摘要 |
The invention relates to an image pick up device ( 401 ) with pixels arranged in rows and columns. Every pixel ( 301 ) comprises a photosensitive element ( 302 ), a floating diffusion ( 304 ), a transfer transistor ( 303 ), an amplifying transistor ( 305 ) having its control electrode connected to the floating diffusion ( 304 ), and a reset transistor ( 306 ). An external node ( 310 ) is coupled to a selection switch via a row selection bus ( 406 ). The selection switch ( 411 ) provides either a first bias voltage, generated by a first voltage source ( 409 ), or a second bias voltage, generated by a second volt age source ( 410 ), to the row selection bus ( 406 ). Applying the first bias voltage and simultaneously turning on the reset transistor ( 306 ) programs the floating diffusion ( 304 ) to the first bias voltage which biases the amplifying transistor ( 305 ) in an on-mode, thereby selecting the pixel ( 301 ). Likewise, applying the second bias voltage biases, the amplifying transistor ( 305 ) in an off-mode, thereby deselecting the pixel ( 301 ). This way of selecting and deselecting pixels avoids the need for a separate selection transistor in every pixel, thereby increasing the fill factor of the pixels. This approach is especially useful for image pick up devices applying correlated double sampling (CDS). |