| 摘要 |
PURPOSE: A comparator, an analog-to-digital (A/D) converter, a ramp signal slope compensating circuit, a complementary metal-oxide semiconductor (CMOS) image sensor containing the circuit, and a ramp signal slope compensating method in accordance with the above are provided to prevent the slope ratio of a fine ramp signal to a coarse ramp signal from being distorted due to the slope change of the fine ramp signal and to improve linearity of A/D conversion. CONSTITUTION: An A/D converter (10) includes an amplifier, a comparator (12), a first memory part (16), and a second memory part (18). The amplifier receives a pixel voltage, a reference voltage, a fine ramp voltage, and a coarse ramp voltage. The comparator is equipped with a switch, which is connected between a coarse ramp voltage input terminal receiving coarse ramp voltage input and the amplifier, and a capacitor. One end of the capacitor is connected between the switch and the amplifier, and the other end is connected to a ground voltage. The first memory part stores the most significant bit among 1 least significant bit (LSB) for the coarse ramp voltage. The second memory part stores the least significant bit among 1 LSB for the coarse ramp voltage. [Reference numerals] (12) Comparator; (14) Sink block part; (16) First memory part; (18) Second memory part; (21) Fine ramp generator; (22) Coarse ramp generator; (30) N bit counter |
