A new silicon capacitive pressure sensor with center clamped diaphragm is presented. The sensor has a silicon-glass structure and is fabricated by batch-fabrication processes. Since deformed diaphragm has a doughnut-shape, parallel-like displacement is realized and therefore better linearity of 0.7% which is half of the conventional flat diaphragm sensor is obtained. It is clarified both analytically and experimentally that the capacitive pressure sensor with center clamped diaphragm is advantageous in terms of linearity.

We have developed and operated a newly conceived multiprobe scanning force microscope (SFM) using microfabricated piezoelectric cantilevers. An array of piezoelectric microcantilevers with a piezoelectric ZnO layer on an SiO2 film makes it possible to build a multiprobe SFM system. Multiprobe SFMs are required for the application of SFM to the probe lithography and high density data storage. Each cantilever probe of multiprobe system should have a detector for sensing of its own deflection and an actuator for positioning of its tip. The piezoelectric cantilever can detect its own vibration amplitude by measuring the piezoelectric current, and it can also drive its tip by applying a voltage to the piezoelectric layer. Therefore, the piezoelectric cantilever is suitable for each cantilever of the array in the multiprobe SFM. We have verified the applicability of the piezoelectric cantilever to each lever of the array by characterizing the sensitivities of the deflection sensing and actuation. The ZnO piezoelectric cantilever with the length of 125 µm works as the z scanner with the sensitivity of 20 nm/V. We have also fabricated an experimental piezoelectric microcantilever array with ten cantilevers. We have constructed parallel operation SFM system with two cantilevers of the fabricated array and successfully obtained parallel images of 1 µm pitch grating in constant height mode.

Photovoltaic devices capable of generating more than 200 volts with an area of 1 cm2 have been developed for directly driving microactuators such as piezoelectric or electrostatic actuators. The micro-devices interconnect 285 micro cells (unit cell size: about 0.5 mm 2.0 mm) in series, and have an open circuit voltage (Voc) of 207 volts, a short circuit current (Isc) of 36.6 µA, a maximum output power (Pmax) of 4.65 mW and a fill factor (F.F.) of 0.615 under AM (Air Mass) 1.5 and 100 mW/cm2 illumination. This voltage is the highest in the world for the area of 1 cm2. The series connection is precisely processed by a focused laser beam, thereby significantly reducing the area needed for device connections. It has been confirmed that a piezoelectric polymer can be directly driven by the electrical output in evaluating the potential of the devices to be used as a microactuator's power source.

High-end graphic systems with 3 million pixels require 8-bit D/A converters with more than 300-MS/s conversion rate. Furthermore, D/A converters need to operate with low supply voltage when they are integrated with large-scale digital circuits on a harf-micron CMOS process. This paper describes a 350-MS/s 8-bit CMOS D/A converter with 3.3-V power supply. A current source circuit with a delayed driving scheme is developed. This driving scheme reduces a fluctuation of internal node voltage of the current source circuit and high-speed swiching is realized. In addition to this driving scheme, two stages of latches are inserted into matrix decoder for reducing glitch energy and for enhancing decoding speed. The D/A converter is fabricated in a 0.5-µm CMOS process with single poly-silicon layer and double aluminum layers. Its settling time is less than 2.4 ns and it successfully operates at 350 MS/s.

In accordance with the diffusion of applications, such as the Desk Top Publishing system, the Document Formatting system and the Document Editing system, it is easy to make a document by using a computer. However, as for allocating the diagrams (figures and tables), there are few document processing systems able to allocate diagrams on the appropriate places automatically. In a document processing system it is a very important issue to allocate diagrams on the most suitable places. This paper defines the criteria for allocating diagrams on the suitable positions by investigating published papers. These criteria concern 1) the order of diagrams to be allocated, 2) the stability of the diagram allocations, 3) the distance between the diagram and the location of the corresponding first reference in the text, 4) the allocation balance of diagrams in a text, 5) the restricted areas where diagrams shouldn't be allocated, 6) the allocation priorities between diagrams of different width. Moreover, this paper proposes a method for deciding the diagram allocations satisfying the above criteria automatically and fast on document formatting systems. In this case we have limited its application to one type of ducuments, which is papers. Especially, this method can skillfully allocate diagrams of different width on the page by reallocating the diagrams and texts within it, and can allocate diagrams over the document uniformly.

This paper investigates the problem of constructing a logical multicasting tree which dispatches data to multiple destinations according to their bandwidth requirements. An optimization problem is formulated to minimize the maximum delay between a sender and multiple receivers. An algorithm of finding the optimum branching locations is presented. Performance analysis from the closed queueing network theory is given to evaluate a multicasting tree network based on this proposed algorithm.

We have designed a new current-mode low-voltage, low-power, high-frequency CMOS VCO circuit. The main purpose of this new circuit is to obtain operational capabilities with more than 1 GHz oscillation frequency from one battery cell. The current-mode approach was adopted throughout the circuit design to achieve this. New differential-type delay cells in the current-mode operation enable extremely low supply voltage operation and superior linearity between the oscillation frequency and control voltage of a ring oscillator. A design which combines the transitions of each delay cell output enables the VCO's high-frequency operation. To obtain a sufficient current level at output, a current amplifier with a small amount of positive feedback is used. The unnecessary generation of spectral components caused by mismatched time delay of delay cells in a ring-oscillator, which is an inherent problem of the VCO in a ring-oscillator form, is 0also analyzed. The characteristics of the designed VCO were examined by the SPICE circuit simulation using standard CMOS 0.6µm devices. Operation with a 1 V power supply, 1 GHz oscillation frequency, and 5.7 mW power dissipation was verified.

We show that the truth of a prenex normal form Presburger sentence bounded only by existential quantifiers (or an EPP-sentence) involving two variables can be decided in deterministic polynomial time. Specifically, an upper bound of the computation for the decision is O(n3u), where n is the number of atoms of the EPP-sentence, and u is the largest absolute value of all coefficients in the EPP-sentence. In the analysis for the upper bound, the random access machine is assumed for the machine model. Additionally, a uniform cost criterion is assumed. Deciding the truth of an EPP-sentence is an NP-complete problem, when the number of variables is not fixed. Furthermore, whether the truth of an EPP-sentence involving two or more variables can be decided in deterministic polynomial time, when the number of variables is fixed, or not has remained an open problem. We previously proposed a procedure for quickly deciding the truth of an EPP-sentence on the basis of a suggestion by D.C.Cooper. We found the upper bound by analyzing the decision procedure. The procedure can be applied to both automated correctness proof of specification in various design fields and detection of infeasible paths in a program. In the procedure, a matrix denoting coefficients of the variables in the EPP-sentence is triangulated.

Many efforts are currently underway to design wideband mobile communication systems. In this letter, we clarify the received signal level characteristics for wideband mobile radio channels in line-of-sight (LOS) microcells. We conduct several urban-area field experiments to measure the received signal levels for various receiver bandwidths from 300 kHz to 30 MHz and the power delay profile. The experimental results show that the fading depth of the received signal decreases as the normalized rms delay spread, defined as the product of receiver bandwidth and rms delay spread, increases. These results are useful in designing wideband microcell systems for urban areas.

This paper presents algorithms for computing the Minkowski sum of two polygons P and Q for a family of problems. For P being convex and Q being monotone, an algorithm is given with O (nm) time and space complexity. For both P and Q being monotone polygons, an O (nm log nm) time algorithm is presented and it is shown that the complexity of the sum is Θ (nmα(min(n,m))) in the worst case, where α() is the inverse of Ackermann's function. Finally, an O ((nm+k)log nm) time complexity algorithm is given when P is monotone and Q is simple, where k in the worst case could be Θ(n2m). The complexity of P Q is shown to be Θ(n2m) in the worst case. Here, m and n denote the number of edges of P and Q, respectively.

A new GSM data protocol called high speed circuit switched data (HSCSD) have been developed by European Telecommunications Standards Institute (ETSI) for high speed file transfer and mobile video applications. HSCSD increases data rate by using multiple TDMA time slots (up to 8) instead of one time slot in the current GSM implementation. The problem of multiple time slot assignment is that blocking rate of the system will increase. This problem can be solved by flexible resource assignment where the service specifies the maximum and the minimum capacity. Based on the current available capacity of a base station, a user will be assigned any rate between the maximum and the minimum capacities. This article describes HSCSD protocol and presents four radio resource allocation strategies for HSCSD: always allocates maximum, always allocates minimum, allocates maximum unless available resources are not enough, and allocates resources according to the current blocking statistics of the base station. A simulation model is proposed to investigate the performance of these algorithms. The blocking probability, the call completion probability, and the quality of service are used to evaluate the effects of algorithms in different system behaviors.

Recently, torque-transmission one-way tip articulated fiberscopes with a working channel have been developed. With this type of scopes, force is transmitted from the operator's hands to the tip of the fiberscope to obtain an adequate field of view. Micro actuators are expected to increasingly replace the operator's hands. Shape memory alloy (SMA) coil spring actuators are well suited to this purpose because of their large displacement compared with conventional actuators. In the fabrication of SMA coil springs, we examined fabrication conditions such as the tension and pitch of the SMA wire. As a result, we have successfully fabricated coil springs with a minimum outer diameter of 76 µm. SMA wire 25 µm in diameter and stainless steel wire 30 µm in diameter were used. As an application using SMA actuators, an active fiberscope (using an image guide fiber with 4200 pixels and light guide fibers) 2 mm in outer diameter with SMA actuators was designed and fabricated. We investigated the mechanical properties of the bending part in designing the SMA actuators. The specifications of the SMA coil springs are determined by the displacement and the force required of the pull wire. The relationship between the displacement of the pull wire and the number of windings of the SMA coil spring was calculated. The effective number of windings of SMA coil spring was found to be seventeen when using wire of 0.3 mm in diameter. The tip of the fiberscope was bent approximately 60 degrees and returned to the straight position when a current was applied to each of the SMA coil springs. A clear picture of the fiberscope which followed the tip bending operation could be received on the monitor. This SMA actuator can be easily extended for bending in many directions by configuring several of these mechanisms.

A thermally controlled magnetization actuator (TCMA) is proposed for micro-mechanical relays. It is actuated by changing the local magnetization of the structure by remote heating using a laser beam. It is fabricated by nickel surface micromachining (a fabrication technique using nickel electroplating). The optical power of the laser diode used to drive the TCMA is about 30 mW. The switching time of the microrelay was experimentally measured to be 10 ms, the same as that of a conventional mechanical relay. The contact force was calculated to be 20 µN, which can be improved by increasing the size of the TCMA.

A light emitting diode (LED) array unit for use as a light source in isolated power transmission and a display panel was fabricated using LED chips mounted on a silicon microreflector. The reflector was formed on a (100) silicon wafer by anisotropic chemical etching. An isolated power supply consisting of an infrared LED array unit and single silicon crystal solar cells had a maximum transmission efficiency of 2.3%. The silicon microreflector absorbs the heat generated by the LED chips and improves their light directive characteristics. A small, high-resolution, full color LED display panel can also be constructed using LED array units fabricated on silicon microreflectors. The LEDs in a unit are arrayed with a matrix structure and the electric contacts between the LED chips, the reflector and the upper cover glass are formed using conducting silver resin.

A method is proposed for forming hillock-free aluminum-based alloy bus lines for active-matrix liquid-crystal displays (LCDs). Aluminum (Al)-based alloy films are deposited using an Al target containing boron (B) or nickel (Ni) in a sputtering ambient containing nitrogen. The Al-Ni films deposited using an Al target containing Ni showed excellent hillock resistance: virtually no hillock formation after thermal treatment at around 400 and no significant increase in resistivity. These films also showed good patternability with a simple wet etching: a smooth line edge and a gently tapered profile. These films are thus suitable for the bus lines of active matrices.

Resonance characteristics of a coupled dielectric resonator which consists of a Whispering Gallery mode dielectric disk resonator and a ring resonator located eccentrically are analyzed. New analytical results of resonance characteristic based on the distributed coupling phenomena between the disk and the ring are obtained. The resonance performances have also been verified experimentally on X band model. We have found that Free Spectral Range of the coupled resonator is several times larger than that of the single disk resonator and the single ring resonator, respectively. As a result, the eccentric coupled resonator discussed in this paper can be used as a frequency selective element in millimeter wave integrated circuits.

A low power dual modulus prescaler for frequency synthesizers has been designed in a standard 1.2 µm digital CMOS process using enhancement source coupled logic (ESCL). Being a differential low amplitude current mode logic, ESCL has two interesting characteristics for this design besides low power consumption: the low noise performance, that allows this circuit to be on the same chip with sensitive analog circuitry, and the ability to run with a 200 mV sinusoidal signal as generated from an LC oscillator without the need of a clock amplifier. At 195 MHz and 3 V supply, the current consumption of the prescaler is as low as 289 µA, while maximum operating frequencies of 910 MHz at 5 V and 650 MHz at 3 V are achieved.

This paper describes a new timing circuit design technique for asynchronous burst-mode data transmission such as Fiber-To-The-Home (FTTH). It enables to the handling of asynchronous burst-mode data. Without an external reference clock signal, it can make a quick extraction of clock signal from received data packets using a "gating-timing circuit" and a "burst PLL." The gating-timing circuit employs bit gating for a quick phase response, and the burst PLL employs frame gating for quick frequency adjustment to differences between packets and clock extraction. This circuit has a simple configuration without any external oscillators, which reduces both cost and power. A fabricated 0.5-µm CMOS IC exhibits instantaneous response within one bit for 156 Mb/s asynchronous data packets.

Competition in some telecommunication services has emerged in Japan since deregulation of telecommunication markets in 1985. Demand forecasting methods which take into account competition and investment plan based on it should be studied. There are many forecasting and network planning methods, but most of them do not take into account competition. Thus, in this paper, the competitive Bass model, attraction model, regression model and entropy model are discussed as forecasting methods which can be used under competitive environment. Most of the existing planning methods have treated costs and interest rates as deterministic values, but in fact they are not deterministic. Thus, we show a method which represents undefined factors by fuzzy numbers with triangular membership functions.

Significant traffic variations occur in telecommunication networks. This paper focuses on hour-to-hour traffic variations during 24 hours and investigates the possibility of using idle periods effectively by introducing non-realtime service at a discount rate. In order to provide non-realtime service, memory is placed at each telecom center. When immediate service is not available, messages of non-realtime calls are stored in the memory and served later when network resources are available. Realtime calls are served with preference. A basic model and a method of dimensioning the memory capacity are presented. The basic model is extended to the network model, and methods of designing a minimum cost network and pricing and profit issues are presented. The results for a basic model are verified by traffic simulation. Numerical examples are given to show the effectiveness of non-realtime service.