| 摘要 |
PROBLEM TO BE SOLVED: To execute simply and exactly the impedance matching of an antenna individually for every device without sacrificing an antenna gain in a receiver with a built-in antenna. SOLUTION: An impedance matching circuit 3 uses a variable capacity diode D. The amplitude of the reverse bias voltage applied to the variable capacity diode D can be set arbitrarily by a D/A converter 9. When the mode of operation is a regulation mode, while changing the reverse bias voltage generated from the D/A converter 9, the signal level of an RSSI signal is measured, and the input data of the D/A converter 9 are measured, and the input data of the D/A converter 9 when the measured result becomes the maximum are stored as regulating data in an EEPROM 13. The reverse bias voltage in response to the regulating data is applied to the variable capacity diode D by reading the regulating data stored in the EEPROM 13, and setting as the input data of the D/A converter 9. COPYRIGHT: (C)2006,JPO&NCIPI
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