DIELECTRIC FILTER AND DUPLEXER DIELECTRIC FILTER

摘要

PURPOSE: A dielectric filter and a duplexer dielectric filter are provided to obtain a frequency characteristic having a steep slope in a transition band, while reducing insertion losses. CONSTITUTION: A dielectric filter comprises a first elliptic function filter(10) including an input terminal oscillator(#1) coupled to an input terminal for a signal input, a first intermediate oscillator(#2) coupled to the input terminal oscillator, and a first parametric oscillator(#4-1) coupled to the first intermediate oscillator and negative-coupled to the input terminal oscillator; and a second elliptic function filter(20) including a second parametric oscillator(#4-2) coupled to the first parametric oscillator, a second intermediate oscillator(#2) coupled to the second parametric oscillator, and an output terminal oscillator(#3) coupled to the second intermediate oscillator and negative-coupled to the second parametric oscillator.