Abstract: A method for a near-field communication (NFC) tag to perform NFC and wireless power transfer (WPT) with an NFC reader, the NFC tag having an antenna resonant circuit, of which a quality factor (Q-factor) is no lower than 50 in a high-Q mode of the NFC tag, and no higher than 25 in a low-Q mode of the NFC tag. The method includes continuously preforming steps of detecting an NFC radio frequency (RF) field generated by the NFC reader, measuring strength of the NFC RF field, operating in the high-Q mode for the WPT upon determining that the strength of the NFC RF field is larger than a predetermined threshold, operating in the low-Q mode for the NFC upon determining that the strength of the NFC RF field is smaller than the predetermined threshold, and transmitting a response back to the NFC reader.

Abstract: A device for near-field communication (NFC) and wireless power reception (WPR) using a magnetic field. The device has an antenna resonant circuit. The antenna resonant circuit includes an antenna for magnetic flux of the magnetic field to flow therethrough, to thereby receive a NFC signal during the NFC and receive wireless power during the WPR, and a multi-Q antenna matching circuit configured to adjust an impedance of the antenna to thereby adjust a quality factor (Q-factor) of the antenna resonant circuit. The multi-Q antenna matching circuit is configured to switch between a high-Q mode for the WPR and a low-Q mode for the NFC, based on whether strength of the magnetic field is larger than a predetermined threshold. The device may also include two separate antenna resonant circuits, of which the Q-factors are respectively no higher than 25 and no lower than 50.