INPUT CURRENT LIMITED POWER SUPPLY AND AUDIO POWER AMPLIFIER FOR HIGH POWER REPRODUCTION OF NONDETERMINISTIC SIGNALS

摘要

A method and apparatus for amplifying audio signals without exceeding an input current limit budgeted for the audio power amplifier circuit includes an intermediate energy storage between a battery and the audio power amplifier which provides an energy reserve to support amplifying peaks where the peaks have a peak power that is greater than the power that can be drawn from the battery due to the input current limit. Speech signals, which include substantial periodic content having short peaks relative to a pitch period, can be amplified without depleting the intermediate energy storage, allowing the intermediate energy storage to recover after a peak and before occurrence of a next peak. When an audio signal is amplified that results in depletion of the intermediate energy storage, a depletion recovery circuit reduces the overall audio gain to reduce the power demand of the audio power amplifier so as to substantially avoid distortion.

主权项

1. A method for powering an audio power amplifier, comprising:
boosting a voltage level of a battery to a boost voltage level across a boost capacitor at an output of a boost stage without exceeding a preselected input current limit, the boost voltage level being higher than the voltage level of the battery and higher than a supply voltage required for the audio power amplifier to output a predefined maximum peak power into a load; deriving the supply voltage from the boost voltage and providing the supply voltage to the audio power amplifier to power the audio power amplifier; the audio power amplifier amplifying an input signal to produce an amplified signal; comparing a state of charge indication parameter to a depletion threshold, wherein the state of charge indication parameter is dependent on the boost voltage; and when the state of charge indication parameter is below the depletion threshold, adjusting a gain of a pre-amplifier that provides the input signal to the audio power amplifier.