公开(公告)号：EP1239585A4

公开(公告)日：2005-09-14

申请号：EP00978050

申请日：2000-12-01

申请人： YAMAHA CORP

发明人： MAEJIMA TOSHIO

IPC分类号： H03F3/30 ,  H03F3/45

CPC分类号： H03F3/45179 ,  H03F3/3028 ,  H03F3/45192 ,  H03F2203/45028 ,  H03F2203/45292 ,  H03F2203/45651

摘要： A differential amplifier circuit comprises an input circuit (10) for generating the difference in voltage between a positive input signal and a negative input signal; a feedback bias circuit (20) for providing a bias voltage corresponding to the differential voltage signal in response to the differential voltage signal supplied by the input circuit (10) and for feeding the output current back to control the bias voltage; an output circuit (30) for supplying load with the output current corresponding to the bias voltage; and a current detector circuit (40) for detecting the output current and supplying it to the feedback bias circuit (20). The differential amplifier circuit performs as a class-AB amplifier with the bias current value being close to zero if the differential voltage signal is zero.