Low voltage time based CMOS active pixel sensor

This paper proposes a low voltage time based CMOS active pixel sensor (TBAPS). The TBAPS applies the ramp signal to the pixel and performs the charge-to-time conversion in the pixel. The readout circuit detects the moment of event rather than reading the voltage signal. The proposed TBAPS improves the detection of the low illumination signal compared with the conventional TBAPS. The simulation results show that the proposed scheme provides 1 V signal range with a 1.5 V power supply voltage and 22% fill factor of 2.2 mum pixel pitch in a 0.13 mum CMOS technology.