This paper presents a standard cell-based frequency synthesizer with dynamic frequency counting (DFC) for multiplying input reference frequency by N times. The dynamic frequency counting loop uses variable time period to estimate and tune the frequency of digitally-controlled oscillator (DCO) which enhances frequency detection's resolution and loop stability. Two ripple counters serve as frequency estimator. Conventional phase-frequency detector (PFD) thus is replaced with a digital arithmetic comparator to yield a divider-free circuit structure. Additionally, a 15 bits DCO with the least significant bit (LSB) resolution 1.55 ps is designed by using the gate capacitance difference of 2-input NOR gate in fine-tuning stage. A modified incremental data weighted averaging (IDWA) circuit is also designed to achieve improved linearity of DCO by dynamic element matching (DEM) skill. Based on the proposed standard cell-based frequency synthesizer, a test chip is designed and verified on 0.35-µm complementary metal oxide silicon (CMOS) process, and has a frequency range of (18-214) MHz at 3.3 V with peak-to-peak (Pk-Pk) jitter of less than 70 ps at 192 MHz/3.3 V.

This paper presents the design of a novel method for improvement of the operation of distance relays during capacitive voltage transformer transients using artificial neural network. The proposed module uses voltage and current signals to learn the hidden relationship existing in the input patterns. Simulation studies are preformed and the influence of changing system parameters, such as fault resistance and source impedance is studied. Details of the design procedure and the results of performance studies with the proposed relay are given in the paper. Performance studies results show that the proposed algorithm decreases the effects of CVT transients and is fast and accurate.

The problems with the CV characterization on very leaky (thin) nitrided oxide are mainly due to the measurement precision and MOS gate dielectric model accuracy. By doing S-parameter measurement at RF frequency and using simple but reasonably accurate model, we can obtain proper CV curves for very thin nitrided gate dielectrics. Regarding the measurement frequency we propose a systematic method to find a frequency range in which we can select measurement frequencies for all biases to obtain a full CV curve. Moreover, we formulated the first order relationship between the measurement frequency range and the test structure design for CV characterization. With the established formulae, we redesigned the test structures and verified that the formulae can be used as a guideline for the test structure design for RFCV measurements.

This paper describes a dynamic and adaptive scheme for three-dimensional mesh morphing. Using several control maps, the connectivity of intermediate meshes is dynamically changing and the mesh vertices are adaptively modified. The 2D control maps in parametric space that include curvature map, area deformation map and distance map, are used to schedule the inserting and deleting vertices in each frame. Then, the positions of vertices are adaptively moved to better positions using weighted centroidal voronoi diagram (WCVD) and a Delaunay triangulation is finally used to determine the connectivity of mesh. In contrast to most previous work, the intermediate mesh connectivity gradually changes and is much less complicated. We demonstrate several examples of aesthetically pleasing morphs created by the proposed method.

The role of hydrogen in the Si film during excimer laser annealing (ELA) has been successfully studied by using a novel sample structure, which is stacked by a-Si film and SiN film. Hydrogen contents in the Si films during ELA are changed by preparing samples with hydrogen content of 2.3-8.2 at.% in the SiN films with a use of catalytic (Cat)-CVD method. For the low concentration of hydrogens in the Si film, the grain size increases by decreasing hydrogen concentration in the Si film, and the internal stress of the film decreases as increasing the shot number. For the high concentration of hydrogens in the Si film, hydrogen burst was observed at 500 mJ/cm2 and the dependence of the internal stress on the shot number becomes weak even at 318 mJ/cm2. These phenomena can be understood basically using the secondary grain growth mechanism, which we have proposed.

In this paper, a novel digitally-controlled varactor (DCV) for portable delay cell design is presented. The proposed varactor uses the gate capacitance differences of NAND/NOR gates under different digital control inputs to build up a digitally-controlled varactor. Then the proposed varactor is applied to design a high resolution delay cell and to achieve a fine delay resolution. Different types of NAND/NOR gates (2-input or 3-input) for DCV design are also investigated in this paper. The proposed DCV can be implemented with standard cells, thus it can be easily ported to different processes in a short time. A test chip fabricated on a standard 0.35 µm CMOS 2P4M process proves that the proposed delay cell has a fine delay resolution about 1.55 ps. As a result, the proposed DCV exhibits finer resolution, better linearity, and better portability than traditional delay elements, and is very suitable for portable delay cell design.

This paper presents some effective methods for improving the performance of a speaker identification system. Based on the multiresolution property of the wavelet transform, the input speech signal is decomposed into various frequency subbands in order not to spread noise distortions over the entire feature space. For capturing the characteristics of the vocal tract, the linear predictive cepstral coefficients (LPCC) of the lower frequency subband for each decomposition process are calculated. In addition, a hard threshold technique for the lower frequency subband in each decomposition process is also applied to eliminate the effect of noise interference. Furthermore, cepstral domain feature vector normalization is applied to all computed features in order to provide similar parameter statistics in all acoustic environments. In order to effectively utilize all these multiband speech features, we propose a modified vector quantization as the identifier. This model uses the multilayer concept to eliminate the interference among the multiband speech features and then uses the principal component analysis (PCA) method to evaluate the codebooks for capturing a more detailed distribution of the speaker's phoneme characteristics. The proposed method is evaluated using the KING speech database for text-independent speaker identification. Experimental results show that the recognition performance of the proposed method is better than those of the vector quantization (VQ) and the Gaussian mixture model (GMM) using full-band LPCC and mel-frequency cepstral coefficients (MFCC) features in both clean and noisy environments. Also, a satisfactory performance can be achieved in low SNR environments.

AFM/STM observations were performed on sub nm thick C-Au-S film by co-operation process of plasma CVD and sputtering with using CH4, SF6 and Ar mixture gas and Au plate discharge electrode. From the refractive index values, the conductive granular molecules with a size of 0.4-0.6 nm were expected to exist in the film. For the film at thickness similar to the molecular size, Ra (arithmetic mean departures of roughness profile from the mean line) values were measured to be 0.712/6.10 nm by AFM/STM measurement, respectively. The one order large STM Ra value compared to the AFM Ra value suggests that the film contains conductive granular molecules.

Seeding substrates with diamond nanocrystals has been considered to be a promising nondestructive pretreatment method for growth of diamond films. However, its application is strongly impeded by the segregation of diamond nanocrystals on substrates. In the present study, we suggest a very simple but effective seeding way ("sandwich" (SW) seeding way) to prevent nanocrystals from segregation. By the SW seeding way, the diamond nanocrystals can be nearly uniformly dispersed on Si substrates with the areal density of the order of 108cm-2. On the nano-seeded Si substrates the continuous and homogeneous diamond films can be successfully fabricated using a microwave plasma enhanced chemical-vapor-deposition (MPECVD) equipment. The cross-sectional transmission electron microscopy (TEM) images reveal that compare with the diamond films grown on the Si substrates pretreated by the conventional scratching method, the films deposited on the nano-seeded Si substrates present a much flatter interfacial structure, suggesting that the SW seeding way can effectively reduce the interface coarseness.

Electron emissions from single-crystalline diamond surfaces by internally exciting electrons from the valence to conduction bands have been investigated. Monte Carlo simulations have been employed to estimate the impact ionization rates of carriers in diamond under high electric fields up to 1107V/cm. The calculations demonstrate substantial impact ionization rates which rapidly increase with increasing electric fields above 8105V/cm. Highly efficient electron emissions with high emission current efficiencies of approximate unity have been attained from a MIS-type diamond layered structure that are composed of heavily ion-implanted buried layer (M), undoped diamond (I) and hydrogenated p-type diamond (S) with an emission surface of a negative electron affinity. The highly efficient emission mechanism is discussed in relation to the field excitation of electrons from the valence band to the conduction band in the undoped diamond layer and the carrier transport to the diamond surface.

In-situ position-controlled lateral deposition of nanometer-size Zn and Al dots on a sapphire substrate was accomplished by dissociating diethylzinc and trimethylaluminum using an optical near field on a sharpened optical fiber probe tip. The minimum diameters of the Zn and Al dots deposited were 37 and 25 nm, respectively, comparable with the apex diameter of the fiber probe. By changing the reactant molecules during deposition, nanometric Zn and Al dots were successively deposited on the same sapphire substrate with high precision. The distance between these dots was as short as 100 nm.

Carbon-gold (C-Au) film was formed by co-operation process of plasma CVD and sputtering with using methane and Ar mixture gas and gold plate discharge electrode. Refractive index of 3.1 for the film was obtained at Au atom content of 5.5 atomic%. The optical transmittance was improved significantly in the visible light wavelength range compared to the C-S-Au film reported previously. Au atom distribution in the C-Au film and the electronic polarizabilities were discussed in the relation to the refractive index.

Optical properties and growth of self-assembled quantum dots (SAQDs) for optoelectronic device applications are discussed. After briefly reviewing the history of research on QD lasers, we discuss growth of InAs SAQDs including the light emission at the wavelength of 1.52-µm with a narrow linewidth (22 meV) and the area-controlled growth which demonstrates formation of SAQDs in selected local areas on a growth plane using a SiO2 mask with MOCVD growth. Then properties of the InGaAs AQDs are investigated by the near-field photoluminescence excitation spectroscopy which reveals gradually increasing continuum absorption connected with the two-dimensional-like (2D-like) wetting layer, resulting in faster relaxation of electrons due to a crossover between 0D and 2D character in the density of states. In the coherent excitation spectroscopy, the decoherence time is determined to be about 15 ps, which is well explained by the phonon induced relaxation mechanism in the SAQDs. Finally, nitride-based SAQDs and perspective of QD optical devices are also discussed.

The long-term reliability of heterojunction bipolar transistor (HBT) continues to be a subject of great interest due to the increased acceptance of this device in a wide range of applications. The most demanding requirements for long-term reliability include high performance microwave instrumentation, X-band radar, and lightwave communication (OC-192). A significant leap in the long-term reliability performance was observed in HBT as the AlGaAs emitter material was replaced with lattice matched InGaP. A dramatic improvement in the long-term reliability was also observed in AlGaAs emitter HBT's as the turn on voltage (Vbe) was lowered. The typical failure mechanism in HBT devices at high current density and high temperature long-term reliability testing was a dramatic increase in the base current at low current densities. One of the limiting factors in obtaining MTTF in InGaP HBT was the long time required to promote failures in the HBT device. Furthermore, a large sample size is necessary to extract a reliable MTTF. Significant increases in the current density as high as 180 kA/cm2 during reliability testing was used to promote failures in order to obtain an MTTF within a reasonable amount of time. The MTTF at a junction temperature of 334C and at a current density of 180 kA/cm2 was 1159 hours. The extrapolated MTTF at a junction temperature of 150C exceeded 106 hours for all of the tested devices. An attempt to predict the MTTF of AlGaAs and InGaP HBT using a simple model based upon the fitting of the initial Gummel plots of large area devices was made. The model was based upon the estimation of the trap defect density at the base/emitter junction, the hole injection component of the base current, and the turn-on Vbe. Degradation of the HBT was assumed to occur at the base/emitter junction and this corresponded to an increase in the trap density at this heterojunction. A factor of 5 improvement in the MTTF of the reliability of AlGaAs HBT with a lower turn on voltage was estimated based upon the above model, which confirmed the experimental results. These results suggested that the emitter material is primarily responsible in determining the long-term reliability characteristics of HBT. The combination of a high effective hole barrier and a low turn-on Vbe are highly desirable for long-term reliability characteristics.

The chemical stability of the constituent elements in polycrystalline Sr-Bi-Ta-O thin film with various Bi content prepared by metalorganic chemical vapor deposition (MOCVD) was investigated by X-ray photoelectron spectroscopy (XPS). Moreover, that of the epitaxial films was also investigated to estimate the effect of the grain boundary in polycrystalline films. Therefore, only the Bi element drastically changed from Bi3+ state to Bi0 one by the Ar sputtering. This change increased with increasing the Ta/Bi mole ratio in the film from 0.64 to 1.67. This result was observed not only for the polycrystalline films but also for the epitaxial films, suggesting that this is the grain character not grain boundary one. The stability and the leakage character of the film strongly depend on the constituent of the film.

In this paper, we discuss the performance and computational complexity of modulo-type Viterbi decoder (MVD) for high-speed digital transmission applications. It is shown that the MVD, which is a combination of modulo operation and Viterbi decoder at the receiver, has the same performance as a conventional Viterbi decoder (CVD) with extended constellations. We also show by complexity analysis that the MVD in conjunction with the Tomlinson-Harashima (TH) precoder at the transmitter reduces the system complexity significantly as compared to the CVD. The performance of the digital subscriber line (xDSL) system employing the MVD is investigated in the presence of near-end crosstalk (NEXT) and impulsive noise.

Thin films of carbon (C)-sulfur (S) compound were formed by plasma CVD (PCVD) at the special chemical condition. The reactor has a parallel plate electrode system and was operated at a discharge frequency of 13.56 MHz with using a mixture gas of argon (Ar), methane (CH4) and SF6. The deposition was performed on a substrate placed on the grounded electrode. Atomic composition of the film was observed to depend on the gas mixture ratio. The sulfur atom density was increased up to 30% with using a mixture gas at a pressure of 0.1 Torr and at a flow rate of 20, 20 and 50 SCCM for Ar, CH4 and SF6, respectively. It was expected that the C-S compounds were deposited under the condition of F atom elimination by forming HF.

Our recent progress in GaN-based nanostructures for quantum dot (QD) lasers and vertical microcavity surface emitting lasers (VCSELs) is discussed. We have grown InGaN self-assembled QDs on a GaN epitaxial layer, using atmospheric-pressure metalorganic chemical vapor deposition. The average diameter of the QDs was as small as 8.4 nm and strong photoluminescence emission from the QDs was observed at room temperature. Furthermore, we found that InGaN QDs could be formed even after 10 QD layers were stacked, thus increasing the total QD density. Using these growth results, we fabricated a laser structure with InGaN QDs embedded in the active layer. A clear threshold was observed in the dependence of the emission intensity on the excitation energy at room temperature under optical excitation. We succeeded in demonstrating in lasing action in vertical cavity surface emitting lasers at room temperature with a cavity finesse of over 200.

A selectively grown Si1-xGex base heterojunction bipolar transistor (HBT) was fabricated, and effects of Ge and B profiles on the device performance were investigated. Since no obvious leakage current was observed, it is shown that good crystallinity of Si1-xGex was achieved by using a UHV/CVD system with high-pressure H2 pre-cleaning of the substrate. Very high current gain of 29,000 was obtained in an HBT with a uniform Ge profile by both increasing electron injection from the emitter to the base and reducing band gap energy in the base. Since the Early voltage is affected by the grading of Ge content in the base, the HBT with the graded Ge profile provides very high Early voltage. However, the breakdown voltage is degraded by increasing Ge content because of reducing bandgap energy and changing dopant profile. To increase the cutoff frequency, dopant diffusion must be suppressed, and carrier acceleration by the internal drift field with the graded Ge profile has an additional effect. By doing them, an extremely high cutoff frequency of 130 GHz was obtained in HBT with graded Ge profiles.

Heterojunction bipolar transistors (HBTs) are key devices for a variety of applications including L-band power amplifiers, high speed A/D converters, broadband amplifiers, laser drivers, and low phase noise oscillators. AlGaAs emitter HBTs have demonstrated sufficient reliability for L-band mobile phone applications. For applications which require extended reliability performance at high junction temperatures (>250) and large current densities (>50 kA/cm2), InGaP emitter HBTs are the preferred devices. The excellent reliability of InGaP/GaAs HBTs has been confirmed at various laboratories. At a moderate current density and junction temperature, Jc = 25 kA/cm2 and Tj = 264, no device failures were reported out to 10,000 hours in a sample of 10 devices. Reliability testing performed up to a junction temperature of 360 and at a higher current density (Jc = 60 kA/cm2) showed an extrapolated MTTF of 5 105 hours at Tj = 150. The activation energy for AlGaAs/GaAs HBTs was 0.57 eV, while the activation energy for InGaP/GaAs HBTs was 0.68 eV, which indicated a similar failure mechanism for both devices.