Large nonlinear optical effect in an InGaAs/InAlAs multiquantum well waveguide

All-optical refractive nonlinearity in a passive InGaAs/InAlAs multiquantum well waveguide is evaluated for TE and TM modes at 1.55 mu m wavelength and room temperature. A quarter wavelength change in the optical path length is observed at an input pump light power of 6.5 mW for 1.47 mu m wavelength in a 960 mu m long device. Nonlinear refractive index n/sub 2/ is evaluated to be -1.2*10/sup 6/ and -0.5*10-6cm/sup 2//W for the TE and the TM modes, respectively.<>     

DC voltage control strategy for a five-level converter

This paper describes a control method for a three-phase five-level diode-clamp pulse width modulation (PWM) converter considering DC-link capacitor voltage balancing problem. The proposed control circuit uses multiband hysteresis comparators (MHCs) to simplify the control of the main circuit. The DC-link capacitor voltage balancing problem is solved by changing the shape of the MHC. The proposed method can (1) overcome voltage imbalance at the DC-link capacitors; (2) achieve a unity power factor; (3) generate nearly sinusoidal input currents; and (4) regenerate electric power back to the power system. Simulation and experimental results demonstrate the validity of the proposed method     

Phase equilibria of Sn-In based micro-soldering alloys

The phase equilibria of Sn-In-X (X=Ag, Bi, Sb, Zn), the most basic information necessary for the development of Pb-free micro-soldering alloys, were studied using the CALPHAD method. Thermodynamic analyses for describing the Gibbs energies of the constituent phases were made by optimizing the obtained data on the experimental phase diagrams, and such data in the literature, including data on thermochemical properties. The present results combined with the thermodynamic database which was recently developed by our group [I. Ohnuma et al., J. Electron. Mater. 28, 1164 (1999)] provide various information on phase equilibria such as liquidus and solidus surfaces, isothermal and vertical section diagrams, mole fractions of the phase constitutions, etc., and thermodynamic properties such as activity, heat of mixing, surface energy, viscosity, etc., in multi-component soldering alloy systems including the elements of Pb, Bi, Sn, Sb, Cu, Ag, Zn, and In. Typical examples for the phase diagrams and thermodynamic properties of Sn-In-X ternary systems are shown. The application of the database to the alloy design for Pb-free solders is also presented.     

An approach for organizing knowledge according to terminology and representing it visually

We describe a term relation frequency (TRF) method for finding comprehensive documents in a rapidly growing academic discipline. The method enables us to organize knowledge into a single document based on terminology. The method is based on the classification of documents into comprehensive, central, peripheral, and independent classes according to the commonality and exclusiveness of terminology. Being able to find the documents quickly is helpful for our understanding of the discipline. Multiple-meaning technical terms such as "coordination" play a key role in rapidly growing academic disciplines such as coordination science. Visual representation of the multiple-meaning terms helps us to identify quickly and easily how the terms are used. With TRF and visualization methods, we can identify documents that explain a technical term comprehensively. We can also identify a change in the subject of a discipline according to when the comprehensive documents are written. We show that the observed change matches our understanding of the topic of the field "coordination science." The methods discussed here are promising to help us quickly understand and advance research in rapidly growing academic disciplines such as coordination science.     

Wafer-Level Integration Technique of Surface Mount Devices on a Si-Wafer With Vibration Energy and Gravity Force

This paper reports about a novel wafer-level integration technique of discrete surface mount devices (SMDs). It enables wafer-level mounting of plural kinds of SMDs on a silicon (Si)-wafer using vibration and gravity force. Deep holes with 400-m depth are formed on the surface of a Si-wafer by deep reactive ion etching process after general integrated circuit process for positioning of SMDs. A non-conductive adhesive (CYTOP) are coated on the deep holes and it is used to fix the aligned SMDs. SMDs are distributed on a Si-wafer mounted on vibration generator, and then a vibration is applied. The SMDs migrate due to the reduced friction between the wafer surface, and they drop into the holes on the silicon wafer. The size of the holes has an appropriate clearance to the size of SMD. In order to align two or more kinds of SMDs, sizes of the deep holes on a Si-wafer are adjusted to the size of each SMD. SMDs with the largest size are dropped into the holes first, and then the secondary large SMDs are dropped into the holes with the corresponding size. SMDs are finally connected electrically by wire bonding at the final step. In the experiment, two different sizes of SMD were successfully mounted into all the holes on a Si-wafer automatically. This technology will be a wafer-level process technology which is very promising to integrate two or more kinds of discrete elements.     

Phase equilibria and thermodynamic properties of Sn-Ag based Pb-free solder alloys

We have recently developed a thermodynamic database for micro-soldering alloys, alloy database for micro-solders (ADAMIS). ADAMIS which consists of the elements Ag, Bi, Cu, In, Pb, Sb, Sn, and Zn has been constructed by the calculation of phase diagrams (CALPHAD) method. The thermodynamic parameters for describing the Gibbs energy of the liquid and solid phases have been evaluated by optimizing the experimental data on phase boundaries and thermo-chemical properties. In this paper, the phase equilibria and the related thermodynamic properties pertaining to the Sn-Ag-X (X=Bi, In, Cu, and Zn) alloys are examined using ADAMIS. Typical examples of the isothermal and vertical section phase diagrams, liquidus surface, etc. for these promising lead-free solders are presented. In addition, ADAMIS is also applied to calculate the nonequilibrium solidification process using the Scheil model.     

10 Gbit/s optical BPSK homodyne detection experiment with solitaryDFB laser diodes

Solitary DFB laser diodes with 174 kHz beat linewidth are applied to a 10 Gbit/s optical BPSK homodyne detection system for the first time: a sensitivity of -38.9 dBm was achieved. A three-electrode laser forms the local oscillator and is modulated with a partial push-pull scheme to improve its frequency response     

Dynamic Power Integrity Control of ATE for Eliminating Overkills and Underkills in Device Testing

This paper proposes a power integrity control technique for dynamically controlling power supply voltage fluctuations for a device under test (DUT), and demonstrates its effectiveness for eliminating the overkills/underkills due to the difference of power supply impedance between an automatic test equipment (ATE) and a practical operating environment of the DUT. The proposed method injects compensation currents into the power supply nodes on the ATE system in a feed-forward manner such that the ATE power supply waveform matches with the one on the customer’s operating environment of the DUT. A method for calculating the compensation current is also described. Experimental results show that the proposed method can emulate the power supply voltage waveform under a customer’s operating condition and eliminate 95 % of overkills/underkills in the maximum operating frequency testing with 105 real silicon devices. Limitations and applications of the proposed method are also discussed.     

Novel grounded and floating high order immittance simulators using OTAs and OAs

This paper proposes novel grounded and floating high order series and parallel immittance simulators using operational transconductance amplifiers (OTAs) and operational amplifiers (OAs) with a finite gain–bandwidth (GB) product. They are composed of active devices (OTAs and OAs) and resistances, and are suitable for monolithic implementation in either CMOS or bipolar technologies. They also realize both positive and negative high order immittances. The circuit characteristics can be electronically tuned by adjusting the transconductances of OTAs and the GB products of OAs. Any transfer functions are realizable using the proposed simulators. Two examples are shown, together with simulation results.     

Analogue MOS current-mode circuits for three-dimensional integrated smart image sensor

An image processing technique using analogue MOS current-mode circuits is presented. This approach is of interest in smart image sensors based on three-dimensional (or multi-layered) VLSI structures. High-performance smart image sensors with high resolution can be realised because the number of transistors required for image processing in each pixel is greatly reduced.<>