Pulse-width modulation audio amplifier having compensated regulation loop
In some embodiments, an audio amplifier can include an input for receiving a signal to be amplified, and an amplification stage configured to amplify the signal based on pulse width modulation and provide the amplified signal at an output node. The audio amplifier can further include a feedback circuit implemented between the output node and the input node. The feedback circuit can include a series arrangement of a high bandwidth input common mode loop and a low bandwidth output common mode loop, with the low bandwidth output common mode loop configured to provide a desired phase change for the high bandwidth input common mode loop.
1 . An audio amplifier comprising:
an input node for receiving a signal;
an amplification stage configured to amplify the signal with pulse width modulation and provide an amplified signal at an output node; and
a feedback circuit implemented between the output node and the input node, the feedback circuit including an input common mode loop and an output common mode loop configured to provide a phase change for the input common mode loop.
2 . The audio amplifier of claim 1 wherein the audio amplifier is configured as a half-bridge amplifier.
3 . The audio amplifier of claim 1 wherein the audio amplifier is configured as a Class D amplifier.
4 . The audio amplifier of claim 1 wherein the output common mode loop is configured such that the phase change includes a desired lead in phase.
5 . The audio amplifier of claim 1 wherein the input common mode loop includes a high bandwidth capability, and the output common mode loop includes a low bandwidth capability.
6 . A method for amplifying an audio signal, the method comprising:
receiving an audio signal at an input node of an amplifier;
amplifying the audio signal with pulse width modulation to provide an amplified audio signal at an output node; and
providing a feedback from the output node to the input node, the providing including passing a feedback signal through an input common mode loop and through an output common mode loop that introduces a phase change for the input common mode loop.
7 . The method of claim 6 wherein the amplifier includes a half-bridge amplifier.
8 . The method of claim 6 wherein the amplifier includes a Class D amplifier.
9 . The method of claim 6 wherein the output common mode loop is configured such that the phase change includes a desired lead in phase.
10 . The method of claim 6 wherein the input common mode loop includes a high bandwidth capability, and the output common mode loop includes a low bandwidth capability.
11 . A wireless device comprising:
an antenna for receiving a wireless signal;
an audio amplifier circuit including an input node for receiving a signal representative of the wireless signal, and an amplification stage configured to amplify the signal with pulse width modulation and provide an amplified signal at an output node, the audio amplifier circuit further including a feedback circuit implemented between the output node and the input node, the feedback circuit including an input common mode loop and an output common mode loop configured to provide a phase change for the input common mode loop; and
a speaker coupled to the output node and configured to generate sound waves based on the amplified signal.
12 . The wireless device of claim 11 wherein the wireless device is a wireless headphone or a wireless earphone.
13 . The wireless device of claim 11 wherein the audio amplifier circuit includes a half-bridge amplifier.
14 . The wireless device of claim 11 wherein the audio amplifier circuit includes a Class D amplifier.
15 . The wireless device of claim 11 wherein the output common mode loop is configured such that the phase change includes a desired lead in phase.
16 . The wireless device of claim 11 wherein the input common mode loop includes a high bandwidth capability, and the output common mode loop includes a low bandwidth capability.