Near field communication NFC apparatus and open-loop control method

A method, comprising:

• receiving, by a clock extractor of a near field communication (NFC) apparatus, a first carrier signal from an NFC card reader;
• performing, by the clock extractor, clock recovery based on the first carrier signal to obtain a field clock signal;
• performing, by a digital phase-locked loop of the NFC apparatus, frequency tracking on the field clock signal to output a first clock signal;
• performing, by a digital baseband chip of the NFC apparatus, load modulation based on the first clock signal to generate a second carrier signal;
• receiving, by a controller of the NFC apparatus, the first clock signal from the digital phase-locked loop;
• performing, by the controller, frequency multiplication on the first clock signal to obtain a second clock signal;
• sampling, by the controller, the field clock signal using the second clock signal to obtain a sampling result;
• detecting, by the controller, a frequency of the field clock signal or a phase of the field clock signal based on the sampling result to obtain a frequency detection result or a phase detection result;
• and
• selectively controlling, by the controller, the digital phase-locked loop based on the frequency detection result or the phase detection result.