公开(公告)号：US5175508A

公开(公告)日：1992-12-29

申请号：US802686

申请日：1991-12-05

申请人： Randal R. Gingrich ,  Nicholas L. Difiore ,  Max H. Behrens

发明人： Randal R. Gingrich ,  Nicholas L. Difiore ,  Max H. Behrens

IPC分类号： H03G1/00 ,  H03G11/00

CPC分类号： H03G1/007 ,  H03G11/00

摘要： A voltage-controlled amplifier employs an operational amplifier with negative feedback for setting the gain. A voltage variable resistance such as a junction-field-effect transistor (JFET) is employed as part of a variable voltage divider for controlling the amplifier gain. Resistors in series and in parallel with the JFET determine minimum and maximum resistances corresponding to upper and lower limits for the amplifier gain. Thus, multiple channels of an amplifier can be provided with closely matched characteristics even using separate JFETs in each separate channel which have unmatched characteristics.