公开(公告)号：EP0109795A3

公开(公告)日：1984-08-08

申请号：EP83306737

申请日：1983-11-04

申请人： PICO PRODUCTS, INC.

发明人： Petrus, Peter R. ,  St. Louis, Raymond F.

IPC分类号： H03H07/07 ,  H03H07/12 ,  H04N07/16

CPC分类号： H04N7/17363 ,  H03H7/01 ,  H03H7/1708 ,  H03H7/175 ,  H03H7/1775 ,  H04N7/166

摘要： A filter for use in a cable television system for filtering out a given channel comprising a two pole filter, said filter including one pole which is fixed at the center frequency to be tuned out and a second variable pole responsive to an input voltage, the second pole adapted to vary in frequency about the first pole.

公开(公告)号：EP0203343A3

公开(公告)日：1988-06-01

申请号：EP86105314

申请日：1986-04-17

申请人： MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.

发明人： Ishikawa, Takayoshi ,  Yoshida, Yasuhiko

IPC分类号： H03H07/01 ,  H03H07/07

CPC分类号： H03H7/1791 ,  H03H7/065 ,  H03H7/07 ,  H03H7/075 ,  H03H7/1775

摘要： In a bridge T type trap circuit having CR delta :onnection circuit and a varible LC tank circuit, the CR delta connection circuit is connected to the LC ank circuit via a variable inductor (19; 31, 33; 40). In one embodiment, a capacitor (18) is coupled with he variable inductor (19; 31, 33) to form another LC ank circuit. In another embodiment, a variable inductor (39) used in the first-mentioned LC tank circuit has a tap which is grounded. Impedance values of the first-mentioned LC tank circuit and the variable nductor (40) are ajdusted so that absolute values of eal and imaginary parts thereof have given relationship. A resistor (22)of the CR delta connection circuit s used in common in a double-trap structure having wo CR delta conection circuits and two series cir- :uits each having two tank circuits.