| 摘要 |
PURPOSE:To reduce an offset error and a gain error of an A/D converter by generating a reference input for calibration internally by using a reference voltage and a differential amplifier. CONSTITUTION:The reference voltage Vref is used to compares the absolute value of an analog input voltage from the most significant digit bit successively. The differential amplifier A calculates and amplifies the difference between two inputs e1 and e2 supplied by operating switches S1-S8 selectively, and an output e0 is obtained by operating switches S9-S12 selectively. Sample holding circuits SH1 and SH2 sample and hold the output e0 of the differential amplifier A. A comparator CMP1 compares the output e0 of the differential amplifier A with the reference voltage Vref supplied through switches S15 and S16. A control circuit CONT generates signals for controlling the respective switches while considering the output state eC of the comparator CMP. |
