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

Abstract

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