Acoustic filters with improved return loss

Patent metadata

Field	Value
Publication number	US-12500567-B2
Application number	US-202318387679-A
Country	US
Kind code	B2
Filing date	Nov 7, 2023
Priority date	Dec 7, 2022
Publication date	Dec 16, 2025
Grant date	Dec 16, 2025

Abstract

Embodiments of an acoustic filter are disclosed. In some embodiments, a bandpass filter is included in a passband signal path, the passband signal path is connected between a first terminal and a second terminal. A first bandstop filter is located in a first stopband signal path, the first stopband signal path connected at the first terminal. Additionally, a second bandstop filter is located in a second stopband signal path, the second stopband signal path is connected at the second terminal.

First claim

What is claimed is:

1 . An acoustic filter, comprising:
a bandpass filter in a passband signal path, the passband signal path connected between a first terminal and a second terminal, wherein the bandpass filter comprises at least one series resonator connected to at least one shunt resonator; a first bandstop filter in a first stopband signal path, the first stopband signal path connected at the first terminal, wherein the first bandstop filter comprises at least one series resonator connected to at least one shunt resonator; a second bandstop filter in a second stopband signal path, the second stopband signal path connected at the second terminal, wherein the second bandstop filter comprises at least one series resonator connected to at least one shunt resonator; wherein a frequency of the at least one series resonator of the bandpass filter is used as a frequency of the at least one shunt resonator of the first stopband filter and as a frequency of the at least one shunt resonator of the second bandstop filter; and wherein a frequency of the at least one shunt resonator of the bandpass filter is used as a frequency of the at least one series resonator of the first stopband filter and as a frequency of the at least one series resonator of the second bandstop filter.

2 . The acoustic filter of claim 1 , further comprising:
a first termination resistor connected between the first bandstop filter and a reference terminal; and a second termination resistor connected between the second bandstop filter and the reference terminal.

3 . The acoustic filter of claim 1 , wherein the first terminal is an input terminal and the second terminal is an output terminal.

4 . An acoustic filter, comprising:
at least one bandpass filter in a passband signal path, the passband signal path connected between a first terminal and a second terminal, wherein the at least one bandpass filter comprises at least one series resonator connected to at least one shunt resonator; at least one first bandstop filter in a first stopband signal path, the first stopband signal path connected at the first terminal, wherein the at least one the first bandstop filter comprises at least one series resonator connected to at least one shunt resonator; and at least one second bandstop filter in a second stopband signal path, the second stopband signal path connected at the second terminal, wherein the at least one second bandstop filter comprises at least one series resonator connected to at least one shunt resonator; wherein a frequency of the at least one series resonator of the at least one bandpass filter is used as a frequency of the at least one shunt resonator of the at least one first stopband filter and as a frequency of the at least one shunt resonator of the at least one second bandstop filter; and wherein a frequency of the at least one shunt resonator of the at least one bandpass filter is used as a frequency of the at least one series resonator of the at least one first stopband filter and as a frequency of the at least one series resonator of the at least one second bandstop filter.

5 . The acoustic filter of claim 4 , further comprising:
a first termination resistor connected between the first bandstop filter and a reference terminal; and a second termination resistor connected between the second bandstop filter and the reference terminal.

6 . The acoustic filter of claim 4 , wherein the first terminal is an input terminal and the second terminal is an output terminal.

7 . An acoustic filter, comprising:
a bandpass filter connected between a first terminal and a second terminal, the bandpass filter comprising a first acoustic resonator and a second acoustic resonator, the first acoustic resonator connected in shunt to the second acoustic resonator; a first bandstop filter connected at the first terminal, the first bandstop filter comprising a third acoustic resonator and a fourth acoustic resonator, the third acoustic resonator connected in shunt to the fourth acoustic resonator; and a second bandstop filter connected at the second terminal, the second bandstop filter comprising a fifth acoustic resonator and a sixth acoustic resonator, the fifth acoustic resonator connected in shunt to the sixth acoustic resonator.

8 . The acoustic filter of claim 7 , further comprising:
a first termination resistor connected between the third acoustic resonator and a reference terminal; and a second termination resistor connected between the fifth acoustic resonator and the reference terminal.

9 . The acoustic filter of claim 7 , wherein each of the first acoustic resonator, the second acoustic resonator, the third acoustic resonator, the fourth acoustic resonator, the fifth acoustic resonator, and the sixth acoustic resonator comprises a bulk acoustic resonator.

10 . The acoustic filter of claim 7 , wherein each of the first acoustic resonator, the second acoustic resonator, the third acoustic resonator, the fourth acoustic resonator, the fifth acoustic resonator, and the sixth acoustic resonator comprises a surface wave acoustic wave resonator.

11 . The acoustic filter of claim 7 , further comprising one or more impedance matching components.

12 . The acoustic filter of claim 11 , wherein the one or more impedance matching components each comprise an inductor, a capacitor, a resistor, or a transformer.

13 . The acoustic filter of claim 7 , wherein the first terminal is an input terminal and the second terminal is an output terminal.

14 . The acoustic filter of claim 7 , wherein:
the bandpass filter further comprises at least one additional acoustic resonator; the first bandstop filter further comprises at least one additional acoustic resonator; or the second bandstop filter further comprises at least one additional acoustic resonator.

15 . An acoustic filter, comprising:
a bandpass filter connected between a first terminal and a second terminal, the bandpass filter comprising a first acoustic resonator and a second acoustic resonator, the second acoustic resonator connected between a first terminal of the first acoustic resonator and a reference terminal; a first bandstop filter connected at the first terminal, the first bandstop filter comprising a third acoustic resonator and a fourth acoustic resonator, the fourth acoustic resonator connected between a second terminal of the third acoustic resonator and the reference terminal; and a second bandstop filter connected at the second terminal, the second bandstop filter comprising a fifth acoustic resonator and a sixth acoustic resonator, the sixth acoustic resonator connected between a third terminal of the fifth acoustic resonator and the reference terminal.

16 . The acoustic filter of claim 15 , further comprising:
a first termination resistor connected between a fourth terminal of the third acoustic resonator and the reference terminal; and a second termination resistor connected between a fifth terminal of the fifth acoustic resonator and the reference terminal.

17 . The acoustic filter of claim 15 , wherein each of the first acoustic resonator, the second acoustic resonator, the third acoustic resonator, the fourth acoustic resonator, the fifth acoustic resonator, and the sixth acoustic resonator comprises a bulk acoustic resonator.

18 . The acoustic filter of claim 15 , wherein each of the first acoustic resonator, the second acoustic resonator, the third acoustic resonator, the fourth acoustic resonator, the fifth acoustic resonator, and the sixth acoustic resonator compris

Assignees

• Qorvo Us Inc

Inventors

• Lear Kelly M
• Klemmer Nikolaus
• Galipeau Jeffery
• Levesque Chris

Classifications

• H03H9/605

  consisting of a ladder configuration · CPC title

• H03H9/542 Primary

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

• H03H9/568

  consisting of a ladder configuration · CPC title

• H03H9/6483

  Ladder SAW filters · CPC title

• H03H9/547

  Notch filters, e.g. notch BAW or thin film resonator filters · CPC title