| 摘要 |
PURPOSE: An antenna matching device of a portable radio telephone is provided to perform an optimum antenna matching according to a casing state by varying a capacitance value. CONSTITUTION: An antenna matching device of a portable radio telephone comprises a folder sensor(20), a CPU(Central Processing Unit)(30), a DAC(Digital to Analog Converter)(40), and a matching circuit portion(50). The folder sensor(20) senses an opening state or a shutting state of a telephone casing. The CPU(30) controls a voltage according to the opening state or the shutting state of the telephone casing. The DAC(40) generates voltages of different sizes according to control voltages of the CPU(30). The matching circuit portion(50) performs an impedance matching between an antenna and a transceiver circuit portion(60) by controlling a capacitance value.
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