A low-cost CMOS intelligent light-sensing chip for environment light-sensing applications

In this paper, an intelligent light-sensing system is newly discussed and it consists of a proposed CMOS light-sensing chip, a dc to dc converter and an artificial light. Another innovation is that the pulse width modulation circuit is newly proposed and has a widely adjustable duty cycle from 100% to 7.24%. The proposed technique is attractive due to the fact that the proposed light-sensing system is low-cost and easier to be implemented. The chip area is 1.0529 × 0.7086 mm². When the voltage comparing circuit is not used, the proposed chip can also be utilized as a light to duty cycle converter. The simulated lightness (photocurrent) is from 0.4 nA to 40 nA and the corresponding duty cycle is from 11.7% to 100%. The proposed chip is suitable for automatic environment lighting-sensing applications.