藤田 孝之

In this paper, we propose a large-deflection electrostatic spiral-actuator with novel twisted-beams fabricated by surface micromachining. The stress-induced or bimetal-like actuators have merits of simple structure and fabrication steps with relatively large stroke. The novel stress-induced actuator presented here is composed of "twisted-beams", which have not only out-of-plane curvature but also rotation along its longitudinal direction. When the twisted-beams are used as components of a spiral actuator, the total stroke of the actuator becomes a sum of each deflection of the beams, and the stroke is much larger than conventional stressinduced spiral actuators. The experimental results of the spiral actuator show the maximum deflection of about 750 μm, which is extremely large for stress-induced-actuators.

多様化する無線通信方式に対応するため, 携帯電話などのマルチチャネル対応が進んでいるが, 今後, 各種無線機器のマルチチャネル化による小型軽量化を図るためには, 受動回路要素, ミクサ, 増幅器などのマルチチャネル化を実現することが必要である. 本論文では, マルチチャネル化にとって最も課題の多い能動回路, 特に増幅器のマルチチャネル化技術の現状を紹介するとともに, 筆者らが提案し, 開発を進めている低域通過チェビシェフ形インピーダンス変換回路を応用したマイクロ波2周波整合形デュアルバンドGaAs FET電力増幅器について, その現状と課題を紹介する.

We present design methodology, fabrication process and characterization of a dual-axis MEMS galvano-mirror with double gimbal structure. In the device, soft torsion beams are made of the photosensitive epoxy resin, SU-8, in order to obtain large-deflection angle for small driving power. In this paper, we present characteristics of the inner and outer mirrors for dynamic and static operation, and also test results for stability. The tilt angle of the mirror for applied static current is about 0.1 degrees/mA. Maximum deflection angle at resonant operation was measured to be over than +/- 40 degrees. (c) 2005 Elsevier B.V. All rights reserved.

In this paper, we present an MEMS gyroscope with double gimbal structure. The device has inner- and outer-gimbals with independent coils (inner- and outer-coils), and the gimbals are perpendicularly supported by torsion bars. In the parallel magnetic field, the reference vibration of the inner-gimbal is introduced by electromagnetic force from the inner-coil and displacement of the outer-gimbal by the Coriolis force is detected by electromotive force at the outer-coil. The device has no critical parts such as narrow gaps or comb drivers, and it requires less accurate alignment of the magnetic field. Since the device can operate in atmospheric pressure, a hermetic seal is not required. For stable operation, the device was combined with a semi-digital control circuit. The circuit has an overtone PLL oscillator, time-shared driving/detecting logic, a kind of adaptive band pass filters. The system showed excellent performance for angular rate detection. Additionally, the characteristics of the device operating in vacuum were also examined. (c) 2005 Elsevier B.V. All rights reserved.

A dual-band GaAs FET power amplifier with the two-frequency lumped-element matching circuits is designed using the low-pass Chebyshev-form impedance transformer design, method. An 800/1500MHz 1Watt-class GaAs FET amplifier is fabricated and the experimental results show the saturated output powers of 30.9dBm and 28.2dBm with the power added-efficiencies of 51.6% and 51.9% at 800MHz and 1500MHz, respectively. The fabricated circuit size is 24mm by 28mm. The presented design approach enables a simple dual-band power amplifier with superior performance and small size.

A rotational vibrating disk with a high Q value was proposed and applied to a micro gyroscope. This structure consists of a disk surrounded by four pendulums mounted at 90° increments. When rotationally resonant vibration is induced in the disk, there is an unmoving point on each arm of pendulums. When this point, a nodal point, is clamped, the vibratory energy loss was able to be reduced. This structure achieves a very high Q value of 85,000 in a vacuum. We used this rotational mode as a reference vibration for a vibratory gyroscope. The excitation of the vibration was induced by electrostatic forces. Electrodes were placed adjacent to the lower portion of the disk to measure the angular rate. The electrodes established a capacitance between themselves and the disk. The Coriolis force produces a displacement of the disk and this displacement varies the detection capacitance. Measuring the change in capacitance allowed for the measurement of the angular rate. This paper describes the design and fabrication of the proposed device along with some results and observations. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.

Recently, much attention has been given to Doherty amplifiers as microwave power amplifiers that have the possibility of realizing high efficiency and low-distortion characteristics with a wide dynamic range. In this paper, the configuration, operation, and characteristics of Doherty amplifiers are surveyed and challenges in their use as microwave power amplifiers are identified. The circuit condition for use as a microwave Doherty amplifier is derived. Based on this condition, a method for the design of a practical output coupling scheme for a Doherty amplifier is proposed. Also, the effects of the peak amplifier and the carrier amplifier composing a Doherty amplifier on the combining characteristics of the Doherty circuit configuration are studied and design guidelines are presented. The behavior and characteristics of the power Si MOSFET Doherty amplifier constructed with the proposed design method are discussed in detail by simulation. The evaluation results are presented for a 1-GHz Si MOSFET Doherty amplifier designed and fabricated on the basis of the simulation results. Finally, summaries and future challenges are given. (c) 2005 Wiley Periodicals, Inc.

最近,広ダイナミックレンジの高効率,低ひずみ特性を実現できる可能性のあるマイクロ波電力増幅器としてドハティ増幅器が注目されている.本論文では,まず,ドハティ増幅器についてその構成,動作,特性などの特徴,マイクロ波電力増幅器としての課題について紹介する.本論文では,マイクロ波ドハティ電力増幅器において成り立つ回路条件を導き,これを応用してドハティ増幅器の実用的な出力結合回路の設計法を提案する.また,ドハティ増幅器を構成するピーク増幅器及びキャリヤ増幅器の出力回路構成がドハティ回路構成の合成特性に及ぼす影響についても明らかにし,その設計指針を示す.提案した設計法を用いて構成した電力Si MOSFETドハティ増幅器の振舞い及び特性をシミュレーションにより詳細に検討する.また,これらの結果を踏まえて設計試作した1GHz帯Si MOSFET ドハティ電力増幅器についての評価結果を紹介する.最後に,まとめ及び課題を展望する.

We report a driving and movement detection system for a micro vibratory gyroscope with double gimbal structure. The gyroscope has two-coils on its outer and inner-gimbals and the inner-gimbal is vibrated by the electromagnetic force. Our system drives inner-coil and simultaneously detects the vibration of the inner-gimbal by time shared control. The system includes a PLL loop with an over-tone oscillator and PLD for achieving time-shared driveing/detection scheme. The system showed good characteristics for angular rate detection.

This paper presents the quantitative analysis and influence of CO2 dissolved in TMAH for silicon etching. The etching rate on the (100) plane increases at first and then decreases with the increase of CO2 concentration. The etching rate on the (110) plane decreases monotonously with the increase of CO2 concentration. Although the etching rate on the (110) plane is higher than that on the (100) plane at ordinary conditions, this relationship is reversed at a certain quantity of CO2 dissolution. The etch-stop appears at higher concentration of CO2 dissolution. It was confirmed that changes of the silicon etching characteristics are caused by concentration of carbonate anions. The CO2 dissolution has influence on the (100) plane and no influence on the (110) plane. Key words: MEMS, TMAH, Anisotropic Etching, Carbon Dioxide. © 2003, The Institute of Electrical Engineers of Japan. All rights reserved.

This paper deals with a monolithically integrated multi-sensor system for the intelligent data carrier (IDC) system. The system includes a three-dimensional accelerometer, pressure sensor, temperature sensor and humidity sensor as well as the peripheral circuitry for each sensor on one chip. The peripheral circuitry was designed to combine them to one-chip microprocessor with A/D converter. The monolithic multisensor chip was realized using an SOI wafer, where the Deep-RIE bulk-micromachining process and bipolar IC process were used for sensor device fabrication and circuit fabrication, respectively. The acquired data are logged on a nonvolatile memory and transmitted via TCP/IP protocol on the ethernet by the "embedded Linux board". We also show the remote monitoring system for multi-environmental sensor by using the graphical software and general purpose web browsing software. (C) 2002 Elsevier Science B.V. All rights reserved.

This paper presents a monolithically integrated multi-sensor system for the intelligent data carrier(IDC). The system includes a three-dimensional accelerometer, pressure sensor, temperature sensor and humidity sensor as well as the peripheral circuitry for each sensor on one chip. The peripheral circuitry was designed to combine them to one-chip microprocessor with A/D converter. The monolithic multi-sensor chip was realized using an SOI wafer, where the Deep-RIE bulk-micromachining process and bipolar IC process were used for sensor device fabrication and circuit fabrication, respectively.

In this paper, we present the vacuum-sealed vibrating gyroscope using silicon bulk micromachining technology. The size of the device is 12 x 12 x 1.4 mm(3). Two glass substrates hold the silicon sensing part. The sensing part is encircled with the silicon frame which forms hermetic seal with the glass substrates. From the results of initial testing, we obtain an angular rate detection sensitivity of approximately 8.9 mu V/(degrees s(-1)), a nonlinearity of 1.25% FS and a detection resolution of approximately 0.2 degrees s(-1) at 1 Hz BW. Additionally, we show the detection characteristics of the two orthogonal components of the applied angular rates simultaneously. (C) 2000 Elsevier Science S.A. All rights reserved.

Recently, many micromachined vibratory gyroscopes are proposed. Almost all the devices have been made efforts to obtain the double resonant mode in order to improve the sensitivity of micro gyroscopes. Nevertheless, there are some difficulty to obtain the accurate structure for consistent resonant frequencies between reference vibration and detection vibration in fabrication steps. In this paper, we show the design strategy of the high sensitive vibratory gyroscope using the hard spring effect positively. We propose the method for adjusting vibrating frequency and show the example of the actual device and some measured data for high performance devices.

In this paper, we present a novel micromachined galvano-mirror. In the device, the mirror structure is made of the fluorinated polymer (CYTOP<sup>®</sup>) in order to obtain high-speed response (i.e. light-weight mirror structure). The fluorinated polymer has a resistance to the anisotropic etchant, TMAH etc., the fabrication process becomes simple by using this polymer. The coil which makes torque to the mirror is made by electroplating metal, resulting in large cross-sectional area of the coil and enabling high current through the coil. We shows the fabrication process steps, measured mirror flatness and resonance characteristics.

Recently, micromachined vibratory gyroscopes are in the lime light. Especially, the double resonant mode is important in order to improve the sensitivity of micro gyroscopes. For such a purpose, some membrane structure of the micromachined gyroscopes have been reported. In this paper, we show the design strategy of the membrane spring for noting the resonance characteristics. In the paper, by measuring the fabricated devices and some simulations, we pointed out that the through knowledge of a nonlinearity of the membrane spring is important for micro structures.

In this paper, we present a novel micromachined galvano-mirror. In the device, the mirror structure is made of the fluorinated polymer (CYTOP™) in order to obtain high-speed response (i.e. light-weight mirror structure). The fluorinated polymer has a resistance to the anisotropic etchant, TMAH etc., the fabrication process becomes simple by using this polymer. The coil which makes torque to the mirror is made by electroplating metal, resulting in large cross-sectional area of the coil and enabling high current through the coil. We shows the fabrication process steps, measured mirror flatness and resonance characteristics. © 2000, The Institute of Electrical Engineers of Japan. All rights reserved.

Recently, many micromachined vibratory gyroscopes are proposed. Almost all the devices have been made efforts to obtain the double resonant mode in order to improve the sensitivity of micro gyroscopes. Nevertheless, there are some difficulty to obtain the accurate structure for consistent resonant frequencies between reference vibration and detection vibration in fabrication steps. In this paper, we show the design strategy of the high sensitive vibratory gyroscope using the hard spring effect positively. We propose the method for adjusting vibrating frequency and show the example of the actual device and some measured data for high performance devices. © 2000, The Institute of Electrical Engineers of Japan. All rights reserved.

Recently, micromachined vibratory gyroscopes are in the lime light. Especially, the double resonant mode is important in order to improve the sensitivity of micro gyroscopes. For such a purpose, some membrane structure of the micromachined gyroscopes have been reported. In this paper, we show the design strategy of the membrane spring for noting the resonance characteristics. In the paper, by measuring the fabricated devices and some simulations, we pointed out that the through knowledge of a non-linearity of the membrane spring is important for micro structures. © 2000, The Institute of Electrical Engineers of Japan. All rights reserved.

We have developed a novel rotational vibrating disk gyroscope using a silicon bulk micromachining technique. The vibrating disk is driven in the rotational direction by electrostatic force using comb finger actuator and is supported by four notched springs. The chip has the size of 8mm×8mm square, which includes the disk shaped vibrating mass with a diameter of 2mm and a thickness of 55μm. Additionally, we adapted the ASIC by using Multi-Chip Service (MICS/MCS) for signal processing. We finally obtained the sensitivity of 28μV/(deg/sec). © 1999, The Institute of Electrical Engineers of Japan. All rights reserved.

In micro mechanical devices with high aspect ratios, LIGA or LIGA-like processes are commonly used. In such a process, the material of the device structure is electroplated with nickel or copper because of ease of deposition. In this paper, an alternative material, electroplated nickel-tungsten alloy is examined as an MEMS material. Preliminary results of measurements of the mechanical, chemical and magnetoelectrical properties are shown and discussed. It is found that the Ni-W alloy film shows excellent characteristics such as low internal friction, high chemical resistance. © 1999, The Institute of Electrical Engineers of Japan. All rights reserved.

In this paper we present a prototype cross-shaped micro-gyroscope that detects two orthogonal components of the applied angular rates. From the results of initial testing, we obtain an angular-rate detection sensitivity of approximately 0.1 mV (rad s(-1))(-1) and detect the two orthogonal components of the applied angular rates simultaneously. Additionally, wt: designed the ASIC that acts as an interface circuit for our gyroscope. (C) 1998 Elsevier Science S.A. All rights reserved.

Recently, some types of micromachined gyroscopes (angular rate sensor) have been reported. Micromachined gyroscopes are suitable for familiar products such as a VTR, auto mobile and toy, where cost effective and mass production are required. However, it seems that many of problems and difficulties for designing the micro gyroscopes still remain. This study deals with such design problems on micromachined gyroscopes. The paper includes discussions about the analysis of the mass movement according to applied angular rate, optimum design respect to product of the sensitivity and response frequency, some problems in peripheral circuitry, acceleration sensitivity, a method to drive a mass, and a problems on the temperature dependence. © 1998, The Institute of Electrical Engineers of Japan. All rights reserved.

This paper deals with an analog integrated circuit for micro-machined gyroscopes with capacitive output. The Inte grated ciorcuit was fabricated as a part of the first project from the “Micromachining Multi-Chip Service Cooperative Re search Committee” organized by The Institute of Electrical Engineers Japan. This multi-chip service project offers a master slice chip with an equivalent of 9 blocks of operational amplifier circuits. Our integrated circuit includes a modulator, demodulator and synchronous rectifier for detecting small changes in the capacitance of a silicon gyroscope. In the paper, the experimental results of fabricated samples will be described. © 1998, The Institute of Electrical Engineers of Japan. All rights reserved.

In this paper we investigate the behaviour of a silicon-based angular rate sensor which uses a cantilever beam for the vibrating mass. To this end, we examine how the mechanical quality factor influences both the sensitivity and stability of the sensor in the absence of any feedback control. By way of analysis, a simple physical model is presented that describes both the relationship between the tuned device and its sensitivity and, also, how the stability of the device is affected by the various modes of the beam's vibration.