A Class-F power amplifier includes a harmonic matching network topology comprised of circuit elements configured relative to an output network of the power amplifier. The harmonic matching network topology suppresses higher-order harmonics in such a power amplifier and includes coupled-line capacitors and open-stubs that introduce harmonic terminations in the output network, and quarter-wavelength transmission lines to match an overall network to a 50-ohm output load. The harmonic matching network topology enables the power amplifier to exhibit desired performance characteristics in specific frequency ranges for high-power applications.

A Class-F power amplifier includes a harmonic matching network topology comprised of circuit elements configured relative to an output network of the power amplifier. The harmonic matching network topology suppresses higher-order harmonics in such a power amplifier and includes coupled-line capacitors and open-stubs that introduce harmonic terminations in the output network, and quarter-wavelength transmission lines to match an overall network to a 50-ohm output load. The harmonic matching network topology enables the power amplifier to exhibit desired performance characteristics in specific frequency ranges for high-power applications.

An audio amplifier system is described herein, comprising: an amplifier adapted to amplify an audio signal and comprising an output enable/disable input, the amplifier further adapted to receive an output enable signal at the output enable/disable input that enables/disables an output of the amplifier; a Zobel network connected to the output of the audio amplifier and comprising a Zobel capacitor and a Zobel resistor arranged such that they form a high pass frequency filter function and wherein the Zobel network is adapted to be substantially resistive when a frequency of an audio signal output from the audio amplifier is within a first frequency range; a mirroring resistor connected in parallel to the Zobel resistor and adapted to mirror a power that is dissipated in the Zobel resistor, and wherein a printed circuit board upon which the mirroring resistor is located is adapted to conduct heat generated by the mirroring resistor; a negative temperature coefficient (NTC) resistor located in close proximity to the mirroring resistor to receive the conducted heat from the mirroring resistor and which is adapted to change its resistance in response to the transferred heat such that its resistance goes down as a temperature of the NTC resistor increases; and a circuit adapted to generate the output enable signal, wherein the circuit generates an output enable signal that enables the output of the amplifier when the temperature of the Zobel resistor is below a first temperature, and wherein the circuit generates an output enable signal that disables the output of the amplifier when the temperature of the Zobel resistor is substantially the same or above the first temperature.

An audio amplifier system is described herein, comprising: an amplifier adapted to amplify an audio signal and comprising an output enable/disable input, the amplifier further adapted to receive an output enable signal at the output enable/disable input that enables/disables an output of the amplifier; a Zobel network connected to the output of the audio amplifier and comprising a Zobel capacitor and a Zobel resistor arranged such that they form a high pass frequency filter function and wherein the Zobel network is adapted to be substantially resistive when a frequency of an audio signal output from the audio amplifier is within a first frequency range; a mirroring resistor connected in parallel to the Zobel resistor and adapted to mirror a power that is dissipated in the Zobel resistor, and wherein a printed circuit board upon which the mirroring resistor is located is adapted to conduct heat generated by the mirroring resistor; a negative temperature coefficient (NTC) resistor located in close proximity to the mirroring resistor to receive the conducted heat from the mirroring resistor and which is adapted to change its resistance in response to the transferred heat such that its resistance goes down as a temperature of the NTC resistor increases; and a circuit adapted to generate the output enable signal, wherein the circuit generates an output enable signal that enables the output of the amplifier when the temperature of the Zobel resistor is below a first temperature, and wherein the circuit generates an output enable signal that disables the output of the amplifier when the temperature of the Zobel resistor is substantially the same or above the first temperature.

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 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.

The disclosure presents a method and an amplifier system for minimizing variation in an acoustical signal caused by variation in gain of an amplifier, comprising a battery for providing a supply voltage to the amplifier, a digital signal processor for providing the acoustical signal to the amplifier, a controller unit receiving an enablement signal when the supply voltage is in an offset mode, and based on the enablement signal requesting a measured voltage during a time period, and a first analog-to-digital converter configured for measuring the supply voltage to the amplifier when receiving the request from the controller unit or the first analog-to-digital converter is configured for measuring the supply voltage to the amplifier continuously, and where variations in the measured voltage relates to variations in the supply voltage during the time period. Furthermore, the controller unit is configured to predict offset modes (i.e. changes) in the supply voltage based on the enablement signals and a fitting of the measured voltages, and wherein the controller unit is configured to generate a compensating signal based on the fitting and transmit the compensating signal to the digital signal processor, the digital signal processor is then configured to minimize variation in the acoustical signal at the output of the amplifier by compensating the variation in gain of the amplifier based on the compensating signal.

The present invention relates to a speaker driver and an operation method thereof and includes an amp part configured to output a pulse voltage, in which an input signal is amplified on the basis of a supply voltage, to drive a capacitive speaker that generates sound by a driving voltage so that the driving voltage formed by filtering the pulse voltage is applied to the capacitive speaker, and a controller configured to adjust a magnitude of an input audio signal in a high frequency range and transmit the input audio signal to the amp part as the input signal to limit an overcurrent applied to the capacitive speaker by the driving voltage having a high frequency.

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.