Patent ID: 7088279

Claim:
An analog-to-digital conversion method for obtaining digital data of a difference signal component representing a difference between a reference component and a signal component included in an analog signal, wherein, in a first processing iteration, a signal corresponding to one of the reference component and the signal component is compared with a reference signal for conversion into digital data, and concurrently with the comparison, counting is performed in one of a down-count mode and an up-count mode based on a high-speed counter clock composed of pulses having a frequency that is higher than a frequency of a master clock composed of base pulses corresponding to driving pulses for capturing the analog signal subject to processing, holding a count value at a time of completion of the comparison, and in a second processing iteration, the other one of the reference component and the signal component is compared with the reference signal, and concurrently with the comparison, counting is performed in the other one of the down-count mode and the up-count mode based on the high-speed counter clock, holding a count value at a time of completion of the comparison.