Patent ID: 7154426

Claim:
An analog-digital converter comprising: an analog-digital converter circuit converting an input analog signal into a digital value of a predetermined number of bits; and an input switching circuit switching between a voltage value of said analog signal and a predetermined reference voltage value for input to voltage comparison elements constituting said analog-digital converter circuit, wherein the analog-digital converter circuit is alternately operated in a first period in which it is in an autozero operation mode and a second period in which it compares the voltage value of said analog signal with the predetermined reference voltage value for conversion, and said input switching circuit switches between a mode, in which the voltage value of said analog signal is received in the first period and the reference voltage value is received in the second period, and a mode, in which the reference voltage value is received in the first period and the voltage value of said analog signal is received in the second period, according to a timing schedule of the other constitutes elements.