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A Low-Power Large-Dynamic-Range Time-Domain Interface Circuit for Resistive Gas Sensors

A Low-Power Large-Dynamic-Range Time-Domain Interface Circuit for Resistive Gas Sensors
Translated Title
저항식 가스센서 측정을 위한 저전력 넓은 동적범위를 갖는 시간 도 메인 인터페이스 회로 설계
Choi, Bong Sik
DGIST Authors
Choi, Bong Sik; Lee, Jung Hyup; Je, Min Kyu
Lee, Jung Hyup
Je, Min Kyu
Issue Date
Available Date
Degree Date
2017. 2
Resistance read-out systemTime domainScalable inverterSwing-boostPVT variation insensitive크기 조절 반전기시간 도메인저항 측정용 회로
This thesis is looks into a low-power large-dynamic-range time-domain interface circuit for resistive gas sensors. Recently, as the pollution of the air has attracted attention as a social problem, the regulation of the harmful gas of the government is becoming more and more subdivided. Gas sensor measurement systems are required to satisfy various gas sensor measurement ranges in order to satisfy the subdivided values according to the gas. One of the features of the thesis is that an inverter, which is able to change size, was applied to proceed with a low-power method and a signal was processed in time domain to possess wide measurement range. Another feature of the thesis is that by using swing-boosting method, this circuit has an advantage on noise characteristic. The size of the inverter is controlled by the size of the oscillator and the size of the inverter is controlled according to the operating frequency. The other feature is that it enables to adjust resolution in accordance with related purpose, using frequency divider. Besides, it enables to maintain optimal performance even in any resistance value through scalable method and frequency divider applied resolution adjustment. It is characterized by the ability to maintain optimal performance at any resistance value through resolution control using the size adjustment method and frequency divider. Hynix/Dongbu HiTek 0.18 process is applied through IDEC MPW. The circuit size is 0.35〖mm〗^2, and power consumption is 150uW in 1V operation voltage. ⓒ 2017 DGIST
Table Of Contents
1.Introduction 1 -- 1.1Motivation 1 -- 1.2Gas sensing principle and resistance ranges 2 -- 1.3Resistance read-out methods 4 -- 1.4Proposed system and target specification 7 -- 1.5Oscillator 8 -- 2.Background information: Frequency stability 12 -- 2.1Frequency domain 12 -- 2.2Time domain definitions 14 -- 2.3Power-law noise models 15 -- 2.4Wiener-Khinchine theorem 16 -- 2.5Phase noise for designing oscillator 17 -- 2.6FOM 17 -- 3.Noise analysis 19 -- 3.1Input referred noise of inverter 19 -- 3.2Noise contribution to phase noise 21 -- 4.System structure & Operation principle 31 -- 4.1Structure block diagram 31 -- 4.2Details of each blocks 32 -- 4.3Measurement operation and equations 37 -- 4.4Sensing resolution and Trade-off with measurement time 40 -- 5.Schematic design and Layout 41 -- 5.1Schematic design 41 -- 5.2Layout 45 -- 6.Simulation results 48 -- 6.1Post layout simulation: Oscillator 48 -- 6.2Post layout simulation: Programmable frequency converter and Frequency-to-Digital converter 49 -- 6.3Size optimization of scalable inverter based oscillator 50 -- 7.Conclusion & Future work 51 -- 8.Reference 53
Information and Communication Engineering
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