| 摘要 |
PROBLEM TO BE SOLVED: To enable suppressing an error in a clamp level even if a level shift occurs in a signal from a light-shielding pixel without remarkably increasing a circuit scale. SOLUTION: This circuit is provided with an OB level averaging circuit 42 and an OB average register 43 for calculating and outputting an average value of signals from a plurality of light-shielding pixels of a solid-state image pickup element, and holding the average level; a comparing circuit 46 for comparing the average value held in the OB average register with the level of signals from the light-shielding pixel; and a clamp circuit 6 for adjusting signals from the light-shielding pixels into a predetermined level, on the basis of the average value calculated by the OB level averaging circuit. The average value held in the OB average register is supplied to the OB level averaging circuit instead of signals from the light-shielding pixels in accordance with a result of comparison of the comparing circuit, and thus, an offset quantity can be properly adjusted on the basis of the signals from the light-shielding pixels in as state where a signal having level shift is removed only by adding few circuits. COPYRIGHT: (C)2006,JPO&NCIPI |
