Invention Grant
- Patent Title: High output impedance audio amplifier for noise rejection
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Application No.: US16889630Application Date: 2020-06-01
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Publication No.: US11166106B2Publication Date: 2021-11-02
- Inventor: Michael B. Nussbaum , Roderick B. Hogan , Todd K. Moyer
- Applicant: Apple Inc.
- Applicant Address: US CA Cupertino
- Assignee: Apple Inc.
- Current Assignee: Apple Inc.
- Current Assignee Address: US CA Cupertino
- Agency: Womble Bond Dickinson (US) LLP
- Main IPC: H04R9/06
- IPC: H04R9/06 ; H03F3/217 ; H03K19/094 ; H04R1/10 ; H03K5/156

Abstract:
A hearable has an audio amplifier circuit coupled to a speaker as a load. The amplifier circuit has current source drive, which attenuates electromagnetically coupled noise of the speaker. In other instances, the amplifier circuit has a first amplifier mode and a second amplifier mode, wherein in the first amplifier mode the amplifier circuit becomes configured to drive the speaker as a voltage source, and in the second amplifier mode the amplifier circuit becomes configured to drive the speaker as a current source. Control logic varies the amplifier circuit between i) the first amplifier mode for larger amplitudes of the audio signal, and ii) the second amplifier mode for smaller amplitudes of the audio signal. Other aspects are also described and claimed.
Public/Granted literature
- US20200351593A1 HIGH OUTPUT IMPEDANCE AUDIO AMPLIFIER FOR NOISE REJECTION Public/Granted day:2020-11-05
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