公开(公告)号：EP1192836A1

公开(公告)日：2002-04-03

申请号：EP01924304.7

申请日：2001-03-23

申请人： Microtronic Nederland B.V.

发明人： VAN HALTERAN, Aart, Z. ,  LAFORT, Adrianus, M.

IPC分类号： H04R3/00 ,  H04R25/00 ,  H04R21/02

CPC分类号： H04R25/00 ,  H04R1/04 ,  H04R3/04 ,  H04R19/016 ,  H04R2225/61 ,  H04R2410/01

摘要： A variable sensitivity/variable gain circuit for an electret microphone (10) having an amplifier (12) includes a sensitivity selecting circuit (32) coupled with the buffer amplifier (12) for adjusting the transduction gain of the microphone.

公开(公告)号：EP1285492A1

公开(公告)日：2003-02-26

申请号：EP01935795.3

申请日：2001-05-21

申请人： Microtronic Nederland B.V.

发明人： LAFORT, Adrianus, M.

IPC分类号： H03B1/00

CPC分类号： H03F3/185 ,  G05F3/205 ,  H03F1/301

摘要： A high input impedance circuit for a buffer amplifier of a hearing aid microphone includes a transistor (30) coupled across an input of the buffer amplifier and providing a high impedance transconductance, and a control circuit (32) operatively coupled with the transistor to control the effective value of the input impedance provided thereby.