A low frequency loss correction circuit that improves the efficiency of a power amplifier at near-DC low frequencies The low frequency loss correction circuit can include a signal error detection circuit configured to produce an error signal in response to detecting one or more frequency components of a tracking signal below a cutoff frequency that are substantially attenuated through a capacitive path. The low frequency loss correction circuit can include a drive circuit configured to convert the error signal into a low frequency correction signal, and provide the low frequency correction signal to a voltage supply line, the low frequency correction signal including at least some of the one or more frequency components of the tracking signal below a cutoff frequency that are substantially attenuated through the capacitive path.

Bias circuits and methods for silicon-based amplifier architectures that are tolerant of supply and bias voltage variations, bias current variations, and transistor stack height, and compensate for poor output resistance characteristics. Embodiments include power amplifiers and low-noise amplifiers that utilize a cascode reference circuit to bias the final stages of a cascode amplifier under the control of a closed loop bias control circuit. The closed loop bias control circuit ensures that the current in the cascode reference circuit is approximately equal to a selected multiple of a known current value by adjusting the gate bias voltage to the final stage of the cascode amplifier. The final current through the cascode amplifier is a multiple of the current in the cascode reference circuit, based on a device scaling factor representing the relative sizes of the transistor devices in the cascode amplifier and in the cascode reference circuit.

An electronic device includes a waveform generator, a comparator, and an amplifier. The waveform generator receives a voltage from a power supply to the electronic device and outputs a voltage waveform signal. The comparator compares an input signal and the voltage waveform signal to output a first pulse-width-modulated signal. The amplifier receives the first pulse-width-modulated signal and outputs a second pulse-width-modulated signal.

A precharge circuit comprises a gain amplifier, a comparator, a reservoir capacitor, a switch, a current source, and a switching network. The gain amplifier has a gain G1 and receives an input voltage Vrefp. The gain amplifier outputs an amplified voltage G1Vrefp to the comparator, which compares G1Vrefp to a voltage across the reservoir capacitor. The comparator outputs a control signal for the switch based on the comparison. The switch couples the current source to the reservoir capacitor. The current from the current source charges the reservoir capacitor. The switching network couples the reservoir capacitor to an output of the precharge circuit during a first operating mode and provides the input voltage Vrefp to the output during a second operating mode.

A close-down pop reduction system and a method for close-down pop reduction in an audio amplifier assembly are disclosed. The switching power conversion system comprises a forward path having a compensator and a switching power stage and a signal path from an output of a comparator in the switching power stage to a sequence control unit. The signal path includes a close-down timing circuit configured to provide a timing signal. The sequence control unit is configured to eliminate the input signal, increase the switch frequency of the close-down pop reduction system and disable the switching power stage at a moment in time within a PWM pulse of the switching power stage. Hereby, it is e.g. possible to minimize the audible pop during close-down of audio amplifier assemblies.

Various embodiments of the present invention relate to a power amplification device and method, wherein the power amplification device can comprise: a power amplifier; a switch mode converter for controlling a bias of the power amplifier; a comparator for providing a switching signal to the switch mode converter according to an envelope signal; and a control unit for determining whether a switching frequency of the switch mode converter is within a specific band and applying an offset to the switching frequency so as to deviate from the specific band if the switching frequency of the switch mode converter is within the specific band. Various other embodiments can be carried out.

An amplifier circuit includes a sampling circuit and an amplifier connected to an output of the sampling circuit. A feedback capacitor is between an output terminal of the amplifier and an output terminal of the sampling circuit. A quantizer that includes a comparator is configured to quantize a voltage at the output terminal of the sampling circuit according to a comparison of a voltage at the output terminal of the sampling circuit to a voltage at the reference potential terminal of the comparator. The quantizer outputs a digital code according to the voltage comparison. A control circuit receives the digital code from the quantizer and stores the digital code in a register as a cancellation digital code. A digital-analog (D/A) converter outputs an analog signal in accordance with digital codes from the control circuit.

An audio amplifier circuit for providing an output signal to an audio transducer may include a power amplifier and a control circuit. The power amplifier may include an audio input for receiving an audio input signal, an audio output for generating the output signal based on the audio input signal, and a power supply input for receiving a power supply voltage, wherein the power supply voltage is variable among at least a first supply voltage and a second supply voltage greater than the first supply voltage. The control circuit may be configured to predict, based on one or more characteristics of a signal indicative of the output signal, an occurrence of a condition for changing the power supply voltage, and responsive to predicting the occurrence of the condition, change, at an approximate zero crossing of the signal indicative of the output signal, the power supply voltage.

A Class D amplifier having an integrating primary amplifier with an internal feedback, the amplifier further comprising a feedback loop with a filter of at least second order.

An apparatus is provided which comprises: a low-side switch; at least two high-side switches coupled to the low-side switch; a supply boost circuitry coupled to one of the at least two high-side switches; and a high-side switch selection circuit which is operable to enable one of the at least two high-side switches according to a relative difference between a signal and a threshold.