Patent ID: 7554476

Claim:
An analog-to-digital conversion method for converting an analog signal to digital data, the analog-to-digital conversion method comprising the steps of: outputting an upper-bit conversion reference signal used for generating upper bits of digital data which is to be converted from an analog signal; comparing the analog signal with the upper-bit conversion reference signal by using a comparator and obtaining a digital value of the upper bits of the digital data on the basis of a period of time from a set time to the time when a magnitude relation between the analog signal and the upper-bit conversion reference signal is determined to be changed; generating and outputting a lower-bit conversion reference signal used for generating lower bits of the digital data; and comparing the analog signal with the lower-bit conversion reference signal by using the comparator, obtaining a digital value of the lower bits of the digital data on the basis of a period of time from a set time to the time when a magnitude relation between the analog signal and the lower-bit conversion reference signal is determined to be changed, and determining a digital value of digital data converted from the analog signal on the basis of the digital value of the upper bits and the digital value of the lower bits.