Photovoltaic Sensors: Logarithmic Pixel Technology

This lecture discusses the principles and applications of logarithmic sensors, specifically focusing on a photovoltaic camera utilizing a logarithmic sensor. The instructor introduces the standard 3-transistor logarithmic sensor and proposes an advanced 4-transistor pixel design that incorporates a photovoltaic cell as a sensor. The operation of the solar cell is explained, highlighting how illumination affects the barrier and results in a logarithmic voltage output. The design features a reset mechanism to apply zero bias voltage to the solar cell, allowing for negative voltage output under illumination, which integrates light intensity. The lecture also covers the role of PMOS transistors in the pixel design, including a source follower that acts as a charge-to-voltage converter. The potential for integrating this technology on a single chip for visible light applications is discussed, along with adaptations for near-infrared light using indium-gallium arsenide photodiodes. The lecture emphasizes the innovative aspects of the Magic™ ROIC and its applications in imaging solutions.