| 摘要 |
<P>PROBLEM TO BE SOLVED: To attenuate interfering wave without a trap and to adjust a signal level of a desired signal in a reception channel having an interference mode. <P>SOLUTION: An input tuning circuit 30 includes: inductors L1 and L2; a varactor diode VD1 constituting a tuning circuit with the inductors L1 and L2; an inductor L5 where a synthesized inductance value is set to be smaller than an inductance value of the inductors L1 and L2 in a state where it is connected to the inductors L1 and L2; and a transistor TR1. When a specified channel is received, the transistor TR1 connects the inductor L5 to the inductor L1. Fixed voltage is applied to the other end of the varactor diode VD1 and inter-terminal voltage equivalent to a difference with tuning voltage is generated. When a channel other than the specified channel is received, the inductor L5 is set to an open state and the fixed voltage is prevented from being applied to the other end of the varactor diode VD1. <P>COPYRIGHT: (C)2012,JPO&INPIT |
