Abstract: A system includes a tank circuit, a synchronization circuit, a transmitter, and a control circuit. The tank circuit is configured to receive a first signal transmitted from a near field communication reader. The synchronization circuit is configured to synchronize a clock to the first signal. The transmitter is configured to transmit data using the clock from the tank circuit to the near field communication reader using active load modulation. The control circuit is configured to disable the synchronization circuit during a modulation period of the active load modulation and to reduce energy remaining in the tank circuit at an end of the modulation period.

Abstract: An adaptive dual mode card emulation system (in Card Emulation Mode or PICC design) within an NFC device is disclosed to solve the strong field power delivering issue and also achieve longer communication range. The NFC device may be a NFC tag or an electronic device (such as a smartphone) operated in a card emulation mode. The NFC device comprises an antenna used for wireless communication. The adaptive dual mode card emulation system comprises a passive load modulation (PLM) module, an active load modulation (ALM) module and an automatic power control (APC) module. The APC module couples to both the ALM and PLM modules and selectably enables the ALM or PLM module depending on the strength of received carrier signal sent from an NFC reader.

Abstract: A system includes a tank circuit, a synchronization circuit, a transmitter, and a control circuit. The tank circuit is configured to receive a first signal transmitted from a near field communication reader. The synchronization circuit is configured to synchronize a clock to the first signal. The transmitter is configured to transmit data using the clock from the tank circuit to the near field communication reader using active load modulation. The control circuit is configured to disable the synchronization circuit during a modulation period of the active load modulation and to reduce energy remaining in the tank circuit at an end of the modulation period.

Abstract: An adaptive dual mode card emulation system (in Card Emulation Mode or PICC design) within an NFC device is disclosed to solve the strong field power delivering issue and also achieve longer communication range. The NFC device may be a NFC tag or an electronic device (such as a smartphone) operated in a card emulation mode. The NFC device comprises an antenna used for wireless communication. The adaptive dual mode card emulation system comprises a passive load modulation (PLM) module, an active load modulation (ALM) module and an automatic power control (APC) module. The APC module couples to both the ALM and PLM modules and selectably enables the ALM or PLM module depending on the strength of received carrier signal sent from an NFC reader.