Design Of A Low-Power CMOS Smoke Detector ASIC Chip

The smoke-detector is widely used in fire-forecast; it plays a very important role in fire identification and alarm in the early stage. As the key part, the smoke-detector chip is used to control the detecting system by sampling and processing the sensor signals. This paper has designed an ASIC smoke-detector chip based on the photoelectrical sensor. By distinguishing the smoke conditions, the fire danger can be discovered and alarmed in an early stage. Also the chip can make out the false cases to avoid mis-alarm, so as to build a reliable safe monitoring system. This chip is a analog-digital mixed chip, fabricated in the CMOS high-voltage process, it has the advantages of high precision, low-power and high testability.Based on study of the photoelectrical sensor system, this paper has designed a low-power and testable ASIC chip used for smoke detection. By analyzing the system functionality and application environment, the design goal is brought forward, and the system architecture design is finished to make the manageable functional parts clear, and also the low-power and testability design method is schemed out. The circuit design is preceded based on the research, and the paper mainly analyzes the design method, circuit implementation, and the simulation results of the low-power opt. amplifier, the comparator, the bandgap reference, the strobe pseudo-ground circuit, etc. After the mixed-signal system simulation proved the functionality of the circuit, the layout is designed using the chartered 0.35μm high-voltage process and the chip is taped out. The test result showed that the system works as it is expected, and the entire functionality and design goal is fully reached. The average working current is only 7μA, which means that the chip has reached the low-power design goal.The creativity of this paper is presented by its low-power design. A sleep mode is designed in the system to save power under certain conditions. Also an innovative strobe pseudo-ground signal circuit is designed to reduce the static current so as to control the power consumption and improve the lifespan of the battery.