Acoustic filters providing negative capacitance for use in multiplexers

Patent metadata

Field	Value
Publication number	US-12456965-B2
Application number	US-202118251249-A
Country	US
Kind code	B2
Filing date	Sep 23, 2021
Priority date	Nov 12, 2020
Publication date	Oct 28, 2025
Grant date	Oct 28, 2025

Abstract

An acoustic filter providing negative capacitance for use in multiplexers is provided that may include a first resonator and a second resonator. The second resonator may be a three terminal element that includes two sub-resonator elements having opposite polarities that are mechanically coupled such that as one sub-resonator expands, the other contracts. The second resonator may act as a negative capacitance element relative to the first resonator such that the second resonator provides cancelation at specific frequencies. This structure may further reduce the order of an N-multiplexer ladder network and reduce total insertion loss.

First claim

What is claimed is:

1. A multiplexer comprising:
an input;
a first acoustic filter comprising:
a first resonator element comprising:
a first terminal electrically coupled to the input; and
a second terminal, wherein the first resonator element is configured to pass a first frequency to the second terminal; and

a second resonator element comprising:
a first sub-resonator element having a first polarity, the first sub-resonator element having a seventh terminal electrically coupled to the first terminal; and
a second sub-resonator element having a second polarity opposite the first polarity, the second sub-resonator element mechanically coupled to the first sub-resonator element with a third terminal therebetween; and

a second acoustic filter comprising:
a third resonator element comprising:
a fourth terminal electrically coupled to the input; and
a fifth terminal, wherein the second resonator element is configured to cancel signal leakage at the first frequency at the fifth terminal; and

a fourth resonator element comprising
a third sub-resonator element having the first polarity, the third sub-resonator element having an eighth terminal electrically coupled to the fourth terminal; and
a fourth sub-resonator element having the second polarity, the fourth sub-resonator element mechanically coupled to the third sub-resonator with a sixth terminal therebetween;

wherein the fourth sub-resonator element is electrically coupled to the second terminal through a ninth terminal and the second sub-resonator element is electrically coupled to the fifth terminal through a tenth terminal.

2. The multiplexer of claim 1 , wherein the first resonator element and the third resonator element also have the first polarity.

3. The multiplexer of claim 1 , further comprising a capacitor coupled to the third terminal.

4. The multiplexer of claim 1 , wherein the first acoustic filter further comprises a fifth resonator element.

5. The multiplexer of claim 4 , wherein the fifth resonator element comprises: a fifth sub-resonator element having the first polarity; and a sixth sub-resonator element having the second polarity, the sixth sub-resonator element mechanically coupled to the fifth sub-resonator.

6. The multiplexer of claim 5 , further comprising a third acoustic filter coupled to the input and wherein the sixth sub-resonator element is coupled to the third acoustic filter.

7. The multiplexer of claim 5 , further comprising a capacitor coupled to the first and second sub-resonator elements.

8. The multiplexer of claim 1 , further comprising a fifth resonator element serially coupled to the second terminal.

9. The multiplexer of claim 1 , further comprising a first output capacitor and a second output capacitor coupled to the second sub-resonator element.

10. The multiplexer of claim 1 , wherein the second acoustic filter further comprises a fifth sub-resonator element mechanically coupled to the third sub-resonator element.

11. A multiplexer comprising:
an input;
a first acoustic filter comprising:
a first resonator element comprising:
a first terminal electrically coupled to the input; and
a second terminal; and

a second resonator element comprising:
a first sub-resonator element having a first polarity, the first sub-resonator element having a seventh terminal electrically coupled to the first terminal; and
a second sub-resonator element having a second polarity opposite the first polarity, the second sub-resonator element mechanically coupled to the first sub-resonator element with a third terminal therebetween and a capacitor coupled to the third terminal; and

a second acoustic filter comprising:
a third resonator element comprising:
a fourth terminal electrically coupled to the input; and
a fifth terminal; and

a fourth resonator element comprising
a third sub-resonator element having the first polarity, the third sub-resonator element having an eighth terminal electrically coupled to the fourth terminal; and
a fourth sub-resonator element having the second polarity, the fourth sub-resonator element mechanically coupled to the third sub-resonator with a sixth terminal therebetween;

wherein the fourth sub-resonator element is electrically coupled to the second terminal through a ninth terminal and the second sub-resonator element is electrically coupled to the fifth terminal through a tenth terminal.

12. A multiplexer comprising:
an input;
a first acoustic filter comprising:
a first resonator element comprising:
a first terminal electrically coupled to the input; and
a second terminal; and

a second resonator element comprising:
a first sub-resonator element having a first polarity, the first sub-resonator element having a seventh terminal electrically coupled to the first terminal; and
a second sub-resonator element having a second polarity opposite the first polarity, the second sub-resonator element mechanically coupled to the first sub-resonator element with a third terminal therebetween; and

a second acoustic filter comprising:
a third resonator element comprising:
a fourth terminal electrically coupled to the input; and
a fifth terminal; and

a fourth resonator element comprising
a third sub-resonator element having the first polarity, the third sub-resonator element having an eighth terminal electrically coupled to the fourth terminal; and
a fourth sub-resonator element having the second polarity, the fourth sub-resonator element mechanically coupled to the third sub-resonator with a sixth terminal therebetween;

wherein the fourth sub-resonator element is electrically coupled to the second terminal through a ninth terminal and the second sub-resonator element is electrically coupled to the fifth terminal through a tenth terminal; and
a first output capacitor and a second output capacitor coupled to the second sub-resonator element.

Assignees

• Qorvo Us Inc

Inventors

• Khlat Nadim

Classifications

• H03H9/605

  consisting of a ladder configuration · CPC title

• H03H9/542

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

• H03H9/205 Primary

  having multiple resonators (crystal tuning forks H03H9/21) · CPC title

• H03H9/60

  Electric coupling means therefor {(H03H9/0095 takes precedence)} · CPC title

• H03H9/583

  comprising a plurality of piezoelectric layers acoustically coupled · CPC title