A class-D amplifier with good signal-to-noise ratio (SNR) performance is shown. The class-D amplifier includes a loop filter, a pulse-width modulation signal generator, a gate driver, a power driver, and a feedback circuit, which are configured to establish a closed amplification loop. The feedback circuit is configured to establish a feedback path. The class-D amplifier further includes a feedback breaker. The feedback breaker breaks the feedback path in response to conditions in which there no-signal information in the class-D amplifier.

Systems and methods for protecting a loudspeaker from excessive excursion include an audio source, an adaptive excursion protection filter, an audio clipper, an inverse excursion protection filter, an amplifier and a loudspeaker. The system performs operations including receiving an audio signal, applying an excursion protection filter, the excursion protection filter adapting in real-time to one or more speaker conditions, clipping the audio signal, applying an inverse excursion protection filter, and amplifying, using an amplification circuit, the audio signal for output to the speaker.

A power control system for audio power amplifiers, especially in the automotive segment, dynamically controlling the output voltage through the reading of the input and output currents, and other parameters, automatically adjusting the amplifier to the load and to the operation conditions, allowing that the amplifier always operates within the safe operation range.

The present invention is in the field of booster stage circuit for a power amplifier, and an external supply voltage power amplifier comprising said booster stage circuit, such as for amplifying an electronic signal to a speaker system. These amplifiers may be provided with an external supply voltage.

This application relates to method and apparatus for driving acoustic transducers, such as speakers or haptic transducers. A transducer driver circuit (200) has a hysteretic comparator (201) configured to compare, with hysteresis, an input signal (S.sub.IN) received at a first comparator input to a feedback signal (S.sub.FB) received at a second comparator input. Based on the comparison the hysteretic comparator (201) generates a pulse-width modulation (PWM) signal (S.sub.PWM) at a comparator output (206). An inductor (203) is coupled between the comparator output and an output node (204). In use a resistive component (208), which may comprise the transducer (301) is coupled to output node (204). The inductor (203) and resistive component (208) provide filtering to the PWM signal (S.sub.PWM). A feedback path extends between the output node (204) and the second comparator input to provide the feedback signal (S.sub.FB).

A wideband envelope modulator comprises a direct current (DC)-to-DC switching converter connected in series with a linear amplitude modulator (LAM). The DC-DC switching converter includes a pulse-width modulator that generates a PWM signal with modulated pulse widths representing a time varying magnitude of an input envelope signal or a pulse-density modulator that generates a PDM signal with a modulated pulse density representing the time varying magnitude of the input envelope signal, a field-effect transistor (FET) driver stage that generates a differential PWM or PDM drive signal, a high-power output switching stage that is driven by the PWM or PDM drive signal, and an output energy storage network including a low-pass filter (LPF) of order greater than two that filters a switching voltage produced at an output switching node of the high-power output switching stage.

A wideband envelope modulator comprises a direct current (DC)-to-DC switching converter connected in series with a linear amplitude modulator (LAM). The DC-DC switching converter includes a pulse-width modulator that generates a PWM signal with modulated pulse widths representing a time varying magnitude of an input envelope signal or a pulse-density modulator that generates a PDM signal with a modulated pulse density representing the time varying magnitude of the input envelope signal, a field-effect transistor (FET) driver stage that generates a differential PWM or PDM drive signal, a high-power output switching stage that is driven by the PWM or PDM drive signal, and an output energy storage network including a low-pass filter (LPF) of order greater than two that filters a switching voltage produced at an output switching node of the high-power output switching stage.

Certain aspects of the present disclosure are generally directed to circuitry and techniques for voltage-to-current conversion. For example, certain aspects provide a circuit for signal amplification including a first amplifier; a first transistor, a gate of the first transistor being coupled to an output of the first amplifier and a drain of the first transistor being coupled to an output node of circuit; a first resistive element coupled between a first input node of the circuit and an input of the first amplifier; a second amplifier; a second transistor, a gate of the second transistor being coupled to an output of the second amplifier and a drain of the second transistor being coupled to the output node of circuit; and a second resistive element coupled between a second input node of the circuit and an input of the second amplifier.

An exemplary system and method is disclosed employing a floating inverter amplifier comprising an inverter-based circuit comprising an input configured to be switchable between a floating reservoir capacitor during a first phase of operation and to a device power source during a second phase of operation. In some embodiments, the floating inverter amplifier is further configured for current reuse and dynamic bias. In other embodiments, the floating inverter amplifier is further configured with a dynamic cascode mechanism that does not need any additional bias voltage. The dynamic cascode mechanism may be used in combination with 2-step fast-settling operation to provide high-gain and high-speed noise suppression operation.

The present disclosure relates to circuitry comprising: amplifier circuitry configured to receive a variable supply voltage, wherein the supply voltage varies according to an output signal of the amplifier circuitry; monitoring circuitry configured to monitor one or more parameters of an output signal of the amplifier circuitry; and processing circuitry configured to receive an indication of the voltage of the variable supply voltage and an indication of the monitored parameters from the monitoring circuitry and to apply a correction to one or more of the monitored parameters to compensate for coupling between the variable supply voltage and the monitoring circuitry.