Image sensors and optical devices
In the typical four-transistor pixel of a CMOS image sensor, which transistor moves the charge from the photodiode to the floating diffusion?
- ATransfer transistor
- BReset transistor
- CSelect transistor
Show answer and explanation
Answer: A. Transfer transistor
A four-transistor pixel consists of transfer, reset, amplifier (source follower) and select transistors. The transfer transistor moves the charge stored in the photodiode to the floating diffusion, and the amplifier transistor outputs its voltage. The reset transistor initializes the floating diffusion, and the select transistor chooses the row to read.