This disclosure generally provides a fingerprint sensor that derives a fingerprint by measuring capacitive sensing signals while modulating a reference voltage rail used to power the fingerprint sensor. In one embodiment, the fingerprint sensor is integrated into an electronic device which may include other components such as a display, I/O devices, speakers, and the like. To power these components, the electronic device may include a DC power supply which outputs reference voltages. When transmitting the reference voltages to the fingerprint sensor, the electronic device may modulate the voltages using a modulating signal. Because the reference voltages are used to power the components in the fingerprint sensor, modulating the rail voltages also causes the components coupled to the reference voltages to also modulate. While this modulation occurs, the fingerprint sensor measures resulting signals using a plurality of sensor electrodes which are then processed to derive a fingerprint.