A Low-Power Dual-Band Triple-Mode WLAN CMOS Transceiver

This paper describes a 0.18-mum CMOS direct-conversion dual-band triple-mode wireless LAN transceiver. The transceiver has a concurrent dual-band low-noise amplifier for low power consumption with a low noise figure, a single widely tunable low-pass filter based on a triode-biased MOSFET transconductor for multi-mode operation with low power consumption, a DC-offset compensation circuit with an adaptive activating feedback loop to achieve a fast response time with low power consumption, and a SigmaDelta-based low-phase-noise fractional-N frequency synthesizer with a switched-resonator voltage controlled oscillator to cover the entire frequency range for the IEEE WLAN standards. The transceiver covers both 2.4-2.5 and 4.9-5.95 GHz and has extremely low power consumption (78 mA in receive mode, 76 mA in transmit mode-both at 2.4/5.2 GHz). A system noise figure of 3.5/4.2 dB, a sensitivity of -93/-94 dBm for a 6-Mb/s OFDM signal, and an error vector magnitude of 3.2/3.4% were obtained at 2.4/5.2 GHz, respectively     

10GHz GaAs JFET dual-modulus prescalar IC

A divide-by-256/258 dual-modulus prescalar IC has been successfully fabricated using enhancement-mode GaAs JFETs. The maximum operation frequency of 10.4 GHz is obtained by a 0.5 mu m gate length and buried p-layer JFET technology. The prescalar IC has sufficient operational margin to make it compatible with Si bipolar ECL circuits over a wide frequency range.<>     

Development of medium and small sized reactors: DMS

Nuclear power is expected to become the main source for electric power generation in Japan for the reasons of energy security and prevention of CO₂ emission. In addition, the slowdown of recent electric power demand and the liberalization of the electric power market are accelerating medium and small sized reactor development. (Hida and Ito, 2003) Furthermore, the needs of medium and small sized reactors have become greater in foreign countries where electric grid systems are weak. Under these circumstances, Hitachi has developed DMS's (Double MS: Modular Simplified & Medium Small Reactors) as 400 MWe class LWR's supported by The Japan Atomic Power Company. (Moriya et al., 2003) In addition, DMS's have been designed based on proven technology that requires no large-scale development, and can therefore be introduced in the market in near future.     

High-temperature strength and ductility increases of Ti-Mo-Al alloys by step aging

Step-aging programs, based on principles of particle-dislocation interactions, were developed systematically to obtain increases in the high-temperature strength and ductility properties of Ti-7 at. pct Mo-Al alloys. A triple-step aging program applied to Ti-7 Mo-16 Al produced a yield stress σ_0.2 = 1,500 MN/m², elongation to fracture ε _F = 4 pct at room temperature, and σ_0.2 = 900 MN/m², ε _F = 12 pct at 600°C. A two-step aging program resulted in σ_0.2 = 1,350 MN/m², ε _F = 5 pct at room temperature; σ_0.2 = 800 MN/m², ε _F = 20 pct at 600°C.     

An accurate HJFET capacitance-voltage model for implementation witha circuit simulator

We present a new accurate HJFET capacitance model to implement with a circuit simulator. This is an analytical model that describes capacitance-voltage (C-V) characteristics over a wide supply voltage range. The model for a capacitance component due to two-dimensional electron gas (2-DEG) conduction is based on gradual channel approximation, and takes into account the gradual capacitance transition near the threshold voltage. It also takes into account the field dependence of the 2-DEG mobility, which is very strong for deep sub-micron devices. The model for parasitic MESFET capacitance is based on the formula for a Schottky diode. Since the model consists of physical parameters, it provides feedback between the fabrication process and circuit design. The simulated results agree well with the measurements     

Small airway involvement in mixed connective tissue disease

We studied pulmonary functions in 17 female patients with mixed connective tissue disease (MCTD) to detect early pulmonary involvement in this disease; in 8 of the 17 patients follow-up studies were also performed at 1.2- to 5.9-year intervals. In the first pulmonary function tests, decreases in vital capacity (VC) and diffusing capacity (DLCO) were observed in 6 (35%) and 8 (47%) patients, respectively. The ratio of forced expiratory volume in one second to VC was normal in all the patients, but pulmonary resistance and static compliance were abnormal in 6 (35%) and 10 (59%) patients, respectively. However, frequency dependence of dynamic compliance was found in all 16 patients tested. Moreover, 4 (24%) of the 17 patients had normal DLCO and DLCO-to-alveolar volume ratio (DLCO/VA). Reductions in DLCO and DLCO/VA were significantly correlated with the disease duration. These results suggest that small airway obstruction is an early and frequent indication of functional pulmonary impairment, and that impairment of alveolar gas exchange is progressive in patients with MCTD.     

Development of self-vibration/detection AFM probe using quartz tuning fork

We present a novel type of quartz tuning-fork probe, which oscillates and detects its own probe deformation, for atomic force microscopy (AFM) systems. The quartz tuning-fork structure was fabricated using anisotropic wet etching, and a sharp tip was formed on a beam using a focused ion beam (FIB) system. We evaluated the vibration properties of the fabricated tuning fork with the tip structure in an anti-phase vibration mode and obtained a Q-factor value of 2.5 to 2.8 × 10³. This value was one order larger than that of a conventional Si probe. We experimentally clarified that the tuning-fork probe measured a 100-nm step of the Si surface, as well as the debris with a thickness of a few tens of nanometers on the surface by self-vibration and self-detection in cyclic-contact mode AFM. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Low-loss fibre-pigtailed 256 channel arrayed-waveguide gratingmultiplexer using cascaded laterally-tapered waveguides

A fibre-pigtailed 25 GHz-spacing 256 channel arrayed-waveguide grating (AWG) module has been fabricated. The module was composed of an AWG chip with a Δ of 1.5%, a fan-out planar lightwave circuit (PLC) with a A of 0.75%, an input fibre and two 128 fibre arrays. To improve the coupling loss of the 256 output fibres, a new PLC-fibre connection using cascaded laterally-tapered waveguides was developed. The fibre-pigtailing loss is reduced to only 1.1 dB and a multiplexer with a low insertion loss of 1.9-3.9 dB is realised