Electronic device and method to estimate input power into resonant tank in resonant circuit

An electronic device to calculate input power input to a resonant tank in a resonant circuit, comprising:

• a bandpass filter, configured to receive a resonant current input to the resonant tank, and filter the resonant current to generate a first baseband current;
• a phase detection circuit, electrically connected to the bandpass filter, configured to calculate a phase difference between the first baseband current and a resonant tank voltage input to the resonant tank;
• a peak detection circuit, electrically connected to the bandpass filter, configured to generate a baseband current peak value according to the first baseband current;
• and
• a processor, electrically connected the phase detection circuit and the peak detection circuit, configured to perform a fast Fourier transform on the resonant tank voltage to obtain a resonant tank baseband voltage,
• wherein the processor is configured to calculate the input power according to the resonant tank baseband voltage, the baseband current peak value, and the phase difference.