Texas Instruments Corporation

Allan Nogueras Nielsen

Kim Nordtorp Madsen

Conventional muting circuitry for amplifiers (which usually uses clamps) generally has about 20-30 dB of attenuation. Here, an integrated circuit or IC is provided that includes an amplifier, switch networks, and a controller. The controller provides control signals to the switch network to provide mute functionality by actively muting the amplifier. In particular, feedback is provided through at least one of the switch networks to drive the output of the amplifier to null or ground so as to provide 70-80 dB (or more) of attenuation.

Active mute scheme for an amplifier

To reduce pop or click during turn-on, a method and apparatus are provided. Initially, a plurality of current sources in the amplifier is actuated. The amplifier is transitioned from an off-state to an on-state in a class B amplifier mode by de-coupling each input node of an output stage of the amplifier from a voltage rail, and the amplifier is transitioned from the on-state in the class B amplifier mode to an on-state in a class AB amplifier mode by actuating at least a portion of an intermediate circuit in the amplifier.

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Dallas, TX, United States of America

Allan Nogueras Nielsen