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US-12620958-B2 - Multiplexer with hybrid acoustic passive filter

US12620958B2US 12620958 B2US12620958 B2US 12620958B2US-12620958-B2

Abstract

Aspects of this disclosure relate to a multiplexer with a hybrid acoustic passive filter. The multiplexer includes a plurality of filters configured to filter respective radio frequency signals, a shared filter coupled between each of the plurality of filters and a common node, and a radio frequency filter coupled to the common node. At least a first filter of the plurality of filters includes acoustic resonators and a non-acoustic passive component. Related multiplexers, wireless communication devices, and methods are disclosed.

Inventors

  • Hai H. Ta
  • Bo Pan
  • Weimin Sun

Assignees

  • SKYWORKS SOLUTIONS, INC.

Dates

Publication Date
20260505
Application Date
20230405

Claims (20)

  1. 1 . A multiplexer with a hybrid acoustic inductor-capacitor (LC) filter with harmonic suppression, the multiplexer comprising: a first filter including a hybrid passive/acoustic filter to filter a radio frequency signal and a non-acoustic LC filter configured to suppress a harmonic of the radio frequency signal, the non-acoustic LC filter cascaded with the hybrid passive/acoustic filter, and the hybrid passive/acoustic filter including a first acoustic resonator, a second acoustic resonator, an inductor, and a capacitor; and a second filter coupled to the first filter at a common node, the non-acoustic LC filter being coupled between the hybrid passive/acoustic filter and the common node.
  2. 2 . The multiplexer of claim 1 wherein the non-acoustic LC filter is a notch filter.
  3. 3 . The multiplexer of claim 1 wherein the non-acoustic LC filter is a low pass filter having a cutoff frequency above a passband of the hybrid passive/acoustic filter.
  4. 4 . The multiplexer of claim 1 wherein the hybrid passive/acoustic filter includes a second inductor, the first acoustic resonator is a shunt acoustic resonator in series with the inductor and in parallel with the second inductor.
  5. 5 . The multiplexer of claim 1 wherein the first and second acoustic resonators are shunt acoustic resonators, the inductor and the capacitor are in arranged parallel with each other as an LC tank, and the LC tank is in series between the first acoustic resonator and the second acoustic resonator.
  6. 6 . The multiplexer of claim 1 wherein the second filter includes a second hybrid passive/acoustic filter.
  7. 7 . The multiplexer of claim 6 wherein the second filter is a band pass filter having a passband from 3.3 gigahertz to 4.2 gigahertz.
  8. 8 . The multiplexer of claim 6 wherein the second filter is a band pass filter having a passband from 4.4 gigahertz to 5 gigahertz.
  9. 9 . The multiplexer of claim 1 wherein the first filter is a mid band filter and the second filter is a high band filter.
  10. 10 . The multiplexer of claim 9 further comprising a third filter coupled to the common node, the third filter being a low band filter.
  11. 11 . The multiplexer of claim 1 wherein the first acoustic resonator is a bulk acoustic wave resonator.
  12. 12 . A hybrid acoustic inductor-capacitor (LC) filter with harmonic suppression, the hybrid acoustic LC filter comprising: a hybrid passive/acoustic filter configured to filter a radio frequency signal, the hybrid passive/acoustic filter including a first acoustic resonator, a second acoustic resonator, a first inductor, a second inductor, and a capacitor; and a non-acoustic LC filter cascaded with the hybrid passive/acoustic filter, the non-acoustic LC filter configured to suppress a harmonic of the radio frequency signal.
  13. 13 . The hybrid acoustic LC filter of claim 12 wherein the non-acoustic LC filter is a notch filter.
  14. 14 . The hybrid acoustic LC filter of claim 12 wherein the hybrid passive/acoustic filter is a band pass filter having a passband, and the non-acoustic LC filter is a low pass filter having a cutoff frequency above the passband.
  15. 15 . The hybrid acoustic LC filter of claim 12 wherein the first acoustic resonator is a bulk acoustic wave resonator.
  16. 16 . The hybrid acoustic LC filter of claim 12 wherein the first inductor is a shunt inductor in series with the first inductor and in parallel with the second inductor.
  17. 17 . The hybrid acoustic LC filter of claim 12 wherein the first and second acoustic resonators are shunt acoustic resonators, the first inductor and the capacitor are arranged in parallel with each other as an LC tank, and the LC tank is in series between the first acoustic resonator and the second acoustic resonator.
  18. 18 . The hybrid acoustic LC filter of claim 12 wherein the first and second acoustic resonators are shunt acoustic resonators, and the first inductor is in series between the first acoustic resonator and the second acoustic resonator.
  19. 19 . The hybrid acoustic LC filter of claim 12 wherein the non-acoustic LC filter includes integrated passive devices of an integrated passive device die.
  20. 20 . A wireless communications device comprising: a radio frequency front end including a multiplexer, the multiplexer including a first filter and a second filter, the first filter including a hybrid passive/acoustic filter to filter a radio frequency signal and a non-acoustic inductor-capacitor (LC) filter configured to suppress a harmonic of the radio frequency signal, the second filter coupled to the first filter at a common node, the non-acoustic LC filter cascaded with the hybrid passive/acoustic filter, the non-acoustic LC filter being coupled between the hybrid passive/acoustic filter and the common node, and the hybrid passive/acoustic filter including a first acoustic resonator, a second acoustic resonator, an inductor, and a capacitor; an antenna in communication with the radio frequency front end, the antenna configured to transmit a filtered version of the radio frequency signal with the harmonic suppressed; a baseband processor; and a transceiver in communication with the radio frequency front end, the transceiver also in communication with the baseband processor.

Description

CROSS REFERENCE TO PRIORITY APPLICATIONS Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR § 1.57. This application is a continuation of U.S. patent application Ser. No. 17/646,657, filed Dec. 30, 2021 and titled “MULTIPLEXER WITH HYBRID ACOUSTIC PASSIVE FILTER,” which is a continuation of U.S. patent application Ser. No. 17/134,955, filed Dec. 28, 2020 and titled “HYBRID ACOUSTIC LC FILTER CASCADED WITH LC FILTER,” which is a continuation of U.S. patent application Ser. No. 16/514,857, filed Jul. 17, 2019 and titled “CASCADED FILTER CIRCUIT WITH HYBRID ACOUSTIC LC FILTER.” U.S. patent application Ser. No. 16/514,857 claims the benefit of priority under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 62/700,142, filed Jul. 18, 2018 and titled “HYBRID ACOUSTIC LC FILTER CASCADED WITH LC FILTER;” U.S. Provisional Patent Application No. 62/700,148, filed Jul. 18, 2018 and titled “PARALLEL HYBRID ACOUSTIC PASSIVE FILTER;” and U.S. Provisional Patent Application No. 62/700,146, filed Jul. 18, 2018 and titled “HYBRID ACOUSTIC LC FILTER WITH HARMONIC SUPPRESSION.” The disclosures of each of these priority applications are hereby incorporated by reference in their entireties herein. BACKGROUND Technical Field Embodiments of this disclosure relate to a hybrid acoustic LC filter. Description of Related Technology An acoustic wave filter can include a plurality of acoustic resonators arranged to filter a radio frequency signal. Acoustic resonators can be arranged as a ladder filter to filter the radio frequency signal. Example acoustic wave filters include surface acoustic wave (SAW) filters and bulk acoustic wave (BAW) filters. Acoustic wave filters can be implemented in radio frequency electronic systems. For instance, filters in a radio frequency front end of a mobile phone can include acoustic wave filters. An LC filter includes at least an inductor and a capacitor. LC filters are non-acoustic filters that include passive components. LC filters can filter radio frequency signals. Filtering relatively high frequency radio frequency signals and meeting stringent filtering specifications can be difficult. Accordingly, improved filters are desired to filter relatively high frequency signals and meet performance specifications. SUMMARY OF CERTAIN INVENTIVE ASPECTS The innovations described in the claims each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the claims, some prominent features of this disclosure will now be briefly described. One aspect of this disclosure is a cascaded filter for radio frequency filtering. The cascaded filter includes a hybrid acoustic LC filter and a non-acoustic LC filter cascaded with the hybrid acoustic LC filter. The hybrid acoustic LC filter is configured to filter a radio frequency signal. The hybrid acoustic LC filter includes a first acoustic resonator on an acoustic resonator die, a second acoustic resonator, a capacitor external to the acoustic resonator die, and an inductor external to the acoustic resonator die. The non-acoustic LC filter includes an LC circuit. The hybrid acoustic LC filter further can further include a second inductor in parallel with the second acoustic resonator, in which the second acoustic resonator is arranged as a shunt resonator in series with the inductor. The first acoustic resonator and the second acoustic resonator can be shunt resonators. The capacitor and the inductor can be arranged as an LC tank coupled between the first acoustic resonator and the second acoustic resonator. The first acoustic resonator can be coupled to a node in a signal path between the LC circuit and both the inductor and the capacitor. The first acoustic resonator and the second acoustic resonator can be bulk acoustic wave resonators. For example, the first acoustic resonator and the second acoustic resonator can be film bulk acoustic wave resonators. The LC circuit of the non-acoustic LC filter can include integrated passive devices on an integrated passive device die. The inductor of the hybrid acoustic LC filter can be a surface mount inductor. The inductor of the hybrid acoustic LC filter can include a conductive trace of a substrate. The integrated passive devices can include an LC shunt circuit and a series LC resonant circuit. The LC circuit of the non-acoustic LC filter can include a series LC resonant circuit and an LC shunt circuit. The series LC resonant circuit can include a parallel LC circuit. The LC shunt circuit can includes a series LC circuit. The LC circuit of the non-acoustic LC filter can further include a second shunt series LC circuit. A passband of the cascaded filter can be set by the non-acoustic LC filter. The first acoustic resonator can be arranged to provide rejection at a frequency band outside of t