Applied Mechanics and Materials Vols. 764-765

Abstract: With the development of the Internet, how to provide a high-speed and high-security comprehensive network has become urgent issue. In this project, we propose hybrid analog/digital transmissions format scheme which integrated optical code-division multiple-access (OCDMA) and polarization multiplexing technique in free space optics (FSO) transmission. Orthogonal frequency division multiplexing (OFDM) transmits as the analog format and (on-off keying) OOK transmits as digital format in the study, respectively. In the proposed hybrid OCDMA system, it has high-speed transmission, signal security and low cost...etc. we adopt quasi-orthogonal Walsh-Hadamard codes (WHC) that with fixed cross correlation value as the codeword for each base station. With the property, the multiple access interference (MAI) can be efficiently eliminated by using the balanced detection scheme at the receive end. The constellation and eye diagrams show that both OFDM signal as analog signal and OOK modulation as digital signal in the proposed hybrid OCDMA system perform good performance in FSO transmission.

Abstract: The objective of this paper is to evaluate the impact of the parasitic capacitor to the Gallium-Nitride (GaN) based high-electron-mobility transistor (HEMT). Because of the high switching frequency operation, the parasitic inductor has caught a lot of attention when the GaN HEMT is applied in the high power applications. However, the impact of parasitic capacitor to the GaN HEMT is not discussed in literatures. A prototype circuit is built and tested to evaluate the impacts of parasitic capacitor to the GaN HEMT performance. The results show that the parasitic capacitor can induce voltage spike and damage the GaN HEMT.

Abstract: This paper presents how to improve specific o n-state resistance (Ron) induced by the HCI of a SOI LDMOS device. In manufacturing of UHV device, trade-off between on state resistance and breakdown voltage is always present. But with our process design we are able to improve Ron degradation without compromising the-breakdown voltage. In our design the peak electric field is under gate near source side, due to low electric field near drain helps to increase the current flow much better hence it helps to improve Ron and Vth. If the peak field is located near drain side, the hot holes is easy to penetrate to field oxide and avoid current flow then it causes increase in the Ron.Our simulation results shows 0.27% and 0.95% Ron and Vth increases respectively even at 1e5 second stress time .The Ron degradation phenomenon was analyzed with the 2-D simulation of electric field and impact ionization generation.

Abstract: For IC component designs, ESD is one of an important issue which has to be taken in consideration for reliability of a device. We use the TLP Voltage Stepping simulation scheme in Medici simulation for 5V NMOS Multi-finger structure, the use of silicon model and set of variables, in silicon material parameter is used to vary the variable electron and hole parameters of silicon, which can make the Holding Voltage simulation change and to make the simulation and the silicon data more consistent. We have simulated and calibrated Holding voltage of 5V NMOS multi finger to match with silicon data.

Abstract: Ion implantation and subsequent diffusion are very essential stages in today's advanced VLSI (Very Large Scale Integration) semiconductor devices processing. High precision calibration of device simulation is a key procedure to ensure simulation is accurate. For this purpose, accurate prediction of the doping profiles resulted from ion implantation and diffusion will be studied using a few models of ion implantation and diffusion. We collected data of Boron as P-type ion implantation profiles using TCAD simulation software with different ion implantation models and diffusion models then compared with Secondary Ion Mass Spectrometry (SIMS) data of ion implantation profile database as experimental data. Models plays very important role in this calibration. In this paper, calibrations have done using Monte Carlo and Taurus analytical as implantation model and pd.full, pd.fermi and pd.5stream as diffusion model. All calibration simulations were simulated using Synopsys TCAD Simulation. The experimental results shown by using Monte Carlo ion implantation model with pd.5str diffusion model is close to SIMS profile.

Abstract: In this paper, we propose an unambiguous signal tracking scheme for composite binary offset carrier (CBOC) signal tracking. First, we obtain partitioned sub-carriers and partial correlations. Based on a recombination of the partial correlations, we propose a novel correlation function without side-peaks. From numerical results, the proposed correlation function is found to offer a better tracking performance than that of the conventional correlation function in terms of the tracking error standard deviation.

Abstract: While the LLC regulator configuration presents advantages such as resonant soft switching and transformer built-in resonant elements, it does have the disadvantage of poor light-load efficiency due to higher switching frequency operation under such a condition. Using the GaN-Si FET cascode switches significantly improves the situation. Experimental results are also presented.

Abstract: This paper proposes a method using non-linear voltage-current characteristics for multiple harmonic sources classification using wavelet hybrid neural network (WHNN). Typical voltage-current characteristics of harmonic sources are non-linear closed curves in the time-domain, referring to the converters, reactors, and non-linear loads. The hybrid neural network is a two-subnetwork architecture, consisting of wavelet layer and a self-organizing feature map (SOFM) network connected in cascade. The effectiveness of the proposed method is demonstrated by numerical tests. The results of multiple harmonic sources show the computational efficiency and accurate classification.

Abstract: Robust and accurate positioning systems with seamless outdoor and indoor coverage have been receiving a great deal of attention. In outdoor environments, as radio signals transmitted from base stations or satellites are jammed or shielded, to estimate an accurate location using only the absolute positioning scheme remains a difficult problem regarding location accuracy. In order to overcome the drawback of the ranging scheme based on the radio signals, this paper presents a positioning approach based on inertial-measurement-unit (IMU) observations to estimate the location of a mobile terminal (MT). For the location-estimation technique, the positioning experiment is handled by the dead-reckoning (DR) algorithm. By processing the observations from the IMU, it is possible to estimate the movement of an MT (car). In terms of the IMU-based approach, although the experimental results demonstrate that the positioning scheme using the DR algorithm causes the error propagation, the approach can work in short period of time for navigation applications.

Abstract: The least squares (LS) approach has been widely used for solving the GPS navigation solution. Despite its many superior properties, however, the LS estimate can be sensitive to outliers and its performance in terms of accuracy and statistical inferences may be compromised when the errors are large and heterogeneous. The GPS signal is strongly affected by the multipath propagation errors. The LS is not able to cope with the above condition to provide a useful and plausible solution. In this paper, an alternative approach based on the least absolute deviation (LAD) criterion for estimating the navigation solution is carried out. The LAD method, which is also known as the L1 method, provides a useful and plausible solution. Unlike the LS method, the LAD method is not as sensitive to the outliers and so as to provide more robust estimates. Simulation results show that the method can effectively mitigate the GPS multipath errors.