Patent ID: 9001249
Filing Date: 2015-04-07
Classification: H04N

Abstract:
1. A solid-state image sensor including a pixel array in which a plurality of pixel units are arranged two-dimensionally, the pixel array including a plurality of column signal lines, and each pixel unit including at least one photoelectric converter and an amplifier transistor which outputs, to the column signal line, a signal corresponding to charges generated in the photoelectric converter, the solid-state image sensor comprising: a cascode current source which supplies a current to the amplifier transistor, the cascode current source including a first transistor and second transistor which are cascode-connected; a first bias circuit which determines a voltage of a first node connected to a gate of the first transistor; a second bias circuit which determines a voltage of a second node connected to a gate of the second transistor; and a first current source which is interposed between a first voltage line and a second voltage line, wherein the amplifier transistor and the cascode current source form a source follower circuit, the first bias circuit determines the voltage of the first node to set a current driving capability of the first transistor when the cascode current source is in an active state, to be equal to a current driving capability of the first transistor when the cascode current source is in an inactive state, the second bias circuit determines the voltage of the second node to set a current driving capability of the second transistor when the cascode current source is in the inactive state, to be smaller than a current driving capability of the second transistor when the cascode current source is in the active state, the first bias circuit includes: