| 摘要 |
PURPOSE:To improve the resolution by determining the number of conversion bits of an A/D converter, the number of bits of a selecting signal, etc., in accordance with specifications of setting a voltage range based on the number of reference voltages to use effectively the low-resolution A/D converter. CONSTITUTION:The A/D converting device is provided with a reference voltage circuit 3 which generates reference voltages having preliminarily determined voltage levels V1-V4, and these reference voltages are selected in a multiplexer 4 in accordance with m-bit selecting signals A1 and A2. A differential voltage between one reference voltage Vr selected by the multiplexer 4 and an input signal voltage Vi is amplified by a differential amplifying circuit 2. The output of the amplifying circuit 2 is converted to m-bit digital data D0-D7 by an A/D converter 1. Further, data D0-D7 from the converter 1 are discriminated by a digital value discriminating circuit 5, and thus, the low-resolution converter 1 is used effectively to output high-resolution digital data D0-D7. |
