• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.569-572
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• 2014

본 논문에서는 MEMS 용량형 센서를 위한 CMOS 스위치드-커패시터 인터페이스 회로를 설계하였다. 설계된 회로는 커패시턴스-전압 변환기(CVC), 2차 스위치드 커패시터 ${\Sigma}{\Delta}$ 변조기 및 비교기로 구성되어있다. 또한 일정한 바이어스를 공급해주는 바이어스 회로를 추가하였다. 전체적인 회로의 저주파 잡음과 오프셋을 감소시키기 위하여 Correlated-Double-Sampling(CDS) 기법과 Chopper-Stabilization(CHS) 기법을 적용하였다. 설계 결과 CVC는 20.53mV/fF의 민감도와 0.036%의 비선형성특성을 보였으며, ${\Sigma}{\Delta}$ 변조기는 입력전압 진폭이 100mV가 증가할 때, 출력의 듀티 싸이클은 약 5%씩 증가하였다. 전체회로의 선형성 에러는 0.23% 이하이며, 전류소모는 0.73mA이다. 제안된 회로는 0.35um CMOS 공정을 이용하여 설계되었으며, 입력전압은 3.3V이다. 설계된 칩의 크기는 패드를 포함하여 $1117um{\times}983um$ 이다.

• 한국전기전자재료학회논문지
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• 제27권9호
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• pp.566-570
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• 2014

Electrode pattern effects on the capacitive humidity sensor were investigated. The fabrication of the capacitive humidity sensor was formed with three steps. The bottom electrode was formed on the silicon substrate with Pt/Ti thin layer by using shadow mask and e-beam evaporator. The photo sensitive polyimide was formed on the bottom electrode by using photolithography process as a humidity sensitive thin film. The upper electrode was formed on the polyimide thin film with Pt/Ti thin layer by using e-beam evaporator and lift-off method. Three electrode patterns, such as circle, square, and triangle pattern, were used and changed the sizes to investigate the effects. The capacitances of the sensors were decreased 622 to 584 pF with the area decreament of patterns 250,000 to $196,250{\mu}m^2$. From these results, a capacitive humidity sensor with photo sensitive polyimide is expected to be applied to a high sensitive humidity sensor.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.910-912
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• 2015

본 논문에서는 중장비나 댐의 수문 등의 적용된 유압 실린더의 변위(stroke)를 검출하여 유압 실린더의 정밀제어 또는 자동화를 위한 정전용량 센서(Capacitive Sensor) 및 변위 검출 시스템을 설계하였다. 기존 실린더의 변위 검출 방식인 코일을 이용한 자기장 센서, LVDT 센서 등은 높은 정확도에 비해 충격 및 진동 완화 또는 센서 보호 하우징(Housing) 등 부수적인 설비에 따른 높은 비용, 큰 부피와 같은 문제가 있다. 따라서 이러한 개선하기 위해 유압 실린더 내의 직접 적용되어 실린더의 변위 검출이 가능한 정전용량 센서를 설계하였으며, 설계한 정전용량 센서를 통하여 실린더의 변위에 따른 커패시턴스 값을 검출하여 실린더 위치 측정이 가능한 시스템을 설계 및 검증 하였다.

• 센서학회지
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• 제16권2호
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• pp.97-103
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• 2007

Crystallized carbon nitride film that has many stable physical and/or chemical properties has been expected potentially by a new electrical material. However, one of the most significant problems degrading the quality of carbon nitride films is an existence of N-H and C-H bonds from the deposition environment. The possibility of these reactions with hydroxyl group in carbon nitride films, caused by a hydrogen attack, was suggested and proved in our previous reports that this undesired effect could be applied for fabricating micro-humidity sensors. In this study, MIS capacitor and MIM capacitor with $5{\mu}m{\times}5{\mu}m$ meshes were fabricated. As an insulator, carbon nitride film was deposited on a $Si_{3}N_{4}/SiO_{2}/Si$ substrate using reactive magnetron sputtering system, and its dielectric constant, C-V characteristics and humidity sensing properties were investigated. The fabricated humidity sensors showed a linearity in the humidity range of 0 %RH to 80 %RH. These results reveal that MIS and MIM $CN_{X}$ capacitive humidity sensors can be used for Si based micro-humidity sensors.

• 한국소음진동공학회논문집
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• 제20권5호
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• pp.437-443
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• 2010

SAW device is widely used as band pass filters, chemical or physical sensors, and actuators. In this paper, we propose the capacitive gap measurement system with high precision using SAW device. The research process is mainly composed of theoretical and experimental part. In the theoretical part, equivalent circuit model was used to predict the SAW response by the change of load impedance. In the experimental part, commercialized capacitor was used to see the SAW response by the change of load capacitance to check the feasibility as a sensor unit. After that, experimental setup to measure and adjust the gap was made and the SAW response by the change of gap which caused the capacitance change was measured. Finally, resolution and stroke was decided compared with the signal change and basic measurement noise level.

• 센서학회지
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• 제24권3호
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• pp.208-213
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• 2015

The purpose of this study is to optimize the design of a capacitive pressure sensor element using the simulation of electrical characteristics. The simulation of the ceramic sensor diaphragm ($Al_2O_3$) was performed by permitting pressure to change the curvature of the diaphragm. The pressure capacitance ($C_P$) was increased from 19.63 pF to 15.26 pF by applying pressure because the distance between the electrodes has been changed from $30{\mu}m$ to $15{\mu}m$. When the thickness of the diaphragm was changed to 0.46~0.52 mm, a larger capacitance change showed in accordance with the reduced thickness, which means an increase of sensitivity. However, considering the viewpoint of the signal linearity, it was selected for the optimum thickness of the diaphragm to 0.50 mm. The designed sensor element based on simulated results was tested to measure the output characteristics. Comparing of simulated and measured results, there was a margin of error of approximately 2%.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.964-967
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• 2009

A new hybrid-type touch screen panel (TSP) has been developed based on a-Si:H TFT which can detect the change of both $C_{LC}$ and photo-current. This TSP can detect the difference of $C_{LC}$ between touch and no-touch states in unfavorable conditions such as dark ambient light and shadows. The hybrid TSP sensor consists of a detection area which includes one TFT for photo sensing and two TFTs for amplification. Compared to a single internal capacitive TSP or an optical sensing TSP, this new proposed hybrid-type TSP enables larger sensing margin due to embedding of both optical and capacitive sensors.

• 전자공학회논문지A
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• 제30A권7호
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• pp.82-88
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• 1993

This paper describes fabrication of relative type capacitive pressure sensor to be in great demand for many fields. The fabricated sensor consists of two parts` a sensing diaphragm and a pyrox glass cover. The sensor size is 4.5${\times}3.4mm$^{2})$ and 400$\mu$m thick. To improve the nonlinearity, this sensor is designed a rectangular silicon diaphragm with a center boss structure, and in order to improve the temperature characteristics of the sensor in a packaging process, the sensing element is mounted on the pyrex glass support. Some suggestions toward the design and fabrication of improved sensors have been presented. The zero pressure capacitance, Co of sensor is 26.57pF, and the change of capacitance, ${\Delta}$C is 1.55pF from 0Kgf/Cm$^{2}$ to 1Kgf/Cm$^{2}$ at room temperature. The nonlinearity of the sensor output with center boss diaphragm is 1.29%F.S., and thermal zero shift and thermal sensitivity shift is less than 1.43%F.S./$^{\circ}C$and 0.14% F.S./$^{\circ}C$, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.335-338
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• 2005

Starting with the development of environmentally friendly electric controlled engine, sensors have played an increasing role in automotive technology. Electric power steering (EPS) systems are more and more replacing hydraulic systems. To improve fuel economy, the power assistance is provided by an electric drive. In this paper, development of a unique torque sensor for EPS is introduced. A capacitive type torque sensor is concluded to be suitable for EPS because its output is accurate, linear and robust against the variance of temperature, and patents have not applied so much.

• Tribology and Lubricants
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• 제10권4호
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• pp.27-32
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• 1994

The capacitive type transducers measure the displacement of rotating shaft using the voltage difference which is formed between the sensor plates and rotor so that the measured signal is not affected by the magnetic field generated by the magnetic bearing. In this paper, the capacitive transducers are embedded inside of the magnetic bearing. In order to verify the support characteristics of the capacitance sensor-magnetic bearing system, we experimented and analyzed the magnetic bearing-rotating shaft system up to 12,000 rpm. The magnetic bearing system proposed in this paper, successfully supports the rotating shaft and we can remain the maximum displacement below $5 \mu m$ at 12,000 rpm.