| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem of a conventional high frequency band pass filter that cannot eliminate a disturbance signal close to a desired signal because its 3 dB pass bandwidth is fixed. SOLUTION: The high frequency bandpass filter disclosed herein includes: a tuning circuit 24 connected between an input terminal 25 and ground; and a tuning circuit 28 with a resonance frequency nearly equal to that of the tuning circuit 24 and connected between an output terminal 29 and ground, wherein the input terminal 25 and the output terminal 29 are high-frequency-coupled by a variable capacitance diode 31, and a control voltage is applied to the variable capacitance diode 31 to control a 3 dB pass bandwidth 41 of the high frequency band pass filter 21. Thus, a disturbance signal existing in the vicinity of the pass bandwidth can be eliminated. COPYRIGHT: (C)2006,JPO&NCIPI
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