Multiplexer with acoustic assisted trap circuit

Patent metadata

Field	Value
Publication number	US-2025167766-A1
Application number	US-202519034327-A
Country	US
Kind code	A1
Filing date	Jan 22, 2025
Priority date	Jun 30, 2021
Publication date	May 22, 2025
Grant date	—

Abstract

Aspects of this disclosure relate to a multiplexer with an acoustic assisted trap circuit. The multiplexer includes an acoustic wave filter with an acoustic wave resonator and an impedance network that together provide a trap for a harmonic associated with another acoustic wave filter of the multiplexer. The acoustic wave filter can have an edge of a passband that is farther from the harmonic than other acoustic filters of the multiplexer.

First claim

What is claimed is:

1 . A multiplexer comprising:
a transmit filter including a first acoustic wave resonator; and a receive filter coupled to the transmit filter at a common node, the receive filter being associated with a different frequency band than the transmit filter, the receive filter including a second acoustic wave resonator and an impedance network, the second acoustic wave resonator and the impedance network being included in a trap circuit, and the trap circuit configured to provide a short circuit to ground at a frequency of a harmonic associated with the transmit filter.

2 . The multiplexer of claim 1 wherein the impedance network includes an inductor.

3 . The multiplexer of claim 2 wherein the second acoustic wave resonator is a shunt resonator in series with the inductor.

4 . The multiplexer of claim 3 wherein the impedance network consists of the inductor.

5 . The multiplexer of claim 3 wherein the receive filter includes a series acoustic wave resonator coupled between the second acoustic wave resonator and the common node.

6 . The multiplexer of claim 2 wherein the inductor is on a same die as the second acoustic wave resonator.

7 . The multiplexer of claim 1 wherein the second acoustic wave resonator is a surface acoustic wave resonator.

8 . The multiplexer of claim 7 wherein the first acoustic wave resonator is a bulk acoustic wave resonator.

9 . The multiplexer of claim 1 wherein the receive filter includes a multi-mode surface acoustic wave filter.

10 . The multiplexer of claim 1 further comprising a third filter and a fourth filter coupled to the common node, the third filter including a third acoustic wave resonator and a second impedance network included in a second trap circuit, the second trap circuit configured to provide a short circuit to ground at a frequency associated of a harmonic associated with the fourth filter.

11 . The multiplexer of claim 1 further comprising a plurality of acoustic wave filters coupled to the transmit filter and the receive filter at the common node, the receive filter being associated with a fundamental frequency that is farther from the harmonic than a respective fundamental frequency associated with any of the plurality of acoustic wave filters.

12 . The multiplexer of claim 1 wherein the harmonic is a second harmonic.

13 . The multiplexer of claim 1 wherein the multiplexer is included in a radio frequency system that achieves less than −90 dBc for the harmonic.

14 . A radio frequency system comprising:
a power amplifier; an antenna switch; and a multiplexer including a first acoustic wave filter and a second acoustic wave filter, the first acoustic wave filter being in a signal path between the power amplifier and the antenna switch, the second acoustic wave filter including an acoustic wave resonator and an impedance network included in a trap circuit, the trap circuit configured to provide a short circuit at a frequency of a second harmonic associated with the first acoustic wave filter, and the radio frequency system having emissions of less than- 90 dBc for the second harmonic associated with the first acoustic wave filter.

15 . The radio frequency system of claim 14 further comprising a low noise amplifier, the second acoustic wave filter being in a signal path between the low noise amplifier and the antenna switch.

16 . The radio frequency system of claim 15 wherein the first acoustic wave filter is associated with a different frequency band than the second acoustic wave filter.

17 . The radio frequency system of claim 14 wherein the multiplexer includes one or more additional acoustic wave filters, and the second acoustic wave filter having an edge of a passband that is farther from the second harmonic associated with the first acoustic wave filter than any other filter of the one or more additional acoustic wave filters.

18 . The radio frequency system of claim 14 wherein the first acoustic wave filter includes a bulk acoustic wave resonator, and the acoustic wave resonator is a surface acoustic wave resonator.

19 . The radio frequency system of claim 14 wherein the second acoustic wave filter includes a multi-mode surface acoustic wave filter.

20 . A method of radio frequency filtering, the method comprising:
filtering a radio frequency signal with a first acoustic wave filter of a multiplexer, the multiplexer also including a second acoustic wave filter, the first acoustic wave filter being a transmit filter, the second acoustic wave filter being a receive filter, and the first acoustic wave filter being associated with a different frequency band than the second acoustic wave filter; and while performing said filtering, providing a short circuit to ground at a frequency of a harmonic associated with the first acoustic wave filter with a trap circuit, the trap circuit including an acoustic wave resonator of the second acoustic wave filter and an inductor of the second acoustic wave filter.

Assignees

• Skyworks Solutions Inc

Inventors

• Chen Li
• Li Xianyi
• Shen Zhi
• Jin Renfeng

Classifications

• H03H9/72

  Networks using surface acoustic waves · CPC title

• H03H9/6483

  Ladder SAW filters · CPC title

• H03H9/70

  Multiple-port networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source · CPC title

• H04B1/40 Primary

  Circuits · CPC title

• H03H9/542

  including passive elements (H03H9/545 takes precedence) · CPC title