This paper describes a meshless method with wavelet-based nodes for the two-dimensional time-dependent simulation of semiconductor devices. In this method the solution is approximated using global radial basis functions (RBF) and distributed wavelet-generated points. This allows the computation of problems with complex-shaped boundaries and forming fine and coarse points abundance in locations where variable solutions change rapidly and slowly, respectively. The method is suitable for the semiconductor part of very time consuming global modeling of microwave/millimeter wave circuits due to a large reduction of number of nodes with an acceptable results.
A radiant heat method was implemented to enhance the electron emission from the pyroelectric LiTaO3 crystal. An infrared (IR) lamp was utilized as a radiant heat source. The temperature gradient along the z-axis was smaller than 0.2°C/mm acquired for 20mm thick crystal. The highest electron emission current of 9.7nA is obtained by the temperature change of 150°C using a diameter of 20-mm and 20-mm thick LiTaO3 crystal. The total electron could be acquired as 1.27µC by integrating the emission-current curve for 20-mm thick crystals. It is 3.5 times higher than the electrons from the 10-mm long crystal.
Investigated here is a novel approach to the sidelobe suppression for noise synthetic aperture radar (SAR). The suggested strategy is a stable realization of apodization filtering (SRAF) with detailed implementation. Base on SRAF, a specific algorithm for noise SAR sidelobe suppression is proposed combining with range-Doppler (RD) algorithm. It applies SRAF to range correlation and azimuth compression to control sidelobes. The mathematic representations are presented and experimentation is performed. This algorithm proved that it can depress the sidelobes effectively and keep the energy of the mainlobe. Besides, it is not sensitive to noise disturbance and can avoid obvious SNR degradation.
For coding of quantized transform coefficients, a coded block pattern (CBP) is a key syntax element to represent the existence of coefficients in a macroblock efficiently. In H.264/AVC, the CBP is coded by using a fixed variable length coding table, called Exp-Golomb codes. However, since the CBP is highly affected by the change of quantization parameter (QP), in this paper, we show the CBP distributions according to the change of QP and propose an context-adaptive CBP coding method. The proposed scheme selects the coding table adaptively based on the context of neighbors' CBP. Experimental results show that the proposed scheme reduces average 1.15% in total bit rate and 12.54% in CBP bit rate compared to the anchor, H.264/AVC.
This paper presents a simple and optimized device layout developed by using diffusion rounding effect for better electrical behavior of transistors. TCAD analysis shows that diffusion rounding at the transistor source side can provide increased Ion with decreased Ioff because of the edge effect. The proposed diffusion-rounded CMOS shows as much as 10% improvement in the on-current (driving) and the off-current (leakage) is saved up to 10%. The inverter layout shows that proposed method requires less than a 4% cell area increase for the same driving strength of original cells.
In this paper, a dual-band bandpass filter with low insertion loss in the pass bands and compact size is designed using only two open-loop microstrip resonators loaded by in-line beelines. The in-line beelines, are loaded to achieve two passbands with high performance. By adjusting the stub lengths and widths and also the tap line position, the harmonics above the second band are supperssed. The minimum insertion loss is 0.9 and 0.2dB at the first and second passbands respectively. The minimum attenuation above the second passband is -19.5dB from 5.4 up to more than 20GHz, so it can be used for wideband applications. This filter is then fabricated and measured. The measured and simulated results are in good agreement.
It is presented that considering human bodies residing in a building is important for simulating indoor propagation. First, a simulation model of inhabited buildings was suggested. Next, electric field distribution obtained by numerical analysis and measurements were compared, so as to determine the reliability of the simulation results. Finally, the effects by the presence of people were examined by comparisons of the results obtained by using inhabited and uninhabited buildings. Simulation data corresponded very well with experimental data. The simulation results became remarkably realistic by taking into account people's distribution. Indeed, we conclude that considering residents can better describe a realistic propagation inside buildings.
In this letter, a new all digital phase locked loop (ADPLL) is proposed. The proposed ADPLL is introduced a new locking procedure with low complexity which results in an ultra low power design. The design uses only two up-down counters for finding the reference frequency. An efficient glitch removal filter and a new low power DCO are also introduced in this letter. The DCO achieves a reasonably high resolution of 1ps. The power consumption of the proposed ADPLL at 500MHz frequency is 820µW. The proposed ADPLL is simulated in 180nm CMOS with Hspice and verified by MATLAB.
The continuous scaling for fabrication technologies of electronic circuits demands the design of new and improved simulation techniques for integrated circuits. Therefore, this work shows a new double bounded polynomial homotopy based on a polynomial formulation with four solution lines separated by a fixed distance. The new homotopy scheme presents a bounding between the two internal solution lines and the symmetry axis, which allows to establish a stop criterion for the simulation in DC. Besides, the initial and final points on this new double bounded homotopy can be set arbitrarily. Finally, mathematical properties for the new homotopy are introduced and exemplified using a benchmark circuit.
In typical urban wireless channels with large delay spreads, the conventional TDoA (Time Difference of Arrival)-based mobile-WiMAX (Worldwide Interoperability for Microwave Access) positioning systems hardly satisfy the FCC (Federal Communications Commission)'s E-911 (Enhanced-911) detection criteria. In this paper, we propose a simple yet very effective TDoA-based position tracking algorithm for mobile-WiMAX systems when the user moves into GPS (Global Positioning System)-shadowed areas such as indoors or dense urban environments.
In this paper the implementation of hierarchical-modulated pilot signals for carrier frequency drift estimation in high mobility multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) system is introduced. Specifically for a hierarchical-modulated 64QAM-OFDM system in which three Layers with two bits in each Layer are defined from the constellation point and the carrier frequency drift estimation is facilitated from every Layer instead of using all six constellation bits to possibly simplify the design and reduce the time in the estimation process. The carrier frequency drift estimation by using only one Layer and the system performance at the receiver terminal by utilizing this Layer's estimated carrier frequency drift are simulated and compared for various high mobile speeds in Rayleigh fading channels.
A Kalman-based hypothesis testing (KHT) algorithm is proposed for mobile location estimation in non-line of sight (NLOS) environments. Hypothesis testing is employed to detect whether the environment is NLOS or LOS along with time of arrival (TOA) and received signal strength (RSS) measurements. And then an extended Kalman filter is used to nonlinear estimation. Simulation results show that the Kalman-based hypothesis testing algorithm has higher estimate accuracy in comparison with extended Kalman filter.
This paper describes an automatic level control (ALC) technique that utilizes cross gain modulation (XGM)-based wavelength conversion to expand the upstream transmission operating areas in optically-amplified passive optical network (PON) systems. We conduct experiments to evaluate the allowable link budgets of optically-amplified PON systems using XGM-based ALC (XGM-ALC), and also show that we can achieve a large operating area with a dynamic range in a trunk span of 18.5dB against an allowable link loss range for an access span of between 8.0 and 20.0dB. The allowable link loss range of an access span can be expanded to between 8.0 and 25.0dB if the dynamic range in the trunk span is reduced to 15.5dB. A total link budget of 55.0dB is achieved.
This paper proposes a test pattern generation and compression method to reduce test volume for VLSI testing. Unlike traditional approaches, the proposed scheme predefines linear relationships between vectors or within a vector of a test sequence firstly. Then, it determines test patterns by fault simulation. Therefore, patterns of a deterministic test set keep the predefined linear relationships, and can be highly compressed. Simulation results on ISCAS'89 benchmarks demonstrate that the proposed method can significantly reduce the data size with high fault coverage.
A scheme for efficient hardware implementation of central pattern generators (CPGs) on Field Programmable Gate Arrays (FPGAs) is proposed. A revised distributed-arithmetic (DA) algorithm is applied to the implementation to maximize the utilization of look up tables (LUTs) in FPGAs. The proposed scheme performances satisfactory experiment results which have correlation coefficients of 0.99 with simulation ones. In the mean time, it demonstrates 74% reduction in LUTs consumption, 75% in registers and 100% in embedded multipliers.