CROSS REFERENCE TO RELATED APPLICATION

The present application is based on and claims priority of Japanese Patent Application No. 2020-017319 filed on Feb. 4, 2020. The entire disclosure of the above-identified application, including the specification, drawings and claims is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to multiplexers, front end circuits, and communication devices.

BACKGROUND

In recent communication service, the width of a communication band is increased, and a plurality of communication bands are simultaneously used, in order to increase communication capacity and the speed of communication.

Japanese Unexamined Patent Application Publication No. 2006-128881 discloses a multiplexer that can demultiplex and multiplex radio frequency signals in two different communication bands. The multiplexer disclosed in Japanese Unexamined Patent Application Publication No. 2006-128881 includes an inductor-capacitor (LC) filter that includes an inductor and a capacitor. According to this, radio frequency (RF) signals in wide communication bands can be demultiplexed and multiplexed.

BRIEF SUMMARY

The Third Generation Partnership Project (3GPP) has recently defined simultaneous transfer of radio frequency signals in frequency bands of 5th Generation New Radio (5G NR) such as n77 (3300 MHz to 4200 MHz), n78 (3300 MHz to 3800 MHz), and n79 (4400 MHz to 5000 MHz). Furthermore, 3GPP has also defined new communication bands of 5G NR in which the transmission and reception bands are distant, such as n91 (the transmission band ranging from 832 MHz to 862 MHz, and the reception band ranging from 1427 MHz to 1432 MHz), n92 (the transmission band ranging from 832 MHz to 862 MHz, and the reception band ranging from 1432 MHz to 1517 MHz), n93 (the transmission band ranging from 880 MHz to 915 MHz, and the reception band ranging from 1427 MHz to 1432 MHz), and n94 (the transmission band ranging from 880 MHz to 915 MHz, and the reception band ranging from 1432 MHz to 1517 MHz). When signals in such communication bands of 5G NR and a communication band adjacent to such a communication band or between the transmission and reception bands of such a communication band are simultaneously transferred, a low-loss multiplexer is necessary which increases the isolation level while handling frequency gaps between the communication bands and the bandwidths of the communication bands.

In view of this, the present disclosure provides low-loss multiplexers, low-loss front end circuits, and low-loss communication devices that increase the isolation level by handling frequency gaps between communication bands and the bandwidths of the communication bands.

In order to provide such a multiplexer, a multiplexer according to an aspect of the present disclosure includes: a first acoustic wave filter connected to a common terminal, the first acoustic wave filter including an acoustic wave resonator; a second acoustic wave filter connected to the common terminal, the second acoustic wave filter including an acoustic wave resonator; and an inductor-capacitor (LC) filter connected to the common terminal, the LC filter including one or more inductors and one or more capacitors. A passband of the second acoustic wave filter is between a passband of the first acoustic wave filter and a passband of the LC filter, a frequency gap between the passband of the second acoustic wave filter and the passband of the LC filter is greater than a frequency gap between the passband of the first acoustic wave filter and the passband of the second acoustic wave filter, the passband of the first acoustic wave filter includes one of a transmission band or a reception band of a first communication band, the passband of the LC filter includes a remaining one of the transmission band or the reception band of the first communication band, and the passband of the second acoustic wave filter includes one of a transmission band or a reception band of a second communication band different from the first communication band.

According to the present disclosure, a low-loss multiplexer, a low-loss front end circuit, and a low-loss communication device that increases the isolation level while handling a frequency gap between communication bands and the bandwidths of the communication bands.

