Analog-digital conversion circuit, sensor apparatus, cellular phone, and digital camera

An analog-digital conversion circuit comprising:

• a first capacitor;
• a digital conversion section that converts an amount of electric charge stored in the first capacitor into a digital signal;
• and
• a charge and discharge control section that controls charge and discharge of the first capacitor,
• the charge and discharge control section putting, into the first capacitor, an electric charge corresponding to an electric current inputted to the analog-digital conversion circuit during a first period,
• the charge and discharge control section causing an electric charge corresponding to an electric current inputted to the analog-digital conversion circuit during a second period that follows the first period to be discharged from the first capacitor,
• the charge and discharge control section performs more than once a charge and discharge cycle including (i) charging the first capacitor during the first period and (ii) discharging the first capacitor during the second period,
• during an analog-digital conversion period that comes after the end of the charge and discharge control carried out by the charge and discharge control section, the digital conversion section converting an amount of electric charge stored in the first capacitor at the end of the charge and discharge control into a digital signal.