Filter-embedded design and its applications to passive components

A design in which a filter is embedded in a fiber fixed on a substrate is proposed. It was successfully applied to the fabrication of low loss fiber optic components for a single-mode fiber transmission system. These components have a wide operational temperature range. The design is easily adapted to a multifilter or multifiber component. Filter embedding is achieved in two ways. One is to insert a thin filter chip in a slit which is machined into a fiber fixed on a substrate by a dicing saw (filter inserted type). The other is to evaporate a filter film directly on a fiber end face and butt this fiber to another fiber on a guide groove on a substrate (filter evaporated type)     

Two-port active coupled microstrip antenna

A multilayer structure, based on a patch antenna coupled through a nonresonant slot to a pair of feeding microstrips is a versatile module which can be used as a radiating and resonating element in a number of different configurations. Direct connection to a low cost transistor in a feedback loop results in a very simple active antenna, as reported. Different termination conditions at the four microstrip ports give rise to a number of alternative configurations for active generation/detection and multipatch arrays.<>     

A Note on Loaded Line Synthesis (Correspondence)

The purpose of this note is to present an alternate derivation of a formula for the synthesis of a loaded line. The problem is to determine the values of the normalized susceptances a and c mounted an exact quarter-wavelength apart along a uniform line. These are arranged in the order a, c, c,. . .c, a to achieve a loaded line with a given phase shift and perfect match. In order to analyze a particular line design for standing-wave ratio and phase shift over a band of frequencies on a digital computer, it is worthwhile to know the values of the susceptances to many more decimal places than one would achieve from a simple graph.     

Virtual impedance control for a regional dynamic voltage restorer

A dynamic voltage restorer (DVR) can be installed in a middle-voltage (MV) power grid, to concurrently protect a cluster of sensitive loads from voltage sags. To further improve its efficiency and reduce the difficulty in its implementation, a novel control strategy for operating such a DVR as a virtual impedance in series with sensitive loads is proposed in this paper. In addition to its usual function of compensating for voltage sags, such a DVR can also operate as a virtual inductance, to function as a fault current limiter (FCL) during a downstream fault, or a virtual capacitance, to function as a series compensator (SC) to compensate the voltage loss along the feeder line during heavy load. Based on a dual-loop control design, strategies for operating a DVR as a series virtual inductance and a virtual capacitance are proposed, and methods for tuning the parameter values and a stability analysis of the whole system are presented. The feasibility and effectiveness of the proposed method are verified by simulations using the PSCAD software, and experimental results obtained using a prototype DVR are presented.     

A 220-MHz pipelined 16-Mb BiCMOS SRAM with PLL proportionalself-timing generator

This 512 Kw×8 b×3 way synchronous BiCMOS SRAM uses a 2-stage wave-pipeline scheme, a PLL self-timing generator and a 0.4-μm BiCMOS process to achieve 220 MHz fully-random read/write operations with a GTL I/O interface. Newly developed circuit technologies include: 1) a zig-zag double word-line scheme, 2) a centered bit-line load layout scheme, and 3) a phase-locked-loop (PLL) with a multistage-tapped ring oscillator which generates a clock cycle proportional pulse (CCPP) and a clock edge lookahead pulse (CELP)     

Equivalent transformations for the mixed lumped Brune-type sectionand uniform transmission line

As an analytical method for nonuniform transmission lines (NTLs) equivalent transformations are extended to a more general case, namely a mixed lumped Brune-type section and a uniform transmission line (unit element, UE). Circuits consisting of a cascade connection of a lumped Brune section and a UE are equivalent to one consisting of a cascade connection of a nonuniform transmission line whose characteristic impedance distribution is expressed with a trigonometric function and a lumped Brune section. This equivalent transformation method is easily applied to a circuit consisting of a lumped C section and a UE. The equivalent circuit is a circuit consisting of an NTL and a lumped C section. In this case, the characteristic impedance distribution of the NTL may be expressed in terms of a hyperbolic function. Exact network functions of the NTLs are easily obtained from the equivalent circuits without solving the telegrapher's equation. By considering the limiting case of these equivalent transformations, equivalent transformations for circuits consisting of a cascade connection of a lumped resonance circuit and a circuit and a uniform transmission line are derived     

WiFi access point pricing as a dynamic game

We study the economic interests of a wireless access point owner and his paying client, and model their interaction as a dynamic game. The key feature of this game is that the players have asymmetric information - the client knows more than the access provider. We find that if a client has a "web browser" utility function (a temporal utility function that grows linearly), it is a Nash equilibrium for the provider to charge the client a constant price per unit time. On the other hand, if the client has a "file transferor" utility function (a utility function that is a step function), the client would be unwilling to pay until the final time slot of the file transfer. We also study an expanded game where an access point sells to a reseller,which in turn sells to a mobile client and show that if the client has a web browser utility function, that constant price is a Nash equilibrium of the three player game. Finally, we study a two player game in which the access point does not know whether he faces a web browser or file transferor type client, and show conditions for which it is not a Nash equilibrium for the access point to maintain a constant price.     

In situ HREM study on the structural instability of isolated nanometre-sized alloy particles in the Sn-Bi system

The structural instability of isolated nm-sized alloy particles has been investigated by in situ transmission electron microscopy, using particles in the Sn-Bi system. In a pure tin (Sn) particle, no structural fluctuation was induced under electron-beam irradiation. In a tin-rich solid solution particle, an orientational fluctuation took place at a rate of approximately once per 1-3 s. In a high concentration alloy particle with a two-phase microstructure, a structural fluctuation occurred at a rate of a few hertz. Namely, the fluctuation became more frequent with increasing bismuth (Bi) concentration, no matter whether it consists of a single phase or multiple phases. A good parallelism can be found between this fluctuation enhancement with bismuth concentration and the fact that the free-energy difference between a solid particle and the corresponding liquid one decreases continuously with bismuth concentration and approaches a value close to zero at the eutectic composition. These results lead to a view that a nm-sized solid particle exhibits a structural instability under electron-beam irradiation when the free-energy difference between a solid particle and the corresponding liquid one is reduced to a value close to zero.     

A fast-settling CMOS op amp for SC circuits with 90-dB DC gain

A technique that combines the high-frequency behavior of a single-stage op amp with the high DC gain of a multistage design is presented. This technique is based on the concept that a very high DC gain can be achieved in combination with any unity-gain frequency achievable by a (folded-) cascode design. Bode-plot measurements for an op amp realized in a 1.6-μm process show a DC gain of 90 dB and a unity-gain frequency of 116 MHz (16-pF load). Settling measurements with a feedback factor of 1/3 show a fast single-pole settling behavior corresponding to a closed-loop bandwidth of 18 MHz (35-pF load) and a settling accuracy better than 0.03%. This technique does not cause any loss in output voltage swing. At a supply voltage of 5.0 V an output swing of about 4.2 V is achieved without loss in DC gain. The above advantages are achieved with a 30% increase in chip area and a 15% increase in power consumption     

High-speed driving method using bipolar scan waveform in AC plasma display panel

This paper proposes a new high-speed driving method using the bipolar scan waveform with a scan width of 1 /spl mu/s in an ac-plasma display panel. The bipolar scan waveform in an address period consists of a two-step pulse with two different polarities, i.e., a forward scan pulse with a negative polarity and reverse scan pulse with a positive polarity, which can produce two address discharges, including a primary address discharge for generating wall charges and secondary address discharge for accumulating wall charges. To produce the fast address discharge stably using the bipolar scan pulse during an address period, a new reset waveform is designed based on a V/sub t/ close curve analysis, and the address discharge characteristics examined under various reset and address waveforms. As a result of adopting the proposed driving method, a high-speed address with a scan width of 1 /spl mu/s is successfully obtained when using a checkered pattern on a 4-in test panel.     

A quad-rotor system for driving and flying missions by tilting mechanism of rotors: From design to control

This article presents the hybrid design and control of a quad-rotor system called Flymobile. Flymobile is a combined system of a mobile robot and a quad-rotor system aimed to perform both flying and driving tasks. Flymobile performs flying tasks in the same way as conventional quad-rotor systems while the tilting mechanism of each rotor allows Flymobile to navigate in its terrain for a driving task. The body frame with rotors is implemented by a calibration process through a test-bed equipped with a force sensor. The triangular wheel frame is designed to mimic motions of a mobile robot with three passive wheels. Sensor data of a gyro and an accelerometer are filtered and used for controlling the attitude of the system. Focusing on a practical approach of implementing a hybrid system, a non model-based approach is applied to control Flymobile. Experimental studies are demonstrated to show the feasibility of performing both driving and flying missions.     

Computer-aided design of a Si avalanche photodiode

A computer-aided design of a Si avalanche photodiode is presented. As an example, the design of the boron diffused photodiode with a desired time constant is carried out. The choice of an area of an active region is not affected by a diffusion condition but primarily by a substrate impurity concentration. For a very high speed response a moderate substrate impurity concentration must be selected. For a longer time constant than about 0.1 ns an increasing area of an active region is acceptable with a decreasing substrate impurity concentration. In a lightly doped substrate, a uniform multiplication of an active region cannot occur. Using the usual diffusion technique the acceptable highest resistivity of a substrate is about 1-2 Ω.cm. The capacitance of the guard ring occupies a considerable part in a total capacitance. Calculated results are in good agreement with experimental results.     

Thermoelectric Module Design Under a Given Thermal Input: Theory and Example

Established thermoelectric theory enables direct calculation of the power output and conversion efficiency if the temperature difference across a module is given. However, in some applications such as those using a radioisotope or solar radiation as a heat source, the thermal input remains constant while the temperature difference varies with the geometry of the thermoelectric module. In this paper, a theoretical framework for thermoelectric module design under a given thermal input is presented. It provides a convenient approach for module geometry optimization. The usefulness of the theory is demonstrated through a design study, in which an appropriate thermoelement length for a solar thermoelectric system is determined by considering conflicting requirements for a longer length to obtain a greater temperature difference and for a shorter length to produce a larger power output.     

Some Theoretic Results on a Digital EMG Signal Processor

As is well known, a general EMG signal processing scheme includes a prewhitening filter, a v-order detector, a smoothing filter, and a relinearizer. In this paper, a theoretical analysis of such a scheme is carried out, including a detector characteristic which presents a logarithmic behavior.     

Class of majority-logic-decodable codes with a minimum distance of 4

We prove that the (n = 4a2 + 4a + l, k = 4a2) binary code generated by 1+X2a+X2a+1+X4a+1 has a minimum distance of 4 and is 1-step majority-Iogic-decodable.     

Focusing characteristics of a wide-striped laser diode integratedwith a microlens

We developed a wide-striped laser diode integrated with a microlens that provides good focusing characteristics through a small focusing spot. We calculated and demonstrated that a 60-μm-wide core and a 1.9-μm-high ridge is the best structure for fundamental index-guiding mode oscillation of a wide-striped laser diode. We integrated a wide-striped laser diode with the developed microlens in the Fresnel diffraction held, and demonstrated that a device with a 60-μm-wide core has a minimum focusing spot width of 2.0 μm in the horizontal direction. Also, we estimated the wavefront in the Fresnel diffraction field from the working distance error of a lens designed for a collimated incident beam, and showed that the working distance error, focusing spot width, and sidelobe can be improved by this estimated wavefront     

Analysis of a strip in a waveguide

An analysis and an experimental study of a strip in a transverse plane of a rectangular waveguide below cutoff are presented. This work is a preliminary step in analyzing a stripline-fed slot antenna array in which each stripline feed is enclosed in a rectangular waveguide below cutoff. A numerical method is developed to solve a “pseudo” mixed-potential integral equation for the current on the strip excited by a delta-gap source at some point along the strip. The Green's function for dipole sources in the rectangular waveguide is used in the spectral and spatial representations and Shanks' transform is employed to speed up the convergence of the doubly infinite series. Numerical and experimental results are presented for a monopole fed at one wall of a rectangular waveguide and for a bottom-fed and bottom-loaded strip in a rectangular waveguide     

Bugged balls for tough calls [ball tracking systems]

This paper presents a soccer ball containing a transmitter that reveals the exact location of the ball on the pitch. It is a coin-size radio transmitter that broadcasts a pulsed signal in the 2.4 gigahertz band to a dozen receivers mounted on floodlight masts and near the sidelines. The receivers relay the pulses to a central computer, which then calculates the ball's exact location. The main goal of this transmitter is to help referees with tough calls, such as when a goalkeeper intercepts a ball on the fly after it has crossed the goal line. In such a case, the system would send a vibratory alert to a special wristwatch worn by the referee, signaling that the ball went over the goal.