The present disclosure provides an audio amplifier circuit, including: a modulator circuit configured to modulate an audio input signal into a pulse width modulation (PWM) signal; a switch stage circuit configured to receive the PWM signal and amplify the PWM signal; a demodulator circuit configured to receive and demodulate the amplified PWM signal to obtain a demodulated audio signal, and to output the demodulated audio signal to a speaker; and a feedback circuit configured to feed back the demodulated audio signal output by the demodulator circuit, and to output a feedback signal to an input end of the modulator circuit. Here, the feedback circuit includes an analog-to-digital converter and a loop filter. The switch stage circuit includes a driver and two gallium nitride (GaN) field effect transistors (FETs).

An amplifier system may include at least one alternating current (AC) input source, a first DC-DC converter configured to convert the AC voltage to a first rail voltage, a second DC-DC converter configured convert the AC voltage to a second rail voltage, and a Class D amplifier configured to receive the first rail voltage on a first positive rail from the first DC-DC converter and the second rail voltage on a second negative rail from the second DC-DC converter to reduce rail pumping of the first and second voltage rails.

A method for developing TDM data with embedded control data includes obtaining signal data and control data, formatting the signal data and the control data into a plurality of channels of a DIN signal, and transmitting the DIN signal on one line of a 3-bit TDM bus. A multichannel input device includes a control extractor receptive to the three-bit TDM bus and operative to extract CNTL data from the DIN data, a DAI receptive to the 3-bit TDM bus and the channel select input and operative to develop a SIGNAL data output, and a DAC block including a DAC, the DAC block being receptive to the SIGNAL data and the CNTL data.

A method for developing TDM data with embedded control data includes obtaining signal data and control data, formatting the signal data and the control data into a plurality of channels of a DIN signal, and transmitting the DIN signal on one line of a 3-bit TDM bus. A multichannel input device includes a control extractor receptive to the three-bit TDM bus and operative to extract CNTL data from the DIN data, a DAI receptive to the 3-bit TDM bus and the channel select input and operative to develop a SIGNAL data output, and a DAC block including a DAC, the DAC block being receptive to the SIGNAL data and the CNTL data.

Embodiments disclosed herein describe a wireless power receiver including a synchronous transistor rectifier using a Class-E or a Class-F amplifier. The wireless power receiver includes at least one radio frequency (RF) antenna configured to generate an alternating current (AC) waveform from received RF waves. The wireless power receiver further includes a power line configured to carry a first signal based on the AC current generated by the least one RF antenna, and a tap-line coupled to the power line, the tap-line being configured to carry a second signal. The second signal is based on the AC current generated by the least one RF antenna and distinct from the first signal. The wireless power receiver also includes a transistor coupled to at least the power line and the tap-line. The transistor is configured to provide a direct current (DC) waveform to a load based on the first and second signals.

A method applied in a driving circuit is disclosed. The driving circuit is coupled between a voltage source and a load and configured to drive the load. The method includes: forming, by the driving circuit, a first current from the voltage source to the load; and forming, by the driving circuit, a second current from the load back to the voltage source.

In accordance with an embodiment, a wireless power transmitter includes a charging surface, a transmitting antenna configured to generate an electromagnetic field extending above the charging surface, a sensing array disposed between the transmitting antenna and the charging surface, and a controller coupled to the sensing array. The sensing array includes a plurality of sensors. Each sensor of the plurality of sensors is configured to generate a respective signal indicative of a strength of the electromagnetic field. The controller is configured to detect a presence of a metallic object, other than a receiving antenna of a power receiver, in the electromagnetic field based on the respective signal generated by one or more sensors of the plurality of sensors.

In accordance with an embodiment, a wireless power transmitter includes a charging surface, a transmitting antenna configured to generate an electromagnetic field extending above the charging surface, a sensing array disposed between the transmitting antenna and the charging surface, and a controller coupled to the sensing array. The sensing array includes a plurality of sensors. Each sensor of the plurality of sensors is configured to generate a respective signal indicative of a strength of the electromagnetic field. The controller is configured to detect a presence of a metallic object, other than a receiving antenna of a power receiver, in the electromagnetic field based on the respective signal generated by one or more sensors of the plurality of sensors.

Systems and methods according to one or more embodiments are provided for sensing a current at an output of a switching amplifier. In one example, a system includes a first transistor switch coupled to a load configured to conduct a current in the load responsive to a first pulse width modulated control signal coupled to a gate terminal of the first transistor switch. The system further includes a second transistor switch configured to conduct the current in the load responsive to a second pulse width modulated control signal coupled to a gate terminal of the second transistor switch. A shielding switch is coupled between the load and a current sensing circuit, wherein the shielding switch is configured to provide a small signal voltage to the current sensing circuit in response to the second pulse width modulated control signal, the current sensing circuit is configured to sense the current traveling through the load responsive to the small signal voltage.

Systems and methods according to one or more embodiments are provided for sensing a current at an output of a switching amplifier. In one example, a system includes a first transistor switch coupled to a load configured to conduct a current in the load responsive to a first pulse width modulated control signal coupled to a gate terminal of the first transistor switch. The system further includes a second transistor switch configured to conduct the current in the load responsive to a second pulse width modulated control signal coupled to a gate terminal of the second transistor switch. A shielding switch is coupled between the load and a current sensing circuit, wherein the shielding switch is configured to provide a small signal voltage to the current sensing circuit in response to the second pulse width modulated control signal, the current sensing circuit is configured to sense the current traveling through the load responsive to the small signal voltage.