| 摘要 |
PURPOSE:To form an A/D converter with high accuracy by using two 1-bit A/D converters so as to take an excessive output of one A/D converter as an input of the other A/D converter. CONSTITUTION:Switches S11, S14 are closed at a period T1 where a clock CP1 goes to H and the other switch is opened. An input/output terminal of an inverse amplifier 13 has a prescribed value VOFF and a capacitor C2 is charged by a voltage (VIN1-VOFF). Only switches S12, S13 are closed at a period T2 where a clock CP2 goes to H, and a capacitor C1 is charged by a reference voltage VR/2, and an input voltage Vx to the inverse amplifier 13 is expressed as Vx= VR/2-VIN1-VOFF. Either one of switches S15 and S16 is closed at a section T3 where a clock CP3 goes to H. A compared output from the operational amplifier 13 at the said period T2 is transferred to an output side of a D FF17 in the timing of the leading of the clock CP3, and when the compared output goes to L, an output V01 of the inverse amplifier 13 becomes 2VIN1 and when the compared output goes to H, the output V01 becomes 2VIN1-VR. |
