1-V power supply high-speed digital circuit technology withmultithreshold-voltage CMOS

1-V power supply high-speed low-power digital circuit technology with 0.5-μm multithreshold-voltage CMOS (MTCMOS) is proposed. This technology features both low-threshold voltage and high-threshold voltage MOSFET's in a single LSI. The low-threshold voltage MOSFET's enhance speed performance at a low supply voltage of 1 V or less, while the high-threshold voltage MOSFET's suppress the stand-by leakage current during the sleep period. This technology has brought about logic gate characteristics of a 1.7-ns propagation delay time and 0.3-μW/MHz/gate power dissipation with a standard load. In addition, an MTCMOS standard cell library has been developed so that conventional CAD tools can be used to lay out low-voltage LSI's. To demonstrate MTCMOS's effectiveness, a PLL LSI based on standard cells was designed as a carrying vehicle. 18-MHz operation at 1 V was achieved using a 0.5-μm CMOS process     

A mechanical model to predict elastic-plastic fracture toughness in high strength materials

A mechanical model of crack initiation and propagation, which is based on the actual mechanism of ductile fracture in high strength materials, is proposed. Assuming that a crack initiates when the equivalent stress at a distance ρ from the crack tip reaches a critical value $\text{}\text{?}$gsf, an equation for predicting fracture toughness J_IC is obtained. From comparison between the predicted values and the experimental results, it is found that the distance ρ corresponds to the spacing of micro-inclusions. The temperature dependence of fracture toughness J_IC estimated according to the derived equation is given in an Arrhenius form of equation and is nearly consistent with the experimental results.     

An image sensor which captures 100 consecutive frames at 1000000 frames/s

An image sensor for a video camera of 1000000 frames per second (fps) was developed. The specifications of the developed sensor are as follows: 1) frame rate: 1000000 fps; 2) pixel count: 81 120 (=312/spl times/260) pixels; 3) total number of successive frames: 103 frames; 4) gray levels: 10 b; and 5) open area of each pixel (fill factor): 580 square micrometers (13%). The overwriting function is installed for synchronization of image capturing with occurrence of the target event. Sensitivity is significantly high with the large photogate. Some innovative technologies were introduced to achieve ultrahigh performance, including slanted linear CCD in situ storage, curving design procedure, and a CCD switch with fewer metal shunting wires. They are applicable to the development of other new high-performance image sensors.     

Thermionic-emission-based barrier height analysis for preciseestimation of charge handling capacity in CCD registers

In designing charge-coupled device (CCD) image sensors, it is essential to be able to estimate charge handling capacity. Because electrons have thermal energy, storing electrons in a well in a CCD register requires a sufficient potential barrier height to keep them from overflowing. As the quantity of electrons in a well depends on the barrier height, knowledge of this height is indispensable for precise estimation of the charge handling capacity. The authors have derived an expression describing the barrier height on the basis of thermionic emission, assuming current coefficient I₀ and well capacitance C. We derived the current coefficient I₀ and well capacitance C with computer simulations and from the results estimate the magnitude of the barrier height for a typical Vertical-CCD (V-CCD) structure. We have also examined barrier height dependence on structural parameters. Finally, we determined the barrier heights experimentally, and our results support the values obtained in the simulation     

Three-Dimensional Wave Optical Simulation for Image Sensors by Localized Boundary Element Method

A novel wave optical simulation method [a localized boundary element method (BEM)] has been developed. This method enables us to execute 3-D wave optical simulation with much smaller memory space and much shorter calculation time than conventional BEMs or finite-difference time domain methods. The light gathering power dependence on cell size and microlens height and distance, the color shading characteristics of inner lens structures, and the light gathering power and cross talk of light waveguide were analyzed by this method. A smaller cell needs a shorter focal length microlens, which can be realized by inner lens structures in CCD or the waveguide structures in CMOS image sensors. It is shown that this method can optimize these structures by calculating the color shading dependence on the microlens shape and the cross talk dependence on the waveguide materials. This method was found to be powerful and useful for the 3-D wave optical analysis of image sensors.     

Development of 28?GHz and 77?GHz, Mega-Watt Gyrotrons for Fusion Devices

A 28 GHz 1 MW with TE_8,3 cavity for GAMMA10 tandem mirror and a 77 GHz 1.5 MW gyrotron with TE_18,6 for Large Helical Device (LHD) have been developed to upgrade their Electron Cyclotron Heating (ECH) systems. In the 28 GHz gyrotron, the maximum power of 1.05 MW was obtained, which is in agreement with its design target value. And the high efficiency of 40% without collector potential depression (CPD) was obtained with 0.8 MW. In the first and second 77 GHz gyrotrons, 0.8 MW 3.6 sec., 0.3 MW 60 sec operations have been achieved, but several issues due to the stray RF and velocity dispersion have been found, too. In consideration of these, the design improvement was performed to aim at 1.5 MW in the third tube. In the short pulse test, the maximum output power of 1.6 MW and the maximum total efficiency of 49.4% with CPD were obtained. In the long pulse test, the pulse length extended to 5 sec with 1 MW, 1800 sec with 0.1 MW, 1.6 sec with 1.5 MW. Total injection power of 3.1 MW to LHD plasma has been achieved. It is shown that the electron beam pitch factor ?? decreases with increasing of beam current, comparing with the experimental and calculation results.     

Association study between Apolipoprotein L and schizophrenia by exhaustive and rule-based combination analysis for identification of multilocus interactions

Several single marker association and haplotypic analyses have been performed to identify susceptible genes for various common diseases, but these approaches using candidate genes did not provide accurate and consistent evidence in each analysis. This inconsistency is partly due to the fact that the common diseases are caused by complex interactions among various genetic factors. Therefore, in this study, to evaluate exhaustive genotype or allele combinations, we applied the binomial and random permutation test (BRP) proposed by Tomita et al. [IPSJ Digital Courier, 2, 691-709 (2006)] for the association analysis between an Apolipoprotein L gene cluster and schizophrenia. Using the seven selected representative single nucleotide polymorphisms (SNPs) based on the results of linkage disequilibrium evaluation, we analyzed 845 schizophrenic patients and 707 healthy controls, and investigated the validation of risk and protective factors with two randomly divided data sets. A comparative study of a method for analyzing the interactions was performed by conventional methods. Even if all the tested methods were used for analysis, the risk factor with a high significance was not commonly selected from both independent data sets. However, the significant interactions for the protective factor against disease development were commonly obtained from both data sets by BRP analysis. In conclusion, although it is considered that the causality of schizophrenia is too complex to identify a susceptible interaction using a small sample size, it was suggested that the healthy controls tend to have the same combination of certain alleles or genotypes for protection from disease development when BRP as a new exhaustive combination analytical method was used.     

Design and implementation of a digital filter for beat-by-beatimpedance cardiography

A digital filter for thoracic impedance cardiography was developed and implemented on a 16-bit personal computer after examining the effect of respiratory movement on the first derivative of the thoracic impedance signal. Four male subjects exercised with a cycle ergometer at 100 and 150 W successively, after resting for 5 min. Thoracic impedance and its first derivative (dZ/dt) were recorded by a standard four-electrode cardiograph. The peak-power spectral densities of the pneumogenic (P_p,c) and the cardiogenic (P_p,c) components of dZ/dt were separated with a simultaneous recording of the ECG and thoracic circumferences. P_pP_c increased with each increment of work rate: 0.12 (0.05-0.19) at rest, 0.67 (0.49-0.97) at 100 W, and 0.97 (0.58-1.52) at 150 W     

New empirical relation for MOSFET 1/ƒ noise unified over linear and saturation regions

This paper proposes an empirical relation, which represents 1/ƒ noise bias condition dependence for a silicon N-channel MOSFET. No matter whether the MOSFET is operated in linear or saturation region, bias condition dependence is found to be well described by a power function of voltage gain. By introducing a device's intrinsic 1/ƒ noise emf v_nc(ƒ), which is independent from bias condition, and empirical parameter β, input-referred 1/ƒ noise voltage v_ni(ƒ) is clarified to be a function of v_nc(ƒ), β, and voltage gain g_m/g_DS, i.e. v_nc(ƒ)(g_m/g_DS)^β−1. This relation implies that 1/ƒ noise voltage depends implicitly on bias condition through voltage gain, because transconductance g_m and drain-source differential conductance g_DS depend on bias condition. If β − 1 value is negligible, v_ni(ƒ) = v_nc(ƒ) is almost independent from bias condition, whereas, if β − 1 value is not negligible, bias condition dependence for v_ni(ƒ) appears to be observed. The β deviation from unity, which characterizes bias condition dependence, measures the difference between signal amplification and 1/ƒ noise amplification.