| 主权项 |
1. An A/D conversion device comprising:
a level shifter circuit configured to level-shift an analog voltage of an input voltage signal to generate a conversion signal; an A/D converter configured to A/D-convert a voltage of said conversion signal supplied from said level shifter circuit into a digital value, wherein said level shifter circuit subtracts an instantaneous voltage value of said input voltage signal from a reference voltage so as to output a signal value as said conversion signal; and a reference voltage setting part configured so as to divide a voltage range in which a voltage value of the input voltage range varies into plural voltage regions each having a width which is equal to or less than an input range of said A/D converter, and to select, from said plural voltage regions, an instantaneous voltage region including said instantaneous voltage value of said input voltage signal, and to set, as said reference voltage, a maximal voltage value in said instantaneous voltage region selected. |
