| 摘要 |
<p>When first high frequency signals from an antenna input terminal are selected to be outputted, all transistors constituting first and second switch devices are turned off and a RF modulator is also turned off. Therefore, first high frequency signals are transmitted to a TV output terminal through a first transmission line. When second high frequency signals outputted from the RF modulator are selected to be outputted, the RF modulator is turned on and transistors constituting the first and second switch devices are turned on. Consequently, second high frequency signals are transmitted to the TV output terminal through a second transmission line. On this occasion, the transistors constituting the first switch grounds the first transmission line and form a parallel resonance circuit in the first transmission line. Therefore, the passage of the first high frequency signals from the antenna input terminal is cut off and the reverse passage of the second high frequency signals and a harmonics component thereof from the second transmission line is prevented.</p> |
