Photodiode-Type 4-Tr Active Pixel Sensor Cells with Seamless Switching between Linear and Logarithmic Responses

Abstract

A novel operation scheme that creates combined linear-logarithmic responses in photodiode (PD)-type 4-transistors active pixel sensor (APS) cells is described. we found that our APS cells can be operated with seamlessly combined linear-logarithmic responses by setting the reset transistor in weak inversion through properly selected bias voltages.