An analog-to-digital converter (ADC) comprising successive approximation circuitry, a capacitive analog-to-digital converter (CDAC), and capacitor mismatch measurement circuitry. The successive approximation circuitry is configured to control conversion of an analog signal to a digital value. The CDAC is coupled to the successive approximation circuitry. The CDAC includes a plurality of capacitors. The capacitor mismatch measurement circuitry is coupled to the CDAC. The capacitor mismatch measurement circuitry includes a first oscillator circuit, a second oscillator circuit, and counter circuitry. The first oscillator circuit is configured to oscillate at a frequency determined by a capacitance of one of the capacitors. The second oscillator circuit is configured to generate a predetermined time interval. The counter circuitry is configured to count a number of cycles of oscillation of the first oscillator in the predetermined time interval.