• Electronics and Telecommunications Trends
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• v.28 no.5
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• pp.83-92
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• 2013

IT 기술이 발달함에 따라 저전력, 초소형 센서노드를 설치하여 무인으로 정보를 얻을 수 있는 시스템의 도입이 점차 확대되는 추세이며, 이것을 위하여 온도, 습도, 가스 등 환경정보를 획득할 수 있는 센서뿐만 아니라 초소형 저전력 복합환경센서 ROIC(Read-Out Integrated Circuit)의 중요성이 증가하고 있다. 또한 휴대폰, 노트북, 스마트폰, 태블랫 PC 등의 모바일 IT 제품들은 빠르게 소형화, 슬림화, 저전력화 되고 있다. 이런 시스템의 요구에 따라 음향부품도 기본적인 음향감지/출력 성능 이외에 크기 및 소모전력이 중요한 기능요소로 크게 부각되고 있으며, 이것을 위하여 소형화, 저가격화가 가능한 MEMS(Microelectromechanical Systems) 음향센서 및 ROIC 개발이 요구되고 있다. 따라서 본고에서는 복합환경센서 ROIC 및 MEMS 마이크로폰 ROIC의 기술동향 등에 대해서 고찰하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.9
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• pp.728-732
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• 2008

This paper presents ion-based micro vibration sensor for the ultra-high frequency vibration detection. Presented sensor uses the motion of anion and cation in an electrolyte. Electrolyte vibration sensors have the high shock survival characteristics and a simple read-out circuit because of the small mass and own charges of ions. Presented sensor measures the induced electric potential by the mechanical-electrical coupling. It consist of electrolyte chamber and detection electrode. Electrolyte chamber was fabricated by PDMS molding. Detection electrode was made of gold evaporation on pyrex glass. Size of electrolyte chamber was designed as $600{\times}600{\times}100um$. Detection electrode had 200nm-thick and 42um-gap. In the experimental study, 5.8M sodium Chloride (NaCl) solution was used as electrolyte in 36nl-chamber. Mechanical vibration was measured from 2kHz to 4MHz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.180-182
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• 2005

비냉각형 적외선 검출 회로 설계 시 공정상 변화에 의해 발생하는 센서의 저항값 변동이 크다. 본 논문에서는 이것을 해결하기 위해 차동적 입력 수신 구조를 이용한 방법을 제시하였다. 볼로미터 타입 비냉각형 적외선 영상 센서 회로는 입사된 적외선 에너지 양에 따라 센서의 저항값이 변하는 특성을 이용하며 그에 따른 전압 또는 전류의 변화를 측정하여 적외선의 파장을 알아내는 방식으로 검출회로 설계 시 가장 큰 문제점인 공정상의 변화 등으로 인한 신호검출 회로의 오동작을 개선하기 위하여 검출회로의 입력단을 차동적으로 받아들이도록 설계하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.3
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• pp.503-510
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• 2006

Readout circuit is to convert signal occurred in a defector into suitable signal for image signal processing. In general, it has to possess functions of impedance matching with perception element, amplification, noise reduction and cell selection. It also should satisfies conditions of low-power, low-noise, linearity, uniformity, dynamic range, excellent frequency-response characteristic, and so on. The technical issues in developing image processing equipment for focal plane way (FPA) can be categorized as follow: First, ultraviolet (UV) my detector material and fine processing technology. Second, ReadOut IC (ROIC) design technology to process electric signal from detector. Last, package technology for hybrid bonding between detector and ROIC. ROIC enables intelligence and multi-function of image equipment. It is a core component for high value added commercialization ultimately. Especially, in development of high-resolution image equipment ROIC, it is necessary that high-integrated and low-power circuit design technology satisfied with design specifications such as detector characteristic, signal dynamic range, readout rate, noise characteristic, ceil pitch, power consumption and so on. In this paper, we implemented a $8\times8$ FPA prototype ROIC for reduction of period and cost. We tested unit block and overall functions of designed $8\times8$ FPA ROIC. Also, we manufactured ROIC control and image boards, and then were able to verify operation of ROIC by confirming detected image from PC's monitor through UART(Universal Asynchronous Receiver Transmitter) communication.

• Korean Journal of Optics and Photonics
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• v.24 no.4
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• pp.176-183
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• 2013

In this paper, we report the design, fabrication and characterization of the 3-Dimensional optical receiver for a Laser Detection And Ranging (LADAR) system. The optical receiver is composed of three parts; $16{\pm}16$ Geiger Mode InGaAs Avalanche Photodiode (APD) array device operated at 1560 nm wavelength, Read Out Integrated Circuit (ROIC) measuring the Time-Of-Flight (TOF) of the return signal reflected from target objects, a package and cooler maintaining the proper operational condition of the detector and control electronics. We can confirm that the LADAR system can detect the signal from a target up to 1.2 km away, and it showed low Dark Count Rate (DCR) of less than 140 kHz, and higher than 28%-Photon Detection Efficiency (PDE). This is considered to be the best performance of the $16{\pm}16$ FPA APD optical receiver for a LADAR system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03a
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• pp.21-21
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• 2010

(Ba,Sr)$TiO_3$ (BST) thin film with a perovskite structure has potential for the practical application in various functional devices such as nonvolatile-memory components, capacitor, gate insulator of thin-film transistors, and electro-optic devices for display. Normally, the BST thin films derived from sol-gel and sputtering are amorphous or partially crystalline when processed below $600^{\circ}C$. For the purpose of integrating BST thin film directly into a Si-based read-out integrated circuit (ROIC), it is necessary to process the BST film below $400^{\circ}C$. The microstructural and electrical properties of low-temperature crystallized BST film were studied. The BST thin films have been fabricated at $350^{\circ}C$ by UV-assisted rapidly thermal annealing (RTA). The BST films are in a single perovskite phase and have well-defined electrical properties such as high dielectric constant, low dielectric loss, low leakage current density, and high breakdown voltage. Photoexcitation of the organics contained in the sol-gel-derived films by high-intensity UV irradiation facilitates elimination of the organics and formation of the single-crystalline phase films at low temperatures. The amorphous BST thin film was transformed to a highly (h00)-oriented perovskite structure by high oxygen pressure processing (HOPP) at as low as $350^{\circ}C$. The dielectric properties of BST film were comparable to (or even better than) those of the conventionally processed BST films prepared by sputtering or post-annealing at temperature above $600^{\circ}C$. When external pressure was applied to the well-known contractive BST system during annealing, the nucleation energy barrier was reduced; correspondingly, the crystallization temperature decreased. The UV-assisted RTA and HOPP, as compatible with existing MOS technology, let the BST films be integrated into radio-frequency circuit and mixed-signal integrated circuit below the critical temperature of $400^{\circ}C$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.1
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• pp.28-35
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• 2007

In this paper, an ultra low voltage SRAM design method based on dual-boosted cell bias technique is described. For each read/write cycle, the wordline and cell power node of the selected SRAM cells are boosted into two different voltage levels. This enhances SNM(Static Noise Margin) to a sufficient amount without an increase of the cell size, even at sub 1-V supply voltage. It also improves the SRAM circuit speed owing to increase of the cell read-out current. The proposed design technique has been demonstrated through 0.8-V, 32K-byte SRAM macro design in a $0.18-{\mu}m$ CMOS technology. Compared to the conventional cell bias technique, the simulation confirms an 135 % enhancement of the cell SNM and a 31 % faster speed at 0.8-V supply voltage. This prototype chip shows an access time of 23 ns and a power dissipation of $125\;{\mu}W/Hz$.

• Journal of Preventive Medicine and Public Health
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• v.6 no.1
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• pp.65-70
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• 1973

The study in the fild of medical instrument has been out of the interest by any of the life scientist in Korea. Especially, the recent developments in the medical electromics are remarkable one. Authors planned this study to ascertain the possibility of setting up the thermister thermometer with available accessories of demestic prouducts including some specific foreign assembly parts. By proper use of the thermister as one of the wheatstone bridge, we could detect tile resistance variations due to the environmental temperature variace. The intensive care for the bridge circuit and compensation scheme was required. The calibration procedure adopted here makes it possible to read the current as the temperature. The temperature range was determined by the examination and construction of the graph of the resistance-temperature variation. The determination of electric current, available ambient-temperature, the reduction of excessive current and self-heating of the thermister were made. Renovation in response-velocity was under taken too. This electronic thermometer was designed and assembled by the circuitry developed in accordance with the maximum availability of domestic products with some foreign-made parts. The result of our experiment showed very stable function and proved to be the most promissing item in the actual application as long as the thermistor thermister is concerned.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.6 s.123
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• pp.477-483
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• 2007

Major noise source in high speed rotating optical disk drives (CD and DVD-ROM) arises due to the high-speed airflow produced from the upper and lower surfaces on the rotating disk. The present paper deals with the experimental approach how to identify the noise source based on the fundamental principles of aeroacoustics and to propose a reduction method of the noise source. The CD-ROM device is composed of disk, window tray, motors at the bottom place and electronic circuit plate also located below the window plate. The window is cut in the tray to read the disk information using the optical device located below the tray and moving linearly from the center of the disk through the end of the disk. All components are possible noise generators. Experimental studies were carried out in the anechoic room with various design modifications, such as tray geometry, window size and hole location on tray, to identify the major aerodynamic noise source and significant reductions of the aerodynamic noise were obtained.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.141-146
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• 2017

In this letter, we propose the use of tunneling field effect transistors (TFET) as a biosensor that detects bio-molecules on the gate oxide. In TFET sensors, the charges of target molecules accumulated at the surface of the gate oxide bend the energy band of p-i-n structure and thus tunneling current varies with the band bending. Sensing parameters of TFET sensors such as threshold voltage ($V_t$) shift and on-current ($I_D$) change are extracted as a function of the charge variation. As a result, it is found that the performances of TFET sensors can surpass those of conventional FET (cFET) based sensors in terms of sensitivity. Furthermore, it is verified that the simultaneous sensing of two different target molecules in a TFET sensor can be performed by using the ambipolar behavior of TFET sensors. Consequently, it is revealed that two different molecules can be sensed simultaneously in a read-out circuit since the multi-sensing is carried out at equivalent current level by the ambipolar behavior.