In one aspect, a fingerprint sensor device includes a substrate and a sensor chip disposed over the substrate. The sensor chip includes an array of sensor pixels configured to generate fingerprint data by sensing ridges and valleys of a surface of a finger contacting the fingerprint sensor device. Each sensor pixel includes a single sensor electrode an amplifier having an inverting terminal electrically connected to the sensor electrode and a non-inverting terminal electrically connected to a drive signal. The drive signal generates electric fields between the sensor electrode and at least one of the ridges and valleys of the surface of the finger contacting the fingerprint sensor device to generate a variable capacitor having a variable capacitance based at least partly on a distance between the sensor electrode and the at least one of the ridges and valleys of the finger.