Resonator type surface acoustic wave ladder filter with voltage variable capacitance element

摘要

To realizing a filter which is capable of properly controlling the passband, and the attenuation pole of a surface acoustic wave filter, a surface acoustic wave filter connected in a ladder type with the surface acoustic wave resonators 104, 105 has an element 106 which changes in capacity by voltage to be impressed and is connected in series with a resonator 105 connected in parallel to the signal line 100.