Acoustic galvanic isolator incorporating single decoupled stacked bulk acoustic resonator

• US 20070090892A1
• Filed: 10/18/2005
• Published: 04/26/2007
• 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 7,675,390 B2
• Time in Patent Office: Days
• US Class Current: 333/24.2
• CPC Class Codes: H03H 9/584 Coupled Resonator Filters [CFR]
• CPC Class Codes: H03H 9/587 Air-gaps

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 (DSBAR). An electrically-isolating acoustic coupler based on a single DSBAR 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 no more than one decoupled stacked bulk acoustic resonator (DSBAR).

2. The acoustic galvanic isolator of claim 1, in which the DSBAR comprises a first film bulk acoustic resonator (FBAR), a second FBAR, and an electrically-insulating acoustic decoupler between the FBARs.

3. The acoustic galvanic isolator of claim 2, additionally comprising:

a first electrical circuit electrically connecting the modulator to the first FBAR; and

a second electrical circuit electrically connecting the demodulator to the second FBAR.

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

each FBAR comprises opposed planar electrodes and a piezoelectric element between the electrodes;

the first electrical circuit electrically connects the modulator to the electrodes of the first FBAR; and

the first electrical circuit electrically connects the electrodes of the second FBAR.

5. The acoustic galvanic isolator of claim 2, in which the electrically-insulating acoustic decoupler comprises a layer of electrically-insulating acoustic decoupling material.

6. The acoustic galvanic isolator of claim 5, in which:

the FBARs have an acoustic impedance;

the acoustic decoupling material has an acoustic impedance; and

the acoustic impedance of the acoustic decoupling material differs from the acoustic impedance of the FBARs by about one order of magnitude.

7. The acoustic galvanic isolator of claim 2, in which the electrically-insulating acoustic decoupler comprises an electrically-insulating acoustic Bragg structure.

8. The acoustic galvanic isolator of claim 7, in which the electrically-insulating acoustic Bragg structure comprises one or more low acoustic impedance Bragg elements interleaved with high acoustic impedance Bragg elements, at least one of the Bragg elements comprising a layer of electrically-insulating material.

9. The acoustic galvanic isolator of claim 7, in which the electrically-insulating acoustic Bragg structure comprises one or more electrically-insulating low acoustic impedance Bragg elements interleaved with electrically-insulating high acoustic impedance Bragg elements.

10. The acoustic galvanic isolator of claim 7, in which the acoustic Bragg structure comprises one or more layers of crosslinked polyphenylene polymer interleaved with layers of silicon dioxide.

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

providing an electrically-isolating acoustic coupler comprising no more than one decoupled stacked bulk acoustic resonator (DSBAR);

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.

12. The method of claim 11, in which:

the DSBAR comprises a first film bulk acoustic resonator (FBAR), a second FBAR, and an electrically-insulating acoustic decoupler between the FBARs; and

the passing comprises;

applying the modulated electrical signal to the first FBAR, and

receiving the modulated electrical signal from the second FBAR.

13. The method of claim 11, in which:

each FBAR comprises opposed planar electrodes and a piezoelectric element between the electrodes;

the applying comprises applying the modulated electrical signal to the electrodes of the first FBAR; and

the receiving comprises receiving the modulated electrical signal from the electrodes of the second FBAR.

14. The method of claim 11, in which the recovering comprises performing clock and data recovery on the modulated electrical signal acoustically coupled through the electrically-isolating acoustic coupler.

15. The method of claim 11, in which:

the DSBAR comprises a first film bulk acoustic resonator (FBAR), a second FBAR, and an acoustic decoupler between the FBARs; and

the acoustic decoupler comprises a layer of electrically-insulating acoustic decoupling material.

16. The method of claim 11, in which:

the DSBAR comprises a first film bulk acoustic resonator (FBAR), a second FBAR, and an acoustic decoupler between the FBARs; and

the acoustic decoupler comprises an electrically-insulating acoustic Bragg structure.

17. The method of claim 16, in which the electrically-insulating acoustic Bragg structure comprises one or more low acoustic impedance Bragg elements interleaved with high acoustic impedance Bragg elements, at least one of the Bragg elements comprising a layer of electrically-insulating material.

18. The method of claim 16, in which the electrically-insulating acoustic Bragg structure comprises one or more electrically-insulating low acoustic impedance Bragg elements interleaved with electrically-insulating high acoustic impedance Bragg elements.