Play mute circuit and method

A method for operating an amplifier circuit having a play mode and a mute mode, the method comprising:

• receiving an input signal at an input of an input stage, wherein a second stage has an input coupled to an output of the input stage, the second stage comprising a first switch circuit comprising first and second terminals, a plurality of resistive elements coupled between the first and second terminals of the first switch circuit, and a plurality of switches configured to control an equivalent resistance between the first and second terminals of the first switch circuit;
• during the play mode, generating an output signal at an output of the second stage based on the input signal, wherein, during the play mode, the second stage has a gain between the input of the second stage and the output of the second stage of a first value;
• detecting a temperature of the amplifier circuit;
• transitioning from the play mode to a reduced gain mode in response to detecting that the temperature of the amplifier circuit exceeds a first temperature threshold, the transitioning to the reduced gain mode comprising progressively turning off at least one of the plurality of switches while maintaining at least one other of the plurality of switches in an on state;
• transitioning to the mute mode by progressively turning off all of the plurality of switches in response to detecting that the temperature of the amplifier circuit exceeds a second temperature threshold higher than the first temperature threshold;
• and
• transitioning from the mute mode or the reduced gain mode to the play mode by progressively turning on the plurality of switches in response to detecting that the temperature of the amplifier circuit falls below a third temperature threshold.

A differential audio amplifier configured to operate in a play mode and a mute mode, the differential audio amplifier comprising:

• a differential input stage configured to receive a differential input audio signal;
• and
• a differential second stage having a differential input coupled to a differential output of the differential input stage, the differential second stage comprising first and second switch circuits, each of the first and second switch circuits comprising first and second terminals, a plurality of resistive elements coupled between the first and second terminals, and a plurality of switches configured to control an equivalent resistance between the first and second terminals, wherein:
• during the play mode, the differential audio amplifier is configured to generate a differential audio output signal at a differential output of the differential second stage based on the differential input audio signal, wherein, during the play mode, the differential second stage has a gain between the differential input of the differential second stage and the differential output of the differential second stage of a first value,
• during a transition from the mute mode to the play mode, the differential audio amplifier is configured to progressively increase the gain of the differential second stage from a second value to the first value by progressively turning on or off the plurality of switches of the first and second switch circuits, and
• during a transition from the play mode to the mute mode, the differential audio amplifier is configured to progressively decrease the gain of the differential second stage from the first value to the second value by progressively turning on or off the plurality of switches of the first and second switch circuits.