Photoelectric conversion apparatus, control method thereof, imaging apparatus, and imaging system

A photoelectric conversion apparatus comprising:

• a pixel array in which a plurality of pixels are arranged to form rows and columns, each pixel including:
• a photoelectric conversion unit,
• a charge-voltage converter configured to convert electrical charges generated in the photoelectric conversion unit into a voltage
• a source follower transistor configured to output a signal corresponding to the voltage converted by the charge-voltage converter and to output the signal to a vertical output line, and
• a reset unit configured to reset the charge-voltage converter;
• and
• a clip unit configured to clip a voltage of the vertical output line, wherein the clip unit includes:
• a common gate amplifier including a first conductivity-type MOS transistor that includes a drain connected to a current source load, a source connected to the vertical output line, and a gate to which a predetermined voltage is supplied, and
• a common source amplifier including a second conductivity-type MOS transistor that includes a gate connected to the drain of the first conductivity-type MOS transistor, a drain connected to the source of the first conductivity-type MOS transistor and the vertical output line, and a source connected to a power supply.