Complete testing of an analog-to-digital converter (ADC) can be carried out using digital signals and at high speeds. Circuit elements are added to an ADC so that a first phase of testing may be carried out using a limited number of analog test voltages. The ADC may then be reconfigured using added circuit elements to disable conventional analog-to-digital conversion. A digital signal may then be applied to the ADC to rapidly test all switching elements used in analog-to-digital conversion. According to some implementations, testing times for ADCs may be reduced from hours to milliseconds.