An auto-balancing capacitance-to-pulse-width converter for capacitive sensors

A novel auto-balancing capacitance-to-pulse- width converter (CPC) that uses sinusoidal excitation, and operates in a closed-loop configuration, is presented in this paper. Unlike most of the existing CPCs, the proposed interface circuit is compatible with both single-element and differential capacitive sensors. In addition, it provides a pulse-width modulated (PWM) signal which can easily be digitized using a counter. From this PWM signal, a ratio output is derived when a single-element sensor is interfaced, and a ratiometric output is obtained for a differential sensor.The authors would like to thank the Department of Science and Technology (DST), Govt. of India, for its financial assistance (Grant Number SERB/F/4573/2016-17) in carrying out the research activities presented in this paper.Postprint (published version

미세 입자 검출을 위한 저잡음 광학 센서 인터페이스

학위논문 (박사)-- 서울대학교 대학원 : 공과대학 전기·정보공학부, 2018. 8. 김수환.In this study, I propose a low-noise sensor interface for optical particulate matter (PM) detectors. The particles are classified as particulate matter 10 (PM10) ( CONTENTS 4 LIST OF FIGURES 6 LIST OF TABLES 9 CHAPTER 1 INTRODUCTION 1 1.1 PARTICULATE MATTER 1 1.2 PARTICULATE MATTER DETECTOR 3 1.2.1 CAPACITIVE SENSORS 3 1.2.2 OPTICAL SENSORS 6 1.3 THESIS ORGANIZATION 11 CHAPTER 2 ARCHITECTURE AND DESIGN CONSIDERATIONS OF THE OPTICAL PARTICULATE MATTER DETECTOR 12 2.1 INTRODUCTION 12 2.2 ANALOG FRONT-END CIRCUIT 15 2.2.1 TRANSIMPEDANCE AMPLIFIER 15 2.2.2 DC OFFSET CALIBRATION 19 2.2.3 GAIN AND FILTER STAGES 23 2.2.4 ANALOG-TO-DIGITAL CONVERTER 25 2.2.5 AVERAGE POWER CONTROL 29 2.3 DIGITAL BACK-END LOGIC 31 CHAPTER 3 CIRCUIT IMPLEMENTATION OF THE PROPOSED OPTICAL PARTICULATE MATTER DETECTOR 34 3.1 SENSOR BLOCK DIAGRAM 34 3.2 ANALOG FRONT-END CIRCUIT 41 3.2.1 DC OFFSET CALIBRATION CIRCUIT 44 3.2.2 ON-CHIP TEMPERATURE SENSOR CIRCUIT 49 3.3 DIGITAL BACK-END LOGIC 52 3.4 POWER MANAGEMENT CIRCUIT 58 3.4.1 UNDERVOLTAGE-LOCKOUT CIRCUIT 58 3.4.2 BANDGAP REFERENCE 61 3.4.3 OSCILLATOR 62 CHAPTER 4 EXPERIMENTAL RESULTS 64 4.1 DIE MICROGRAPH AND MODULE 64 4.2 MEASUREMENT SETUP 67 4.3 MEASUREMENT RESULTS 69 CHAPTER 5 CONCLUSION 77 BIBLIOGRAPHY 79 한글 초록 82Docto

Induction Motors

AC motors play a major role in modern industrial applications. Squirrel-cage induction motors (SCIMs) are probably the most frequently used when compared to other AC motors because of their low cost, ruggedness, and low maintenance. The material presented in this book is organized into four sections, covering the applications and structural properties of induction motors (IMs), fault detection and diagnostics, control strategies, and the more recently developed topology based on the multiphase (more than three phases) induction motors. This material should be of specific interest to engineers and researchers who are engaged in the modeling, design, and implementation of control algorithms applied to induction motors and, more generally, to readers broadly interested in nonlinear control, health condition monitoring, and fault diagnosis

Capacitive Touch Panel with Low Sensitivity to Water Drop employing Mutual-coupling Electrical Field Shaping Technique

This paper proposes a novel method to reduce the water interference on the touch panel based on mutual-capacitance sensing in human finger detection. As the height of a finger (height >10 mm) is far larger than that of a water-drop (height 10 mm) and low in the low-height space (height <1 mm), the sensing cell can be designed to distinguish the finger from the water-drop. To achieve this density distribution of the electrical field, the mutual-coupling electrical field shaping (MEFS) technique is employed to build the sensing cell. The drawback of the MEFS sensing cell is large parasitic capacitance, which can be overcome by a readout IC with low sensitivity to parasitic capacitance. Experiments show that the output of the IC with the MEFS sensing cell is 1.11 V when the sensing cell is touched by the water-drop and 1.23 V when the sensing cell is touched by the finger, respectively. In contrast, the output of the IC with the traditional sensing cell is 1.32 and 1.33 V when the sensing cell is touched by the water-drop and the finger, respectively. This demonstrates that the MEFS sensing cell can better distinguish the finger from the water-drop than the traditional sensing cell does.National Research Foundation (NRF)Accepted versionThis work was supported in part by the National Natural Science Foundation of China (NSFC) under Grant 61771363, in part by the China Scholarship Council (CSC) under Grant 201706960042, and in part by the National Research Foundation of Singapore under Grant NRF-CRP11-2012-01