Invention Grant
US07649417B1 Apparatus and method for input stage and bias canceller for an audio operational amplifier
有权
用于音频运算放大器的输入级和偏置消除器的装置和方法
- Patent Title: Apparatus and method for input stage and bias canceller for an audio operational amplifier
- Patent Title (中): 用于音频运算放大器的输入级和偏置消除器的装置和方法
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Application No.: US11752827Application Date: 2007-05-23
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Publication No.: US07649417B1Publication Date: 2010-01-19
- Inventor: Matsuro Koterasawa
- Applicant: Matsuro Koterasawa
- Applicant Address: US CA Santa Clara
- Assignee: National Semiconductor Corporation
- Current Assignee: National Semiconductor Corporation
- Current Assignee Address: US CA Santa Clara
- Agency: Darby & Darby P.C.
- Agent Matthew M. Gaffney
- Main IPC: H03F3/45
- IPC: H03F3/45

Abstract:
An input bias cancellation stage for an audio operational amplifier is provided. The input bias cancellation stage includes an input differential pair, a current mirror, and a bias duplicator transistor that substantially duplicates the input bias current. The bias duplicator transistor receives substantially the same emitter current as the transistors in the input differential pair, and has substantially the same Vce as the transistors in the input differential pair. The current mirror mirrors the duplicated bias current and subtracts it from the bases of the transistors in the input differential pair so that the input bias current is substantially cancelled.
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