| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a solid-state image pickup device including an analog/digital converter (ADC) which can be mounted in a limited space. <P>SOLUTION: A signal of a pixel outputted through a vertical readout line is kept in a node vcm as potential. Capacitors C4 and C40 to C46 are coupled in a capacitive mode to the node vcm where a signal of the pixel is kept. The potential in the node vcm is lowered in a staircase pattern by controlling transistors 54 to 60 to sequentially turn over opposite voltages of the capacitors C4 and C40 to C46. A comparator 35 compares the potential in the node vcm with the potential vdrk of the pixel in a dark state and determines the higher bit of a digital value when the potential in the node vcm becomes lower. Then, conversion is started in the lower bit of the digital value. Accordingly, a constitution of the ADC can be simplified and the ADC can be mounted in the limited space. <P>COPYRIGHT: (C)2011,JPO&INPIT |
