Stmicroelectronics (China) Investment Co. Ltd

Tianhao Xiong

Gang Wu

Dongyang Tian

A near field communication (NFC) reader detects whether NFC devices are passive NFC devices or active NFC devices. The NFC reader outputs an interrogation signal and a carrier signal. When the NFC reader receives a response signal from an NFC device responsive to the interrogation signal, the NFC reader adjusts the frequency of the carrier signal before the end of the response signal. The NFC reader determines whether the NFC device is a passive NFC device or an active NFC device based on characteristics of the remaining portion of the response signal.

System and method for distinguishing between active and passive NFC devices based on adjustment of carrier frequency

A near field communication (NFC) reader detects whether NFC devices are passive NFC devices or active NFC devices. The NFC reader outputs an interrogation signal and a carrier signal. When the NFC reader receives a response signal from an NFC device responsive to the interrogation signal, the NFC reader interrupts the carrier signal before the end of the response signal. The NFC reader determines whether the NFC device is a passive NFC device or an active NFC device depending on whether the response signal continues during the interruption of the interrogation signal.

System and method for distinguishing between active and passive NFC devices

In one aspect, the NFC device includes an antenna that includes first and second terminals, a first resistor on a first current path, and a second resistor on a second current path. The NFC device includes a first switch that switches between open and closed states, where the first switch couples the first current path to the first terminal in the closed state. The NFC device includes a second switch that switches between open and closed states, where the second switch couples the second current path to the second terminal in the closed state. The NFC device includes a controller in communication with the first and second switches and configured to set a Q factor of the antenna to a first or second value by operating the first and second switches.

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Shanghai, China

Tianhao Xiong