| 摘要 |
PROBLEM TO BE SOLVED: To improve the precision of an oversampling-type A/D converter. SOLUTION: The A/D converter is configured by separating quantization and sampling. Therefore, the converter has aΣ-Δmodulator equipped with an integrater 10 and a quantizer 20 using a Josephson junction, and a high time resolution sampling device 40. The quantizer 20 outputs pulses regardless of a clock signal when an input exceeds a threshold. As a result, an analog input is modulated to a pulse density modulated wave by theΣ-Δmodulator regardless of the clock signal. This pulse density modulated wave is input to the first to the fourth DFFs (D-flip-flops) 41 to 44 of the high time resolution sampling device 40. As the DFFs 41 to 44 are supplied with the first to the fourth clock signals, respectively, which are delayed by a shorter time than a cycle of the clock signal, sampling is performed with a high time precision by the DFFs 41 to 44. COPYRIGHT: (C)2004,JPO&NCIPI
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