Portable radio terminal, antenna selector control method for use in portable radio terminal, and antenna selector control program

1. A portable radio terminal, comprising:

a transmitter that generates a transmission signal;

a plurality of antennas that radiate a radio wave corresponding to the transmission signal;

a voltage converter controller; and

an antenna selector that selects one of the plurality of antennas according to an antenna selection signal,

the antenna selector comprising:

a voltage converter that converts a power-supply voltage to a predetermined output voltage higher than the power-supply voltage; and

an analog switch circuit that operates with the predetermined output voltage from the voltage converter or the power-supply voltage being applied thereto, and

the voltage converter controller controlling the voltage converter to operate/halt according to a power level of the transmission signal generated by the transmitter, and applying the predetermined output voltage to the analog switch circuit when the voltage converter is operating and applying the power-supply voltage to the analog switch circuit when the voltage converter is halted.

2. A portable radio terminal according to claim 1 , wherein the voltage converter controller causes the voltage converter to operate and applies the predetermined output voltage to the analog switch circuit when the transmission signal generated by the transmitter is a transmission power value equal to or greater than a predetermined threshold, and the voltage converter controller causes the voltage converter to halt and applies the power-supply voltage to the analog switch circuit when the transmission power value is smaller than the threshold.

3. A portable radio terminal according to claim 1 , wherein the voltage converter controller controls the voltage converter to operate/halt according to presence/absence of the transmission signal generated by the transmitter.

4. A portable radio terminal according to claim 1 , wherein the voltage converter controller variably controls the output voltage from the voltage converter according to a transmission power value of the transmission signal generated by the transmitter.

5. An operation control method for a voltage converter used in a portable radio terminal that includes a transmitter that generates a transmission signal, a plurality of antennas that radiate a radio wave corresponding to the transmission signal, and an antenna selector that selects one of the plurality of antennas according to an antenna selection signal, wherein said antenna selector includes a voltage converter that converts a power-supply voltage to a predetermined output voltage higher than the power-supply voltage and an analog switch circuit that operates with the predetermined output voltage from the voltage converter or the power-supply voltage being applied thereto; the method comprising:

controlling the voltage converter to operate/halt according to a power level of the transmission signal generated by the transmitter; and

applying the predetermined output voltage to the analog switch circuit when the voltage converter is operating and applying the power-supply voltage to the analog switch circuit when the voltage converter is halted.

6. An operation control method for a voltage converter according to claim 5 , wherein the voltage converter is operated to apply the predetermined output voltage to the analog switch circuit when the transmission signal generated by the transmitter is a transmission power value equal to or greater than a predetermined threshold, and the voltage converter is caused to halt to apply the power-supply voltage to the analog switch circuit when the transmission power value is smaller than the threshold.

7. An operation control method for a voltage converter according to claim 5 , wherein the voltage converter is controlled to operate/halt according to presence/absence of the transmission signal generated by the transmitter.

8. An operation control method for a voltage converter according to claim 5 , wherein the output voltage from the voltage converter is variably controlled according to a transmission power value of the transmission signal generated by the transmitter.

9. A control program product used in a portable radio terminal that includes a transmitter that generates a transmission signal, a plurality of antennas that radiate a radio wave corresponding to the transmission signal; a voltage converter controller; and an antenna selector that selects one of the plurality of antennas according to an antenna selection signal, the antenna selector including a voltage converter that converts a power-supply voltage to a predetermined output voltage higher than the power-supply voltage, and an analog switch circuit that operates with the predetermined output voltage from the voltage converter or the power-supply voltage being applied thereto, the computer program product comprising:

means for causing the voltage converter controller to provide control to cause the voltage converter to operate/halt according to a power level of the transmission signal generated by the transmitter; and

means for causing the voltage converter controller to apply the predetermined output voltage to the analog switch circuit when the voltage converter is operating and apply the power-supply voltage to the analog switch circuit when the voltage converter is halted.

10. A control method for selecting one of a plurality of antennas, comprising:

selecting one of said antennas in response to an antenna selection signal; and

controlling a voltage level which is applied to a switch for selecting antennas according to a power level of a transmission signal,

wherein said controlling is applying a predetermined high voltage to the switch in the case that the power level of the transmission signal is equal to or greater than the predetermined threshold and applying a predetermined low voltage to the switch in the case that the power level of the transmission signal is smaller than the predetermined threshold.