A wireless charging device , comprising: a charging pad that comprises: a first resonator coil operable at a first frequency band; a second resonator coil operable at a second frequency band; an exciter coil magnetically coupled to both the first resonator coil and the second resonator coil , wherein the exciter coil is operable to provide a first AC voltage to the first resonator coil at a first frequency within the first frequency band, and to provide a second AC voltage to the second resonator coil at a second frequency within the second frequency band; and an excitation unit that comprises output terminals electrically coupled to the exciter coil and configured to drive the first resonator coil with the first AC voltage at the first frequency and the second resonator coil with the second AC voltage at the second frequency via the exciter coil ; and a control unit that is configured to generate a first frequency control signal and a second frequency control signal to feed at least one of the first frequency control signal and the second frequency control signal to the excitation unit so as to selectively cause the first resonator coil to be driven with the first AC voltage or the second resonator coil to be driven with the second AC voltage by the excitation unit . a charging pad that comprises: a first resonator coil operable at a first frequency band; a second resonator coil operable at a second frequency band; an exciter coil magnetically coupled to both the first resonator coil and the second resonator coil , wherein the exciter coil is operable to provide a first AC voltage to the first resonator coil at a first frequency within the first frequency band, and to provide a second AC voltage to the second resonator coil at a second frequency within the second frequency band; and an excitation unit that comprises output terminals electrically coupled to the exciter coil and configured to drive the first resonator coil with the first AC voltage at the first frequency and the second resonator coil with the second AC voltage at the second frequency via the exciter coil ; and a first resonator coil operable at a first frequency band; a second resonator coil operable at a second frequency band; an exciter coil magnetically coupled to both the first resonator coil and the second resonator coil , wherein the exciter coil is operable to provide a first AC voltage to the first resonator coil at a first frequency within the first frequency band, and to provide a second AC voltage to the second resonator coil at a second frequency within the second frequency band; and an excitation unit that comprises output terminals electrically coupled to the exciter coil and configured to drive the first resonator coil with the first AC voltage at the first frequency and the second resonator coil with the second AC voltage at the second frequency via the exciter coil ; and a control unit that is configured to generate a first frequency control signal and a second frequency control signal to feed at least one of the first frequency control signal and the second frequency control signal to the excitation unit so as to selectively cause the first resonator coil to be driven with the first AC voltage or the second resonator coil to be driven with the second AC voltage by the excitation unit . <EOS>