Patent ID: 7439889

Claim:
An AD converter, comprising: a sampling section for sampling an input signal at each cycle Ts; an AD conversion section for sampling the input signal at the same time as the sampling section and performing AD conversion of the sampled input signal; a DA conversion section for performing DA conversion of an output of the AD conversion section; and a loop filter for integrating a difference obtained by subtracting an output of the DA conversion section from an output of the sampling section so as to output the integrated difference to the AD conversion section, wherein the sampling section includes a plurality of sampling circuits disposed parallel to each other, the plurality of sampling circuits respectively operate at timings different from each other, and each of the sampling circuits keeps the sampled input signal from being transferred to the loop filter for ½ or more of the cycle Ts just after completion of the sampling of the input signal, during which the AD conversion section samples the input signal so as to cancel out the input signal component in the input signal to the loop filter.