LADDER FILTER, BRANCHING FILTER, AND COMMUNICATION APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a ladder filter which has transmission characteristics such as a passband improved, provide a branching filter using the same, and further provide a communication apparatus having them mounted thereon. SOLUTION: In a ladder filter 1, serial resonators S1, S2 and parallel resonators P1 to P3 are alternately connected. An inductor Lp is connected to the serial resonator S1 in parallel, and no inductor is connected to the serial resonator S2. When the resonance frequency of the serial resonator S1 is defined as fsr1 and the resonance frequency of the serial resonator S2 fsr2, a relationship of fsr1