A successive approximation type A/D conversion circuit comprising a capacitor type DAC and configured to convert an analog input signal into a digital output signal, the capacitor type DAC including:
- a capacitor array including a plurality of capacitors;
- and
- a switch array configured to selectively apply a first reference voltage, a second reference voltage higher than the first reference voltage, or the analog input signal individually to a first end of each of the plurality of capacitors, one or more capacitors among the plurality of capacitors belonging to a first type capacitor, the other capacitors among the plurality of capacitors belonging to a second type capacitor, a second end of the first type capacitor being connected to a first signal wiring, and a second end of the second type capacitor being connected to a second signal wiring,
- wherein the successive approximation type A/D conversion circuit further comprises:
- a first reference switch provided between the first signal wiring and a first reference wiring to which the first reference voltage is applied;
- a second reference switch provided between the second signal wiring and a second reference wiring to which the second reference voltage is applied;
- a connection switch provided between a third signal wiring and each of the first signal wiring and the second signal wiring;
- a comparator;
- and
- a control circuit configured to control states of the switch array, the first reference switch, the second reference switch, and the connection switch,
- wherein during a sampling period, the control circuit applies the first reference voltage to the first signal wiring while applying the second reference voltage to the second signal wiring by controlling the first reference switch and the second reference switch to be on, and controls the connection switch to be off,
- wherein during a successive approximation period after the sampling period, the control circuit electrically connects each of the first signal wiring and the second signal wiring to the third signal wiring by controlling the first reference switch and the second reference switch to be off and controlling the connection switch to be on,
- wherein during the successive approximation period, the comparator compares a first comparison voltage applied to the third signal wiring with a predetermined second comparison voltage to generate a comparison result signal, and
- wherein the control circuit determines a value of the digital output signal based on the comparison result signal while applying the analog input signal to a plurality of first ends of the plurality of capacitors via state control of the switch array during the sampling period and applying the first reference voltage or the second reference voltage individually to the plurality of first ends via state control of the switch array during the successive approximation period.