| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To reduce cross modulation distortions of a semiconductor switch which switches the connection between the antenna of a portable telephone set and external equipment, while preventing the standby time from becoming short due to the increase in current consumption. <P>SOLUTION: When the external equipment 9 is connected to a terminal 62 of a connector 6 having a switch function, a switching detection part 23 detects the potential at a terminal 63 being pulled up via a resistor 8 and a control part 15 instructs a switching control part 21 to short-circuit a common terminal 31 and a NO terminal 33 of an antenna changeover switch 3. When the terminal 62 is made open, the common terminal 3 and an NC terminal 32 of the antenna changeover switch 3 are short-circuited in the reverse manner. In both cases, the control part 15 recognizes whether the portable telephone set 1 is in a standby mode or calling mode and instructs a voltage control part 22 for applying source voltage which is relatively low for the standby mode, and relatively high for the calling mode, to a power terminal 35 of the antenna changeover switch 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
