Patent ID: 8437696

Claim:
A near-field communication device for detecting and reading external RFID tags, the device comprising: a resonant loop antenna circuit including an antenna and a variable component, the antenna having a target range of operation for near-field communication where the antenna inductance is susceptible to interference that can alter the target range, the antenna circuit being tunable by adjusting the variable component; and an integrated circuit connected to the resonant loop antenna circuit, the integrated circuit comprising: a controller for controlling transmitting and receiving near-field communications signals via the resonant loop antenna circuit, an inductance detection circuit to detect changes in the antenna inductance indicative of incidents of interference due to an external object located proximate to the device, an antenna tuning circuit to adjust the variable component of the resonant loop antenna circuit to compensate for changes in antenna inductance detected by the inductance detection circuit to maintain the target range of operation, and a wake-on circuit responsive to a sufficient change in antenna inductance being detected by the inductance detection circuit to transition the controller from a low power sleep mode to a communications mode where the wake-on circuit is only again responsive to the sufficient change in antenna inductance as referenced to the adjusted resonant loop antenna circuit.