An Adaptive Event-Driven Condition Generation Circuit for Linear CMOS Image Sensors

This paper presents an analog domain adaptive event-driven condition generation circuit for linear CMOS image sensors. The proposed circuit is implemented by adding operational amplifier and switching capacitor to the traditional single-slope ADC. The gradient voltage is obtained by subtracting the line by line output of pixel array using a subtractor composed of operational amplifier and capacitor. The dynamic comparator shared with single-slope ADC compares adjacent gradient voltages one by one, and the capacitor stores the voltage of the corresponding lines with larger gradient voltage. The voltage corresponding to the maximum gradient is the event driving condition in current detection. This circuit is implemented in UMC 110nm CMOS process with a 3. 3V power supply. The power consumption of the event-driven condition generation circuit is 170$\mu$w, and the layout area is only 330$\mu {\mathrm {m}}\times 10\mu$m, only 10% area increase.