| 摘要 |
PROBLEM TO BE SOLVED: To provide an A-D converter which can carry out A-D conversion after converting an input signal other than a voltage to a voltage signal.SOLUTION: A control circuit 8 connects an initialized capacitor CG between input and output terminals of an operational amplifier 9, and then a charging signal Sin is applied in a state that a switch S12 is opened, and the charge setting of the capacitor CG is carried out. Thus, a conversion voltage corresponding to the charging signal Sin is outputted from the operational amplifier 9. Afterward, the control circuit sets charges which correspond to the conversion voltages in capacitors CF, CS10, CS11, and reallocates the charges among the capacitors by connecting non-common side electrodes of the capacitors CS10, CS11 to one of a plurality of reference voltage lines in accordance with a conversion result of an A-D conversion circuit 7 in a state that the capacitor CF is connected between the input and output terminals of the operational amplifier. The control circuit thereafter performs, a number of times, charge setting, initialization, and subsequent charge reallocation in accordance with a residual voltage outputted from the operational amplifier 9. |
