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Amplifiers

  • US 10,243,524 B2
  • Filed: 02/23/2018
  • Issued: 03/26/2019
  • Est. Priority Date: 02/28/2017
  • Status: Active Grant
First Claim
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1. An amplifier circuit for amplifying an audio signal, comprising:

  • a voltage regulator having an input node for receiving an input voltage and an output node for outputting an output voltage, the voltage regulator comprising an output capacitor coupled to the output node;

    an amplifier connected to receive the output voltage from said output node of the voltage regulator as a supply voltage;

    the voltage regulator being operable in a voltage-control mode to maintain the output voltage at a nominal output voltage and in current-control mode to apply current limiting so as to limit an input current drawn by the voltage regulator via the input node so as not to exceed a defined input current limit; and

    a controller for defining the nominal output voltage;

    wherein the controller is operable in a first mode to define the nominal output voltage so as not to exceed a first voltage magnitude and is operable in a second mode to define the nominal output voltage to be equal to a second voltage magnitude, the second voltage magnitude being greater than the first voltage magnitude;

    wherein the controller is configured to monitor an indication of the level of the audio signal for a high-amplitude part of the audio signal that could result in the voltage regulator operating in the current-control mode to apply current limiting; and

    wherein the controller is configured to operate in said first mode until such a high-amplitude part of the audio signal is detected and, on such detection to operate in the second mode of operation until such a high-amplitude part of the audio signal has been amplified;

    wherein the second voltage magnitude is greater than required for voltage headroom for amplifying the high-amplitude part of the audio signal so as to allow for a voltage droop of the output voltage over a plurality of switching cycles of the voltage regulator when operating in the current-control mode.

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