Acoustic galvanic isolator incorporating series-connected decoupled stacked bulk acoustic resonators

• US 7,737,807 B2
• Filed: 10/18/2005
• Issued: 06/15/2010
• 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 D III, Hardcastle, Ian
• Primary Examiner(s): Summons; Barbara
• Application Number:
  US11/253,444
• Publication Number:
  US 20070086080A1
• Time in Patent Office: 1,701 Days
• Field of Search: 333/187, 333/189, 310/311, 310/318, 310/319, 310/326, 310/327, 310/328
• US Class Current: 333/189
• 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: H03H 9/60 Electric coupling means therefor H03H9/0095 takes precedence

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 electrically-isolating acoustic coupler comprises series-connected decoupled stacked bulk acoustic resonators (DSBARs).

Claims

1. A 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 first decoupled stacked bulk acoustic resonator (DSBAR) comprising an acoustically-resonant electrical insulator, and a second DSBAR comprising acoustically-resonant electrical insulator, each of the DSBARs further comprising;

a first film bulk acoustic resonator (FBAR);

a second FBAR and an acoustic decoupler between the first FBAR and the second FBAR, wherein the DSBARs are connected in series; and

each of the DSBARs further comprises an additional acoustic decoupler between the FBARs; and

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

2. The galvanic isolator of claim 1, in which an electrical circuit connects the first FBAR of the first DSBAR to the modulator and the first FBAR of the second DSBAR to the demodulator.

3. The galvanic isolator of claim 2, in which the electrical circuit connects the second FBARs of the DSBARs in parallel to connect the DSBARs in series.

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

each of the FBARs comprises an opposed pair of electrodes and a piezoelectric element between the electrodes; and

the electrical circuit comprises;

a first electrical connection between a first one of the electrodes of the second FBAR of the first DSBAR and a first one of the electrodes of the second FBAR of the second DSBAR, and a second electrical connection between a second one of the electrodes of the second FBAR of the first DSBAR and a second one of the electrodes of the second FBAR of the second DSBAR, the second ones of the electrodes being closer to the acoustic decouplers of the DSBARs than the first ones of the electrodes.

5. The galvanic isolator of claim 2, in which the electrical circuit connects the second FBARs of the DSBARs in anti-parallel to connect the DSBARs in series.

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

each of the FBARs comprises an opposed pair of electrodes and a piezoelectric element between the electrodes; and

the electrical circuit comprises;

a first electrical connection between a first one of the electrodes of the second FBAR of the first DSBAR and a second one of the electrodes of the second FBAR of the second DSBAR, and a second electrical connection between a second one of the electrodes of the second FBAR of the first DSBAR and a first one of the electrodes of the second FBAR of the second DSBAR, the second ones of the electrodes being closer to the acoustic decouplers of the DSBARs than the first ones of the electrodes.

7. The galvanic isolator of claim 1, in which the acoustically-resonant electrical insulator comprises a layer of electrically-insulating material differing in acoustic impedance from the FBARs by less than one order of magnitude.

8. The galvanic isolator of claim 1, in which the acoustically-resonant electrical insulator comprises a layer of electrically-insulating material matched in acoustic impedance with the FBARs.

9. A 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 first decoupled stacked bulk acoustic resonator (DSBAR) and a second DSBAR connected in series to the first DSBAR, each of the DSBARs comprising;

a first film bulk acoustic resonator (FBAR), a second FBAR, and an acoustic decoupler between the first FBAR and the second FBAR, and an acoustically-resonant electrical insulator comprising a first half-wave acoustically-resonant electrical insulator, and a second half-wave acoustically-resonant electrical insulator, wherein the acoustic decoupler is located between the first half-wave acoustically-resonant electrical insulator and the second half-wave acoustically-resonant electrical insulator.

10. The galvanic isolator of claim 9, in which each of the half-wave acoustically-resonant electrical insulator comprises a half-wave layer of electrically-insulating material.