Ladder-type filter, duplexer, and module

Patent metadata

Field	Value
Publication number	US-2016359470-A1
Application number	US-201615166631-A
Country	US
Kind code	A1
Filing date	May 27, 2016
Priority date	Jun 5, 2015
Publication date	Dec 8, 2016
Grant date	—

Abstract

A ladder-type filter includes: one or more series resonators connected in series between an input terminal and an output terminal; two or more parallel resonators connected in parallel between the input terminal and the output terminal; a first inductor connected in series between at least two nodes, each of the at least two nodes being located between a corresponding parallel resonator of at least two parallel resonators of the two or more parallel resonators and ground; and a first capacitor connected in series with the first inductor between the at least two nodes.

First claim

What is claimed is:

1 . A ladder-type filter comprising:
one or more series resonators connected in series between an input terminal and an output terminal; two or more parallel resonators connected in parallel between the input terminal and the output terminal; a first inductor connected in series between at least two nodes, each of the at least two nodes being located between a corresponding parallel resonator of at least two parallel resonators of the two or more parallel resonators and ground; and a first capacitor connected in series with the first inductor between the at least two nodes.

2 . The ladder-type filter according to claim 1 , further comprising:
a second inductor connected in series between at least one node of the at least two nodes and the ground; and a second capacitor connected in parallel to the second inductor between the at least one node and the ground.

3 . The ladder-type filter according to claim 2 , further comprising:
a third inductor connected in parallel to the second inductor and connected in series with the second capacitor between the at least one node and the ground.

4 . The ladder-type filter according to claim 1 , further comprising:
second inductors, each of the second inductors being connected in series between a corresponding node of the at least two nodes and the ground; and second capacitors, each of the second capacitors being connected in parallel to a corresponding second inductor of the second inductors between a corresponding node of the at least two nodes and the ground.

5 . The ladder-type filter according to claim 4 , further comprising:
third inductors, each of the third inductors being connected in parallel to a corresponding second inductor of the second inductors and connected in series with a corresponding second capacitor of the second capacitors between a corresponding node of the at least two nodes and the ground.

6 . The ladder-type filter according to claim 1 , further comprising:
a filter chip including the one or more series resonators and the two or more parallel resonators formed therein; and a substrate on which the filter chip is mounted, wherein at least one of the first inductor and the first capacitor is a chip component mounted on the substrate.

7 . The ladder-type filter according to claim 1 , further comprising:
a filter chip including the one or more series resonators and the two or more parallel resonators formed therein; and a substrate on which the filter chip is mounted, wherein at least one of the first inductor and the first capacitor is formed in the substrate.

8 . A ladder-type filter comprising:
one or more series resonators connected in series between an input terminal and an output terminal; two or more parallel resonators connected in parallel between the input terminal and the output terminal; a second inductor connected in series between at least one parallel resonator of the two or more parallel resonators and ground; a second capacitor connected in parallel to the second inductor between the at least one parallel resonator and the ground; and a third inductor connected in parallel to the second inductor and connected in series with the second capacitor between the at least one parallel resonator and the ground.

9 . A duplexer comprising:
a transmit filter connected between a transmit terminal and a common terminal; and a receive filter connected between a receive terminal and the common terminal, wherein at least one of the transmit filter and the receive filter is the ladder-type filter according to claim 1 .

10 . A duplexer comprising:
a transmit filter connected between a transmit terminal and a common terminal; and a receive filter connected between a receive terminal and the common terminal, wherein at least one of the transmit filter and the receive filter is the ladder-type filter according to claim 8 .

11 . A module comprising:
a ladder-type filter comprising:
one or more series resonators connected in series between an input terminal and an output terminal;
two or more parallel resonators connected in parallel between the input terminal and the output terminal;
a first inductor connected in series between at least two nodes, each of the at least two nodes being located between a corresponding parallel resonator of at least two parallel resonators of the two or more parallel resonators and ground; and
a first capacitor connected in series with the first inductor between the at least two nodes.

12 . A module comprising:
the ladder-type filter according to claim 8 .

Assignees

• Taiyo Yuden Kk

Inventors

• Kuwahara Eiji
• Endo Yuki

Classifications

• H03H9/605

  consisting of a ladder configuration · CPC title

• H03H7/1783

  Combined LC in series path · CPC title

• H03H9/6483

  Ladder SAW filters · CPC title

• H03H9/706

  Duplexers · CPC title

• H03H7/1775

  Parallel LC in shunt or branch path (H03H7/1791 takes precedence) · CPC title