Correlated double sampling circuit and CMOS image sensor including the same

A correlated double sampling circuit for processing signals output from a pixel section where solid-state image sensing devices are arranged like a matrix, the circuit comprising:

• a first capacitor for sampling and holding reset level signals corresponding to noise produced by resetting the pixel section, a first terminal of the first capacitor being connected to an output terminal of the pixel section at sampling time, and a second terminal of the first capacitor being connected to predetermined power supply for generating predetermined reference potential for sampling;
• and
• a second capacitor connected in parallel with the first capacitor and connected via a connection switch for sampling and a connection switch for reading located in parallel with the connection switch for sampling to the second terminal of the first capacitor and the predetermined power supply for sampling and holding detected signals obtained by a photoelectric conversion in the pixel section,
• wherein:
• the connection switch for sampling connects the second capacitor to the first capacitor and the predetermined power supply while the second capacitor samples the detected signals;
• and
• the connection switch for reading connects the second capacitor to the first capacitor and the predetermined power supply while output signals according to a difference between the detected signals and the reset level signals obtained from electric charges sampled and held in the second capacitor and the first capacitor are read.

A CMOS image sensor comprising:

• a pixel section where unit pixels including a photodiode and transistors are arranged like a matrix;
• a scanning circuit for scanning the pixels;
• and
• a correlated double sampling circuit for processing signals output from the pixel section, the circuit including:
• a first capacitor for sampling and holding reset level signals corresponding to noise produced by resetting the pixel section,
• a second capacitor for sampling and holding detected signals obtained by a photoelectric conversion in the pixel section,
• a connection switch for sampling for controlling connection between predetermined power supply which generates arbitrary potential to sample the detected signals with the arbitrary potential as reference and the second capacitor, and
• a connection switch for reading for controlling reading of output signals according to a difference between the detected signals and the reset level signals obtained from electric charges sampled and held in the second capacitor and the first capacitor.