Linear-Logarithmic Two-Transistor Active Pixel Sensor with Variable Dynamic Range

摘要

In this paper, we present a linear-logarithmic two-transistor active pixel sensor (APS) with variable dynamic range. The proposed APS is composed of two-transistor with a shared reset transistor for shrink pixel size and wide dynamic range (WDR) characteristics. The select transistor can be eliminated by changing the pulse signal through the drain node of the source follower. The proposed APS uses a gate/body tied metal oxide field-effect transistor type photodetector (GBT-PD) for high sensitivity. Also, we applied the negative feedback structure, which offers significant advantages and allows obtaining WDR without complex circuitry. The sensitivity of the proposed APS is 8.23 V/lux•s in the linear region and 0.32 mV/lux•s in the logarithmic region, while its combined dynamic range reaches 112.1 dB. The sensor was fabricated by using the 0.18 µm 1-poly 6-metal CMOS process and its performance was evaluated.