FILTER, DEMULTIPLEXER, AND MODULE INCLUDING DEMULTIPLEXER, COMMUNICATION APPARATUS

摘要

A demultiplexer (10) comprises a transmission filter (1) having a common terminal (Ant), a transmission terminal (Tx), and a reception terminal (Rx) and connected between the common terminal (Ant) and the transmission terminal (Tx); a reception filter (2) connected between the common terminal (Ant) and the reception terminal (Rx); and a phase shift circuit (3) connected in series with the reception filter (2), between the common terminal (Ant) and the reception terminal (Rx). A part of the line leading from the phase shift circuit (3) to the common terminal (Ant) or the transmission terminal (Tx) is coupled with a part of the line leading from the phase shift circuit (3) to the reception terminal (Rx) through a reactance. Consequently, arrival of a transmission signal from the transmission filter to a reception circuit is reduced or uprooted and isolation can be enhanced.