A device of one aspect of the present invention includes a receiver to receive a modulation signal that has been subjected to frequency shift keying division ratio. The receiver includes a first demodulator and a demodulation control signal generator. The demodulation control signal generator includes a first frequency divider, a frequency control signal generator, and an oscillator. The first frequency divider divides a frequency of one of the modulation signal and the demodulation control signal by a first or second reception division ratio. The frequency control signal generator generates a frequency control signal based on a frequency of the other of the modulation signal and the demodulation control signal, and a frequency of the one of the modulation signal and the demodulation control signal obtained by division by the first or second reception division ratio. The oscillator generates the demodulation control signal based on the frequency control signal.

A method for phase compensating a power factor correction circuit is provided. Firstly, a present current value of an input current is sampled, and the sampled signal is filtered. Then, a present waveform of the input current corresponding to the present current value of the filtered sampled signal and a previous waveform of the input current corresponding to a previous current value of the filtered sampled signal are predicted, and a current error signal is generated according to a difference between the present waveform and the previous waveform. Then, the current error signal is adjusted, and an adjusted signal is generated. Then, a feedforward signal is added to the adjusted signal, and a phase compensation signal. Then, a current control signal is added to the phase compensation signal, and a pulse width modulation signal is generated to control a switching circuit.

A method for phase compensating a power factor correction circuit is provided. Firstly, a present current value of an input current is sampled, and the sampled signal is filtered. Then, a present waveform of the input current corresponding to the present current value of the filtered sampled signal and a previous waveform of the input current corresponding to a previous current value of the filtered sampled signal are predicted, and a current error signal is generated according to a difference between the present waveform and the previous waveform. Then, the current error signal is adjusted, and an adjusted signal is generated. Then, a feedforward signal is added to the adjusted signal, and a phase compensation signal. Then, a current control signal is added to the phase compensation signal, and a pulse width modulation signal is generated to control a switching circuit.

Example implementations may relate to a rotary transformer configured to transmit data. In some implementations, the rotary transformer may include a primary transformer component with a primary winding magnetically coupled to a secondary transformer component with a secondary winding. The rotary transformer may also include a resonant circuit including a frequency determining element and an amplifier. The frequency determining element may consist of the primary and secondary windings connected in parallel to respective capacitors. The primary transformer component may be coupled to a fixed-frequency signal generator. The rotary transformer may include a modulator coupled to the secondary transformer component and configured to vary the phase of the resonant circuit to generate an output signal and a demodulator coupled to the primary transformer component and configured to demodulate the output signal.

Example implementations may relate to a rotary transformer configured to transmit data. In some implementations, the rotary transformer may include a primary transformer component with a primary winding magnetically coupled to a secondary transformer component with a secondary winding. The rotary transformer may also include a resonant circuit including a frequency determining element and an amplifier. The frequency determining element may consist of the primary and secondary windings connected in parallel to respective capacitors. The primary transformer component may be coupled to a fixed-frequency signal generator. The rotary transformer may include a modulator coupled to the secondary transformer component and configured to vary the phase of the resonant circuit to generate an output signal and a demodulator coupled to the primary transformer component and configured to demodulate the output signal.

A system for phase imbalance calibration, including: an in-phase (I) signal channel including an analog-to-digital converter (ADC) for sampling an I signal to provide a sampled I signal; a quadrature (Q) signal channel including an ADC for sampling a Q signal to provide a sampled Q signal; a sampling clock for controlling the sampling of the ADC on the I signal channel and the sampling of the ADC on the Q signal channel; and sampling clock delay circuitry for adjusting one of a sampling start time of the ADC on the I channel and a sampling start time of the ADC on the Q channel relative to one another such that the sampled I signal and the sampled Q signal are in phase.