An n-bit analog-to-digital converter includes a comparator that compares an analog input voltage with a comparison voltage; and a digital-to-analog converter that generates the comparison voltage in response to a result of the comparator, wherein the analog-to-digital converter outputs n-bit digital data corresponding to the analog input voltage, and wherein the analog-to-digital converter outputs a self-diagnosis result in such a way that the digital-to-analog converter generates a self-diagnosis voltage in response to the n-bit digital data and the comparator compares the analog input voltage with the self-diagnosis voltage.