Excitation circuit, vibration device, and vehicle

An excitation circuit comprising:

• an output circuit including a series circuit of a first switch and a second switch connected to a DC power supply, and including a connection point, between the first switch and the second switch, to which a piezoelectric element is connected;
• a current detection circuit to detect at least one of a current flowing through the first switch and a current flowing through the second switch, and output a detection signal indicating a value based on the detected current;
• and
• a control circuit to execute switching processing in which the first switch and the second switch are complementarily switched on and off at a switching frequency corresponding to a predetermined frequency, in order to apply a voltage of the predetermined frequency from the output circuit to the piezoelectric element, and that has a search mode to determine a resonant frequency of a vibrator including an object vibrated by the piezoelectric element and the piezoelectric element, based on a value indicated by the detection signal outputted from the current detection circuit.