| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a delta-sigma type A/D conversion device that can perform high accuracy conversion even if an input voltage must be A/D-converted within a fixed period.SOLUTION: An input voltage Vin is passed through loop filters 13 and 14 and then quantized in a quantizer 7. The loop filter 14 includes an operational amplifier 15 for generating an output voltage thereof, a capacitor Cs for sampling the input voltage Vin, a capacitor Cf for integrating the voltage sampled by the capacitor Cs, and a plurality of path changeover switches S1-S7. A control circuit controls on/off of the switches S1-S7 to discharge the capacitors Cs and Cf, and then repeats sampling and integrating operations of the loop filter 14 more than once. Finally, the connection state of the capacitor Cs and the capacitor Cf is reversed from the integrating operations and a converting switch S8 is turned on, so that an A/D converter 12 A/D-converts the output voltage of the loop filter 14.</p> |
