Qualcomm Incorporated

Uma Chilakapati

Seyfollah Seyfollahi Bazarjani

Jeffrey Mark Hinrichs

Hui-Ya Liao Nelson

Guoqing Miao

Joseph Robert Fitzgerald

Khalid Junaid Sidiqi

Anurag Pulincherry

Khalid J Sidiqi

Joseph Fitzgerald

A multi-mode amplifier with configurable DC-coupled or AC-coupled output is described. In one design, the multi-mode amplifier includes an amplifier and at least one DC level shifting circuit. The amplifier receives and amplifies an input signal and provides an output signal that is suitable for DC coupling to a load in a DC-coupled mode and for AC coupling to the load in an AC-coupled mode. The at least one DC level shifting circuit performs DC level shifting for at least one (e.g., input and/or output) common-mode voltage of the amplifier and is controlled based on whether the amplifier is operating in the DC-coupled or AC-coupled mode. The amplifier operates between Vand Vsupplies in the DC-coupled mode and between Vand Vsupplies in the AC-coupled mode. The amplifier may include at least one gain stage, an internal DC level shifting circuit, and an output stage.

Amplifier with configurable DC-coupled or AC-coupled output

A digital offset is combined with an audio signal in the digital domain to cancel an output offset caused by one or more analog components processing the same audio signal. In this manner, the offset at the output of the audio signal path (e.g., at a power amplifier output) is reduced or eliminated. Consequently, audible artifacts, such as click-and-pop artifacts, can be reduced or eliminated. In audio devices operating in ground-referenced capless mode, power consumption is reduced because of reduced or eliminated direct current (DC) leakage current through speakers or headsets of such audio devices. In some circumstances, the digital offset in the digital domain may be applied at substantially all times of operation of the audio signal path.

Suppressing output offset in an audio device

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San Diego, CA, United States of America

Uma Chilakapati