发明公开
- 专利标题： Microphone circuit
- 专利标题（中）： Mikrophonschaltung。
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申请号： EP87310974.8申请日： 1987-12-14
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公开(公告)号： EP0272068A2公开(公告)日： 1988-06-22
- 发明人: Murata, Yukio
- 申请人： NEC CORPORATION
- 申请人地址： 7-1, Shiba 5-chome Minato-ku Tokyo JP
- 专利权人： NEC CORPORATION
- 当前专利权人： NEC CORPORATION
- 当前专利权人地址： 7-1, Shiba 5-chome Minato-ku Tokyo JP
- 代理机构： Orchard, Oliver John
- 优先权： JP299246/86 19861215
- 主分类号： H04M1/60
- IPC分类号： H04M1/60 ; H04M9/08
摘要：
A microphone circuit includes a microphone unit (27) operated by a DC bias voltage for providing a microphone output signal superposed on the DC bias voltage, a constant current source (26) connectable in parallel with the microphone unit, a first control switch for controlling the parallel connection of the constant current source to change the DC bias voltage, and a voltage comparator (24) connected in parallel with the microphone unit for comparing the bias voltage with a predetermined reference voltage to detect the status of the control switch and to provide a control signal.
公开/授权文献
- EP0272068B1 Microphone circuit 公开/授权日：1993-03-10
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