N) than the NRZ synchronizer. A significant improvement of the QPSK synchronizer performance over that of the NRZ case is possible when the S/N is large.