| 摘要 |
PROBLEM TO BE SOLVED: To improve an out-band attenuation characteristic by suppressing coupling between a signal input and output when unbalanced terminals are connected using interdigital-coupled resonators. SOLUTION: A first resonator 1 and a second resonator 2 have pairs of interdigital-coupled quarter-wavelength resonators 11 and 12, and 21 and 22 respectively. The first and second resonators 1 and 2 each have a signal terminal 4A or 5A connected to one quarter-wavelength resonator 11 or 21 and also has a terminal 4B or 5A for ground connection connected to the other quarter-wavelength resonator 12 or 22 in a position rotation symmetric to a rotational symmetry axis C. The unbalanced terminals are composed of the terminals 4B and 5B for ground connection and signal terminals 4A and 5A to have a terminal structure similar to that of balanced terminals, so that coupling between the signal input and output when the unbalanced terminals are connected is suppressed more than when a conventional structure of unbalanced terminals is used, and an attenuation characteristic outside a passband is improved. COPYRIGHT: (C)2009,JPO&INPIT
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