Patent ID: 9647020
Date: 2017-05-09
CPC Classifications: H01L

Claim:
1. A light sensing circuit, comprising: a photo transistor having a gate, a drain and a source; a first transistor electrically connecting between the gate and the source of the photo transistor; a first capacitor electrically connecting between the gate and the drain of the photo transistor; a second transistor electrically connecting with the drain of the photo transistor, the first capacitor, and a data signal; a second capacitor electrically connecting between the source of the photo transistor and a ground contact; a third transistor electrically connecting with the photo transistor, the first transistor, and the second capacitor; and a switch adapted to alternatively connect the third transistor with a buffer or a zero signal; wherein a bias situation of the photo transistor is controlled by a negative voltage signal, the first transistor is turned on or off by a first signal, the second transistor is turned on or off by a second signal, and the third transistor is turned on or off by a third signal, so that the buffer outputs a light sensing signal generated by the photo transistor.