PIEZOELECTRIC MEMS MICROPHONE

PROBLEM TO BE SOLVED: To obtain a high sensitivity low noise piezoelectric MEMS microphone suitable for small and thin package mounting, by eliminating the problem that substantial characteristics deteriorate when reducing the capacity of back cavity.SOLUTION: A sense electrode film 22, a sense piez...

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Hauptverfasser:	FUJIWARA SO, YAMAZAKI KIMIYOSHI, SESHIMOTO AKIRA
Format:	Patent
Sprache:	eng ; jpn
Schlagworte:	DEAF-AID SETS ELECTRIC COMMUNICATION TECHNIQUE ELECTRICITY LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKEACOUSTIC ELECTROMECHANICAL TRANSDUCERS PUBLIC ADDRESS SYSTEMS
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Zusammenfassung:	PROBLEM TO BE SOLVED: To obtain a high sensitivity low noise piezoelectric MEMS microphone suitable for small and thin package mounting, by eliminating the problem that substantial characteristics deteriorate when reducing the capacity of back cavity.SOLUTION: A sense electrode film 22, a sense piezoelectric film 21a, a drive piezoelectric film 21b, a reference electrode film 26, a drive electrode film 23, and a support film 25 are provided as a diaphragm, an amplifier circuit 24 for amplifying a sense signal outputted from the sense electrode film 22 is provided, and vibration (amplitude) of the diaphragm due to acoustic signal pressure is suppressed by feeding a signal, amplified by the amplifier circuit 24, back to the drive electrode film 23 as a drive signal.SELECTED DRAWING: Figure 2a 【課題】バックキャビティの容積を小さくすると、実質的な特性が劣化するという不都合を解消し、小型薄型のパッケージ実装に適した高感度・低雑音の圧電型ＭＥＭＳマイクロフォンを得る。【解決手段】振動板として、センス電極膜２２、センス用圧電膜２１ａ、ドライブ用圧電膜２１ｂ、リファレンス電極膜２６、ドライブ電極膜２３、サポート膜２５を設けると共に、センス電極膜２２から出力されたセンス信号を増幅する増幅回路２４を設け、この増幅回路２４で増幅した信号をドライブ信号としてドライブ電極膜２３に帰還させることにより、音響信号圧力による上記振動板の振動（振幅）を抑制する。【選択図】図２ａ