| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve an IMD (intermodulation distortion) characteristic in an analog switch circuit of an antenna switch provided in a portable radio terminal having two antennas or more, and to reduce power consumption. <P>SOLUTION: When the transmission power value of a transmission signal T generated in a transmitter 41 is a predetermined threshold or larger a controller 70 operates a voltage conversion circuit 62. As a result, an output voltage Va is applied to an antenna switch 61, and thus, intermodulation distortion in the antenna switch 61 can be improved. Also, when the transmission power value is smaller than the threshold, the controller 70 suspends the operation of the voltage conversion circuit 62. At this time, a semiconductor switch 63 is turned an on-state, and a power supply voltage Vc is applied to the antenna switch 61. Thus, as compared to the case of the output voltage Va of the voltage conversion circuit 62 being applied to the antenna switch 61, the power consumption is reduced. This produces a longer battery life, providing a longer standby time of a portable radio terminal. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
