In a rear-surface irradiation type image sensor that is becoming mainstream in recent years, it is possible to increase the number of vertical signal lines per pixel column. Along with this, also architecture such as high-speed signal readout from a pixel unit and signal addition using the vertical signal line is in development.
On the other hand, in a circuit including a plurality of vertical signal lines per pixel column, the image quality may be degraded due to the difference between voltage states of the vertical signal lines or individual discrepancies thereof. In Patent Document 1, it is proposed that in a circuit including one vertical signal line per pixel column, the degradation of the image quality is suppressed by fixing the potential to midpoint potential in order to suppress sub-wobble noise.    Patent Document 1: Japanese Patent Application Laid-open No. 2005-311932