| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit and a method for calibration, which can correct the deviation if any in convergence value of a circuit from a desired reference value due to an offset and output a desired optical black level. SOLUTION: A circuit for calibration of optical black level is provide with: an optical black level circuit 5 for detecting the optical black level; a 1st subtracting circuit 11 which receives the output signal of the optical black level detecting circuit 5 and corrects an error of the optical black level from a desired value; and a 2nd subtracting circuit 10 which receives the output signal of the optical black level detecting circuit 5 and detects an error value of the optical black level from a desired value. In the circuit for calibration of optical black level, in a period wherein the error value of the optical black level from the desired value is detected, zero is inputted to the 1st subtracting circuit 11 before latching with an externally supplied latch signal and the error value of the optical black level from the desired value by the 2nd subtracting circuit 10 is supplied to the 1st subtracting circuit 11 after the latching. COPYRIGHT: (C)2005,JPO&NCIPI
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