A/D CONVERTER, IMAGE SENSOR DEVICE, AND METHOD OF GENERATING DIGITAL SIGNAL FROM ANALOG SIGNAL
The objective of the present invention is to attain an A/D converter that executes integration type A/D conversion, and cyclic type A/D conversion for the residual analog signal thereof, with a single-ended configuration. According to this A/D converter, a first A/D conversion operation for executing the integrating type A/D conversion, and a second A/D conversion operation for executing the cyclic type A/D conversion are attained by controlling the operation procedure of the same circuit configuration. Further, since, in the first A/D conversion operation, the capacity of a capacitor to be used for integrating the output signal is larger than the capacity of a capacitor to be used for storing an input analog signal and a reference voltage, an analog signal to be inputted for the integration type A/D conversion is attenuated according to the capacity ratio of the capacitors, before being sampled and integrated. Since the voltage range of the analog signal to be outputted in the integration type A/D conversion will become smaller according to the capacity ratio of the capacitors, an A/D converter can be configured with a single-ended configuration.