| 摘要 |
<p>Sharp and high attenuation in the attenuation reneges close to each other outside the TV radio wave band and to provide a filter capable of suppressing the number of inductors used and contributing to miniaturization of a device. A plurality of elastic wave resonators connected in the form of parallel arms for forming a plurality of attenuation ranges are connected to the same-potential points of a signal path without any inductor. Alternatively, series circuits of a plurality of element sections which cause series resonance are connected to the signal path as the parallel arms. Thus, high attenuation can be achieved in each of the attenuation ranges. However, ranges equivalent to, as it were, zero points exist between the adjacent poles. However, even if the zero points exist, a characteristic of sharply attenuating both sides of each zero point can be achieved. Pairs of the elastic wave resonators (pairs of resonators) connected to the same potential points or the parallel arms consisting of the series circuits are connected to the signal path and inductors for inverting the phases are interposed between the arms.</p> |
