| 摘要 |
A radio receiving device for matching impedance of an antenna by using junction capacitance in accordance with voltage variation and a method therefor are provided to convert a voltage according to an RSSI(Received Signal Strength Indication) numerical value for optimum antenna impedance matching, and to adjust junction capacitance according to stepwise voltage variation by a variable capacitance diode(varactor), thereby regularly maintaining impedance matching of the antenna. An antenna receives an FM(Frequency Modulation) radio signal. A radio chip(11) receives the radio signal through an RF(Radio Frequency)-IN terminal(10). An RSSI unit(12) outputs a voltage where FM receive sensitivity is varied in a predetermined range according to impedance variation of a line antenna and directivity and reception power of the RF-IN terminal(10). An ADC(Analog to Digital Converter)(13) converts an analog voltage outputted from the RSSI unit(12) into a digital voltage. A DAC(Digital to Analog Converter)(14) stepwise separates the digital voltage, and converts the digital voltage into an analog voltage. A multiplexer(15) receives an analog voltage value to select and output a gain according to the stepwise varied voltage. A variable capacitance diode(varactor)(16) adjusts junction capacitance in an antenna matching unit according to the stepwise varied voltage, and matches impedance.
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