Two Transistor Current Mode Active Pixel Sensor

A novel current mode active pixel sensor for high resolution imaging is presented. The photo pixel is composed of a photodiode and two transistors: reset and transconductance amplifier transistor. The switch transistor is moved outside the pixel, allowing for lower pixel pitch and increased linearity of the output photocurrent. The increased linearity of the image sensor has greatly reduced spatial variations across the image after correlated double sampling and the column fix pattern noise is 0.35% of the saturated current. A discussion on theoretical temporal noise limitations of this design is also presented.