Differential filters with common mode rejection and broadband rejection

• US 6,600,390 B2
• Filed: 12/13/2001
• Issued: 07/29/2003
• Est. Priority Date: 12/13/2001
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Frank, Michael Louis
• Primary Examiner(s): Summons, Barbara
• Application Number:
  US10/017,605
• Publication Number:
  US 20030112098A1
• Time in Patent Office: 593 Days
• Field of Search: 333/186-196, 310/313.R, 310/313.B, 310/313.C, 310/313.D
• US Class Current: 333/189
• CPC Class Codes: H03H 9/0028 using surface acoustic wave devices
• CPC Class Codes: H03H 9/0095 using bulk acoustic wave devices
• CPC Class Codes: H03H 9/6483 Ladder SAW filters

Abstract

A differential filter includes a first input, a second input, a first output, a second output, and a plurality of acoustic resonator elements. The plurality of acoustic resonator elements is connected to the first input, the second input, the first output and the second output. The acoustic resonator elements are arranged to form at least two of a lattice structure, a full ladder structure and a paired half ladder structure.

Claims

1. A differential filter comprising:

a first input;

a second input;

a first output;

a second output; and

,

a plurality of acoustic resonator elements, coupled to the first input, the second input, the first output and the second output, the acoustic resonator elements being arranged to form both a lattice structure and a full ladder structure.

2. A differential filter as in claim 1 additionally comprising a reference voltage input coupled to the plurality of acoustic resonator elements, wherein the acoustic resonator elements are additionally arranged to form a paired half ladder structure.

3. A differential filter as in claim 1 wherein each of the acoustic resonator elements is a film bulk acoustic resonator (FBAR).

4. A differential filter as in claim 1 wherein each of the acoustic resonator elements is a surface acoustic wave (SAW) element.

5. A differential filter as in claim 1 additionally comprising a reference voltage input coupled to the plurality of acoustic resonator elements, wherein the acoustic resonator elements are additionally arranged to form a paired half ladder structure, the plurality of acoustic resonator elements including:

a first acoustic resonator element connected between the first input and a first node;

a second acoustic resonator element connected between the first input and the second node;

a third acoustic resonator element connected between the second input and the first node;

a fourth acoustic resonator element connected between the second input and the second node;

a fifth acoustic resonator element connected between the first node and the second node;

a sixth acoustic resonator element connected between the first output and the first node;

a seventh acoustic resonator element connected between the second output and the second node;

an eighth acoustic resonator element connected between the first output and the reference voltage input; and

,

a ninth acoustic resonator element connected between the second output and the reference voltage input.

6. A differential filter as in claim 1 additionally comprising a reference voltage input coupled to the plurality of acoustic resonator elements, wherein the acoustic resonator elements are additionally arranged to form a paired half ladder structure, the plurality of acoustic resonator elements including:

a first acoustic resonator element connected between the first input and a first node;

a second acoustic resonator element connected between the first input and the second node;

a third acoustic resonator element connected between the second input and the first node;

a fourth acoustic resonator element connected between the second input and the second node;

a fifth acoustic resonator element connected between the first node and the second node;

a sixth acoustic resonator element connected between the first node and a third node;

a seventh acoustic resonator element connected between the second node and a fourth node;

an eighth acoustic resonator element connected between the third node and the fourth node;

a ninth acoustic resonator element connected between the first output and the third node;

a tenth acoustic resonator element connected between the second output and the fourth node;

an eleventh acoustic resonator element connected between the first output and the reference voltage input; and

,

a twelfth acoustic resonator element connected between the second output and the reference voltage input.

7. A differential filter as in claim 1 wherein the plurality of acoustic resonator elements include:

a first acoustic resonator element connected between the first input and a first node;

a second acoustic resonator element connected between the first input and the second node;

a third acoustic resonator element connected between the second input and the first node;

a fourth acoustic resonator element connected between the second input and the second node;

a fifth acoustic resonator element connected between the first node and the second node;

a sixth acoustic resonator element connected between the first output and the first node; and

,

a seventh acoustic resonator element connected between the second output and the second node.

8. A differential filter as in claim 1 wherein the plurality of acoustic resonator elements include:

a first acoustic resonator element connected between the first input and a first node;

a second acoustic resonator element connected between the first input and the second node;

a third acoustic resonator element connected between the second input and the first node;

a fourth acoustic resonator element connected between the second input and the second node;

a fifth acoustic resonator element connected between the first node and the second node;

a sixth acoustic resonator element connected between the first node and a third node;

a seventh acoustic resonator element connected between the second node and a fourth node;

an eighth acoustic resonator element connected between the third node and the fourth node;

a ninth acoustic resonator element connected between the first output and the third node; and

,

a tenth acoustic resonator element connected between the second output and the fourth node.

9. A differential filter comprising:

a first input;

a second input;

a reference voltage input;

a first output;

a second output; and

,

a plurality of acoustic resonator elements, coupled to the first input, the second input, the first output and the second output, the acoustic resonator elements being arranged to form both a lattice structure and a paired half ladder structure.

10. A differential filter as in claim 9 wherein each of the acoustic resonator elements is a film bulk acoustic resonator (FBAR).

11. A differential filter as in claim 9 wherein each of the acoustic resonator elements is a surface acoustic wave (SAW) element.

12. A differential filter as in claim 9 wherein the plurality of acoustic resonator elements includes:

a first acoustic resonator element connected between the first input and a first node;

a second acoustic resonator element connected between the first input and the second node;

a third acoustic resonator element connected between the second input and the first node;

a fourth acoustic resonator element connected between the second input and the second node;

a fifth acoustic resonator element connected between the first output and the first node;

a sixth acoustic resonator element connected between the second output and the second node;

a seventh acoustic resonator element connected between the first output and the reference voltage input; and

,

an eighth acoustic resonator element connected between the second output and the reference voltage input.

13. A differential filter as in claim 9 wherein the plurality of acoustic resonator elements includes:

a first acoustic resonator element connected between the first input and a first node;

a second acoustic resonator element connected between the first input and the second node;

a third acoustic resonator element connected between the second input and the first node;

a fourth acoustic resonator element connected between the second input and the second node;

a fifth acoustic resonator element connected between the first node and a third node;

a sixth acoustic resonator element connected between the second node and a fourth node;

a seventh acoustic resonator element connected between the third node and the reference voltage input node;

an eight acoustic resonator element connected between the fourth node and the reference voltage input node;

a ninth acoustic resonator element connected between the first output and the third node;

a tenth acoustic resonator element connected between the second output and the fourth node;

an eleventh acoustic resonator element connected between the first output and the reference voltage input; and

,

a twelfth acoustic resonator element connected between the second output and the reference voltage input.

14. A differential filter comprising:

a first node;

a second node;

a reference voltage input;

a first output;

a second output; and

,

a plurality of acoustic resonator elements, coupled to the first node, the second node, the first output and the second output, the acoustic resonator elements being arranged to form both a full ladder structure and a paired half ladder structure, wherein the plurality of acoustic resonator elements includes;

a first acoustic resonator element connected between the first node and the second node,

a second acoustic resonator element connected between the first node and a third node,

a third acoustic resonator element connected between the second node and a fourth node,

a fourth acoustic resonator element connected between the third node and the fourth node,

a fifth acoustic resonator element connected between the first output and the third node,

a sixth acoustic resonator element connected between the second output and the fourth node,

a seventh acoustic resonator element connected between the first output and the reference voltage input, and

an eighth acoustic resonator element connected between the second output and the reference voltage input.

15. A differential filter as in claim 14 wherein each of the acoustic resonator elements is a film bulk acoustic resonator (FBAR).

16. A differential filter as in claim 14 wherein each of the acoustic resonator elements is a surface acoustic wave (SAW) element.

17. A differential filter comprising:

a first node;

a second node;

a reference voltage input;

a first output;

a second output; and

,

a plurality of acoustic resonator elements, coupled to the first node, the second node, the first output and the second output, the acoustic resonator elements being arranged to form both a full ladder structure and a paired half ladder structure, wherein the first node is a first circuit input, the second node is a second circuit input, and the plurality of acoustic resonator elements includes;

a first acoustic resonator element connected between the first node and the second node,

a second acoustic resonator element connected between the first node and a third node,

a third acoustic resonator element connected between the second node and a fourth node,

a fourth acoustic resonator element connected between the third node and the fourth node,

a fifth acoustic resonator element connected between a fifth node and the third node,

a sixth acoustic resonator element connected between a sixth node and the fourth node,

a seventh acoustic resonator element connected between the fifth node and the reference voltage input,

an eighth acoustic resonator element connected between the sixth node and the reference voltage input,

a ninth acoustic resonator element connected between the fifth node and the first output,

a tenth acoustic resonator element connected between the sixth node and the second output,

an eleventh acoustic resonator element connected between the first output and the reference voltage input, and

a twelfth acoustic resonator element connected between the second output and the reference voltage input.

18. A differential filter as in claim 17 wherein each of the acoustic resonator elements is a film bulk acoustic resonator (FBAR).

19. A differential filter as in claim wherein each of the acoustic resonator elements is a surface acoustic wave (SAW) element.