Contribution of the fractal dimension to multiscale adaptive filtering of SAR imagery

Radar images can show great variability from pixel to pixel, which is an obstacle to effective processing. This variability, due to speckle created by the radar wave coherence, necessitates the use of more adapted filters. Previous studies have shown that multiresolution wavelet analysis yields better results but produces artefacts due to multiscale decomposition. This paper proposes a method that reduces these effects by introducing the fractal dimension. The resultant filter combines wavelet decomposition and variance change model based on the level of variance estimated by studying the fractal dimension of the image.     

A viable self-aligned bottom-gate MOS transistor technology for deep submicron 3-D SRAM

In this paper, the effect of the nonself-aligned process on the performance variation of a bottom-gate metal oxide semiconductor (MOS) transistor is discussed using a device simulator. The simulation results predict that the nonself-aligned bottom-gate MOS transistor cannot be scaled into the deep submicron regions. A simple fully self-aligned bottom-gate (FSABG) metal oxide semiconductor field effect transistor (MOSFET) technology is then proposed and developed. A new technique for forming thermal oxide on poly-Si serving as the bottom-gate dielectric is also investigated. It is found that the quality of the oxide on the poly-Si recrystallized by the metal induced uni-lateral crystallization (MIUC) is much higher than that by the solid phase crystallization (SPC). Deep submicron fully self-aligned bottom-gate pMOS transistors are fabricated successfully using the proposed technology. The experimentally measured results indicate the device performances depend strongly on the channel-width, and get comparable to that of a single crystal MOSFET if the channel width is less than 0.5/spl mu/m. The effects of the channel width on the device performances are discussed. In addition, the experimental results also confirm that the proposed technology has a good control of the channel film thickness.     

Millimetre wave performance of carbon-doped-base AlGaAs/GaAs HBTs

AlGaAs/GaAs HBTs with f/sub T/ of 52 GHz and f/sub max/ of 85 GHz have been obtained using a heavily-carbon-doped base layer. The HBT epitaxial layers were prepared by low-pressure MOVPE using carbon tetrachloride as the carbon source. To the author's knowledge, this work reports the first carbon-doped AlGaAs/GaAs HBTs with f/sub T/ and f/sub max/ greater than 50 GHz.<>     

Performance of adaptive token allocation in the leaky bucket

The leaky bucket is a popular method that can regulate traffic into an ATM broadband network. This paper examines a simple but innovative modification that would also provide priority to access the network. This is done by requiring cells of different classes to obtain different numbers of tokens before receiving their services. As a step further, a dynamic scheme can be used in which the tokens allocated to each class are changed according to the traffic load. Performance evaluations of mean cell delays and cell loss probabilities are obtained to provide insight into the behaviour of the system and to provide guideline for furture design.     

Low-power design techniques for high-performance CMOS adders

A high-performance adder is one of the most critical components of a processor which determines its throughput, as it is used in the ALU, the floating-point unit, and for address generation in case of cache or memory access. In this paper, low-power design techniques for various digital circuit families are studied for implementing high-performance adders, with the objective to optimize performance per watt or energy efficiency as well as silicon area efficiency. While the investigation is done using 100 MHz, 32 b carry lookahead (CLA) adders in a 0.6 μm CMOS technology, most techniques presented here can also be applied to other parallel adder algorithms such as carry-select adders (CSA) and other energy efficient CMOS circuits. Among the techniques presented here, the double pass-transistor logic (DPL) is found to be the most energy efficient while the single-rail domino and complementary pass-transistor logic (CPL) result in the best performance and the most area efficient adders, respectively. The impact of transistor threshold voltage scaling on energy efficiency is also examined when the supply voltage is scaled from 3.5 V down to 1.0 V     

Circularly polarized array antenna with corporate-feed network and series-feed elements

In this paper, corporate-feed circularly polarized microstrip array antennas are studied. The antenna element is a series-feed slot-coupled structure. Series feeding causes sequential rotation effect at the element level. Antenna elements are then used to form the subarray by applying sequential rotation to their feeding. Arrays having 4, 16, and 64 elements were made. The maximum achieved gains are 15.3, 21, and 25.4 dBic, respectively. All arrays have less than 15 dB return loss and 3 dB axial ratio from 10 to 13 GHz. The patterns are all quite symmetrical.     

Generalisation of inter-layer intra prediction for scalable video coding

In the scalable video coding (SVC) standard, a simple inter-layer intra prediction (ILIP) method has been adopted to reduce the bit rate of scalable video sequences. Proposed is an improved ILIP method by generalising the original one adopted in the SVC. Experimental results show that the proposed method can reduce bit rates by 4.1 to 5.9%, compared with the original one, while average PSNR is not decreased.     

Low temperature annealing behaviors of the titanium films formed by the ionized sputtering process on (001) silicon substrates

We investigated the low temperature reactions between the Ti films created by the ionized sputtering process and the (001) single crystal silicon wafers using high resolution transmission electron microscopy and x-ray diffractometry. We observed that the amorphous Ti-Si intermixed layer is formed at the Ti-Si interface whose thickness increased with the thickness of the deposited Ti films. The amorphous interlayer grew upon annealing treatments at the temperatures below 450°C. We also observed that the crystallization of the amorphous interlayer occurred upon annealing at 500°C. The first formed phase is Ti₅Si₃ in contact with Ti films, which is epitaxial with Ti films. Upon further annealing at 500°C, the Ti₅Si₄ phase and C49 TiSi₂ phase formed in the regions close to Ti films and Si substrates, respectively.     

Thermally controlled wavelength locker integrated in widely tunable SGDBR-LD module

A sampled-grating distributed Bragg reflector laser module having an integrated multiwavelength locker has been developed and evaluated. The uniquely designed wavelength locker made of thermally controlled etalon has provided uniform wavelength monitoring and very stable wavelength locking in the 188-ITU grid channels (37 nm) with 25-GHz spacing. Over the case temperature from -5/spl deg/C to 65/spl deg/C, the laser wavelength was locked within /spl plusmn/0.5 GHz, and the total power consumption of the module was less than 4 W.     

Modal analysis of radial-resonator waveguide diode mounts

A method of calculating the driving-point and transfer admittances of waveguide diode mounts with radial resonators is presented. The method is applicable to a variety of mount configurations, including the widely used resonant-cap mount. The analysis uses multimodal admittance matrices to represent the radial regions and their coupling and includes the influence of the waveguide boundary conditions. The analysis proceeds by first determining (from the matching of tangential fields at the common boundary) the coupling between radial regions in the form of a mode-coupling matrix. By multiplying this matrix with the generalized admittance matrices of connecting radial regions to form an overall admittance matrix, the driving-point and transfer admittances for a general radial-resonator mount can be extracted. The method is demonstrated by application to the resonant-cap mount. The accuracy of the analysis is confirmed by comparison with experimental results