A class-D amplifier with multiple “nested” levels of feedback. The class-D amplifier surrounds an inner feedback loop, which takes the output of a switching amplifier and corrects for errors generated across the switching amplifier, with additional feedback loops that also take the output of the switching amplifier.

A Class D power amplification modulation system for self-adaptive adjustment of an audio signal is provided, including an amplification circuit module, a pulse width modulation (PWM) circuit module connected to the amplification circuit module, a frequency detection circuit module, a carrier generator module connected to the frequency detection circuit module, an amplitude detection circuit module, a direct current (DC) potential adjustment module connected to the amplitude detection circuit module, and a drive circuit module. A method, a device, a processor, and a computer-readable storage medium are also provided. The characteristics of the circuit in the signal time domain and frequency are improved by simultaneously controlling the amplitude and the frequency of the audio signal, to minimize power consumption of signals with different amplitudes and frequencies, and to improve EMI performance, or to balance the circuit power consumption and EMI characteristics.

A Class D power amplification modulation system for self-adaptive adjustment of an audio signal is provided, including an amplification circuit module, a pulse width modulation (PWM) circuit module connected to the amplification circuit module, a frequency detection circuit module, a carrier generator module connected to the frequency detection circuit module, an amplitude detection circuit module, a direct current (DC) potential adjustment module connected to the amplitude detection circuit module, and a drive circuit module. A method, a device, a processor, and a computer-readable storage medium are also provided. The characteristics of the circuit in the signal time domain and frequency are improved by simultaneously controlling the amplitude and the frequency of the audio signal, to minimize power consumption of signals with different amplitudes and frequencies, and to improve EMI performance, or to balance the circuit power consumption and EMI characteristics.

Power amplifier apparatuses and techniques for optimizing the design of power amplifiers are disclosed. In one aspect, a method for optimizing a power amplifier includes selecting a circuit topology for the power amplifier. The circuit topology includes one or more photoconductive switches and an impedance matching network including one or more parameter values representative of the impedance matching network or the photoconductive switches that can be adjusted. The method further includes selecting one or more optimization goals for the impedance matching network and the one or more photoconductive switches, and adjusting the one or more parameter values according to the one or more optimization goals. The one or more optimization goals include an efficiency at a particular power output.

A sound output device of the present disclosure includes a controller, a power amplifier, a low-pass filter, and a speaker. The controller includes first and second low-pass filters configured to remove high-frequency components of a sound input signal and a sound output signal, a first peak detection unit configured to detect a peak current of the sound input signal from which the high-frequency component has been removed, a second peak detection unit configured to detect a peak current of the sound output signal from which the high-frequency component has been removed, and a comparison unit configured to compare the peak current with the peak current and determine connection or disconnection of the speaker when a level of the peak current is equal to or higher than a certain level.

Systems, methods, and apparatus for an improved body tie construction are described. The improved body tie construction is configured to have a lower resistance body tie exists when the transistor is “off” (Vg approximately 0 volts). When the transistor is “on” (Vg>Vt), the resistance to the body tie is much higher, reducing the loss of performance associated with presence of body tie. Space efficient Body tie constructions adapted for cascode configurations are also described.

A system may include a Class-D stage comprising a first high-side switch coupled between a supply voltage and a first output terminal of the Class-D stage, a second high-side switch coupled between the supply voltage and a second output terminal of the Class-D stage, a first low-side switch coupled between a ground voltage and the first output terminal, and a second low-side switch coupled between the ground voltage and the second output terminal. The system may also include current sensing circuitry comprising a first sense resistor coupled between the first low-side switch and the ground voltage, such that an output current through a load coupled between the first output terminal and the second output terminal causes a first sense voltage proportional to the output current across the first sense resistor when the first low-side switch is activated. The current sensing circuitry may also include a second sense resistor coupled between the second low-side switch and the ground voltage, such that an output current through the load causes a second sense voltage proportional to the output current across the second sense resistor when the second low-side switch is activated. The system may also include measurement circuitry configured to measure the first sense voltage and the second sense voltage to determine the output current.

A system may include a Class-D stage comprising a first high-side switch coupled between a supply voltage and a first output terminal of the Class-D stage, a second high-side switch coupled between the supply voltage and a second output terminal of the Class-D stage, a first low-side switch coupled between a ground voltage and the first output terminal, and a second low-side switch coupled between the ground voltage and the second output terminal. The system may also include current sensing circuitry comprising a first sense resistor coupled between the first high-side switch and the supply voltage, such that an output current through a load coupled between the first output terminal and the second output terminal causes a first sense voltage proportional to the output current across the first sense resistor when the first high-side switch is activated. The current sensing circuitry may also include a second sense resistor coupled between the second high-side switch and the supply voltage, such that an output current through the load causes a second sense voltage proportional to the output current across the second sense resistor when the second high-side switch is activated. The system may also include measurement circuitry configured to measure the first sense voltage and the second sense voltage to determine the output current.

A hearable has an audio amplifier circuit coupled to a speaker as a load. The amplifier circuit has current source drive, which attenuates electromagnetically coupled noise of the speaker. In other instances, the amplifier circuit has a first amplifier mode and a second amplifier mode, wherein in the first amplifier mode the amplifier circuit becomes configured to drive the speaker as a voltage source, and in the second amplifier mode the amplifier circuit becomes configured to drive the speaker as a current source. Control logic varies the amplifier circuit between i) the first amplifier mode for larger amplitudes of the audio signal, and ii) the second amplifier mode for smaller amplitudes of the audio signal. Other aspects are also described and claimed.

A hearable has an audio amplifier circuit coupled to a speaker as a load. The amplifier circuit has current source drive, which attenuates electromagnetically coupled noise of the speaker. In other instances, the amplifier circuit has a first amplifier mode and a second amplifier mode, wherein in the first amplifier mode the amplifier circuit becomes configured to drive the speaker as a voltage source, and in the second amplifier mode the amplifier circuit becomes configured to drive the speaker as a current source. Control logic varies the amplifier circuit between i) the first amplifier mode for larger amplitudes of the audio signal, and ii) the second amplifier mode for smaller amplitudes of the audio signal. Other aspects are also described and claimed.