| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a transmission/reception circuit and a wireless communication device which can make a circuit scale small, can extensively reduce a circuit loss, and can operate in a wide band. <P>SOLUTION: The wireless communication devices each has a pass band different from each other, and includes a plurality of reception filters which filter wireless signals received by a reception antenna, a switch SW2 which selects one of the wireless signals from among the wireless signals outputted from a plurality of reception filters, and a low noise amplifier which amplifies a low noise of the wireless signal outputted from the switch SW2. An antenna impedance adjusting portion is connected to a feeding point of the reception antenna, and adjusts an antenna impedance so as to make an antenna impedance substantially minimum in a pass bandwidth of a reception filter selected when the received antenna is observed at the feeding point according to the selection of the wireless signal by the switch SW2 and to be coincident with an input/output impedance of a reception filter selected and an input impedance of the low noise amplifier. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
