Acoustic galvanic isolator incorporating single insulated decoupled stacked bulk acoustic resonator with acoustically-resonant electrical insulator

• US 20070085447A1
• Filed: 10/18/2005
• Published: 04/19/2007
• Est. Priority Date: 10/18/2005
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies Wireless IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Larson, John
• Granted Patent: US 7,425,787 B2
• Time in Patent Office: Days
• US Class Current: 310/318
• CPC Class Codes: H03H 9/132 characterized by a particular shape
• CPC Class Codes: H03H 9/584 Coupled Resonator Filters [CFR]
• CPC Class Codes: H03H 9/587 Air-gaps
• CPC Class Codes: H04B 11/00 Transmission systems employing sonic, ultrasonic or infrasonic waves
• CPC Class Codes: H10N 30/40 with electrical input and electrical output, e.g. functioning as transformers

Abstract

Embodiments of the acoustic galvanic isolator comprise a carrier signal source, a modulator connected to receive an information signal and the carrier signal, a demodulator, and an electrically-isolating acoustic coupler connected between the modulator and the demodulator. The acoustic coupler comprises no more than one decoupled stacked bulk acoustic resonator (IDSBAR). An electrically-isolating acoustic coupler based on a single IDSBAR is physically small and is inexpensive to fabricate yet is capable of passing information signals having data rates in excess of 100 Mbit/s and has a substantial breakdown voltage between its inputs and its outputs.

Claims

1. An acoustic galvanic isolator, comprising:

a carrier signal source;

a modulator connected to receive an information signal and the carrier signal;

a demodulator; and

connected between the modulator and the demodulator, an electrically-isolating acoustic coupler comprising a single insulating decoupled stacked bulk acoustic resonator (IDSBAR), the IDSBAR comprising an acoustically-resonant electrical insulator.

2. The acoustic galvanic isolator of claim 1, in which:

the IDSBAR additionally comprises a first film bulk acoustic resonator (FBAR), a second FBAR, and a first acoustic decoupler and a second acoustic coupler between the FBARs; and

the acoustically-resonant electrical insulator comprises a quarter-wave layer of electrically-insulating material and is located between the first acoustic decoupler and the second acoustic coupler.

3. The acoustic galvanic isolator of claim 1, in which:

the acoustically-resonant electrical insulator is a first acoustically-resonant electrical insulator;

the IDSBAR additionally comprises a first film bulk acoustic resonator (FBAR), a second FBAR, and, between the FBARs, in order, the first acoustically-resonant electrical insulator, an acoustic decoupler and a second acoustically-resonant electrical insulator; and

each acoustically-resonant electrical insulator is a half-wave acoustically-resonant electrical insulator and comprises a half-wave layer of electrically-insulating material.

4. The acoustic galvanic isolator of claim 1, in which the acoustically-resonant electrical insulator comprises a layer of electrically-insulating material.

5. The acoustic galvanic isolator of claim 4, in which the electrically-insulating material comprises one of aluminum nitride and aluminum oxide.

6. The acoustic galvanic isolator of claim 1, in which:

the IDSBAR additionally comprises a first film bulk acoustic resonator (FBAR), a second FBAR, and an acoustic decoupler; and

the acoustically-resonant electrical insulator and the acoustic decoupler are juxtaposed between the FBARs.

7. The acoustic galvanic isolator of claim 6, in which the acoustically-resonant electrical insulator is matched in acoustic impedance to the FBARs.

8. The acoustic galvanic isolator of claim 6, in which the acoustically-resonant electrical insulator differs in acoustic impedance from the FBARs by less than one order of magnitude.

9. The acoustic galvanic isolator of claim 6, in which the acoustic decoupler comprises an acoustic decoupling layer comprising an acoustic decoupling material.

10. The acoustic galvanic isolator of claim 6, in which the acoustic decoupling material differs in acoustic impedance from the FBARs by about one order of magnitude.

11. The acoustic galvanic isolator of claim 6, in which the acoustic decoupler is electrically insulating.

12. The acoustic galvanic isolator of claim 6, in which the acoustic decoupler comprises an acoustic Bragg structure.

13. The acoustic galvanic isolator of claim 12, in which the acoustic Bragg structure comprises one or more low acoustic impedance Bragg elements interleaved with high acoustic impedance Bragg elements;

and at least one of the Bragg elements is electrically insulating.

14. The acoustic galvanic isolator of claim 12, in which the acoustic Bragg structure comprises one or more layers of crosslinked polyphenylene polymer interleaved with layers of silicon dioxide.

15. The acoustic galvanic isolator of claim 6, in which the IDSBAR additionally comprises an additional acoustically-resonant electrical insulator and an additional acoustic decoupler between the FBARs.

16. The acoustic galvanic isolator of claim 1, additionally comprising an additional acoustically-resonant electrical insulator.

17. A method for galvanically isolating an information signal, the method comprising:

providing an electrically-isolating acoustic coupler comprising no more a single insulating decoupled stacked bulk acoustic resonator (IDSBAR), the IDSBAR comprising an acoustically-resonant electrical insulator;

providing a carrier signal;

modulating the carrier signal with the information signal to form a modulated electrical signal;

acoustically coupling the modulated electrical signal through the electrically-isolating acoustic coupler; and

recovering the information signal from the modulated electrical signal acoustically coupled through the electrically-isolating acoustic coupler.

18. The method of claim 17, in which:

the IDSBAR additionally comprises a first film bulk acoustic resonator (FBAR), a second FBAR stacked on the first FBAR, and a first acoustic decoupler and a second acoustic coupler located between the FBARs; and

the acoustically-resonant electrical insulator comprises a quarter-wave layer of electrically-insulating material and is located between the first acoustic decoupler and the second acoustic coupler.

19. The method of claim 17, in which:

the acoustically-resonant electrical insulator is a first acoustically-resonant electrical insulator;

the IDSBAR additionally comprises a first film bulk acoustic resonator (FBAR), a second FBAR stacked on the first FBAR, and, between the FBARs, in order, the first acoustically-resonant electrical insulator, an acoustic decoupler and a second acoustically-resonant electrical insulator; and

each acoustically-resonant electrical insulator is a half-wave acoustically-resonant electrical insulator and comprises a half-wave layer of electrically-insulating material.

20. The method of claim 17, in which the acoustically-resonant electrical insulator comprises a layer of electrically-insulating material.

21. The method of claim 20, in which the electrically-insulating material comprises one of aluminum nitride or aluminum oxide.

22. The method of claim 17, in which:

the IDSBAR additionally comprises a first film bulk acoustic resonator (FBAR), a second FBAR and an acoustic decoupler;

the acoustically-resonant electrical insulator and the acoustic decoupler are juxtaposed between the FBARs; and

the coupling comprises;

applying the modulated electrical signal to one of the FBARs, and

receiving the modulated electrical signal from the other of the FBARs.