| 摘要 |
PROBLEM TO BE SOLVED: To improve high-pass side cutoff characteristics of a band-pass filter applicable to a super-broadband radio system enabling high speed transmission. SOLUTION: The band-pass filter, used for a balancing circuit, comprises a dielectric 9, a pair of first lines arranged on a first surface of the dielectric symmetrically with each other with respect to a symmetrical plane C crossing with the first surface, and a pair of second lines 2, 2 arranged on a second surface of the dielectric symmetrically with each other with respect to the symmetrical plane. Line widths of the first lines and the second lines are increased at their opening ends 3, 6 wider than at their intermediate portions and decreased at their input/output ends 4, 5 than at their intermediate portions, thereby increasing a high-pass side cutoff frequency. This eliminates the need for a low-pass filter for improving the high-pass side cutoff characteristics. COPYRIGHT: (C)2009,JPO&INPIT
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