SURFACE ACOUSTIC WAVE DEVICE

摘要

A band filter whose bandwidth and cutoff characteristic are freely set without requiring sophisticated design or adjustments. To provide such a filter, a surface acoustic wave device is composed of a main filter (Fm) and a subfilter (Fs) that are connected in parallel. The subfilter (Fs) has a frequency-attenuation characteristic that includes a stop band in the frequency range corresponding to the passband of the main filter (Fm), and the frequency-attenuation characteristic of the subfilter (Fs) includes a transition to its passband in the slope outside passband of the main filter (Fm), with the result that the phases of signals are opposite.