Acoustic galvanic isolator

• US 20070085632A1
• Filed: 10/18/2005
• Published: 04/19/2007
• Est. Priority Date: 10/18/2005
• Status: Abandoned Application

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Hardcastle, Ian, Larson, John
• Application Number:
  US11/253,464
• Publication Number:
  US 20070085632A1
• Time in Patent Office: Days
• US Class Current: 333/187
• 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 9/605 consisting of a ladder configuration

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. In an exemplary embodiment, the electrically-isolating acoustic coupler comprises film bulk acoustic resonators (FBARs). An electrically-isolating acoustic coupler 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

an electrically-isolating acoustic coupler connected between the modulator and the demodulator.

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

the electrically-isolating acoustic coupler comprises a decoupled stacked bulk acoustic resonator (DSBAR); and

the DSBAR comprises a first film bulk acoustic resonator (FBAR), a second FBAR, and an 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 2, in which the electrically-isolating acoustic coupler comprises no more than one decoupled stacked bulk acoustic resonator (DSBAR).

5. The acoustic galvanic isolator of claim 4, in which the acoustic decoupler is electrically insulating and is the sole provider of electrical isolation between the modulator and the demodulator.

6. The acoustic galvanic isolator of claim 2, additionally comprising an acoustically-resonant electrical insulator located between the FBARs.

7. The acoustic galvanic isolator of claim 6, 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 acoustic galvanic isolator of claim 6, in which the acoustically-resonant electrical insulator comprises a layer of electrically-insulating material matched in acoustic impedance with the FBARs.

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

the acoustic galvanic isolator additionally comprises an additional acoustic decoupler located between the FBARs; and

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

10. The acoustic galvanic isolator of claim 9, in which the layer of electrically-insulating material is a one quarter-wave layer.

11. The acoustic galvanic isolator of claim 9, in which at least one of the acoustic decouplers is electrically insulating.

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

the acoustically-resonant electrical insulator is a first acoustically-resonant electrical insulator and comprises a half-wave layer of electrically-insulating material;

the acoustic galvanic isolator additionally comprises a second acoustically-resonant electrical insulator between the FBARs, the second acoustically-resonant electrical insulator comprising a half-wave layer of electrically-insulating material; and

the acoustic decoupler is located between the first half-wave acoustically-resonant electrical insulator and the second half-wave acoustically-resonant electrical insulator.

13. The acoustic galvanic isolator of claim 12, in which the acoustic decoupler is electrically insulating.

14. The acoustic galvanic isolator of claim 1, in which the electrically-isolating acoustic coupler comprises a film acoustically-coupled transformer (FACT).

15. The acoustic galvanic isolator of claim 14, in which the FACT comprises:

a first decoupled stacked bulk acoustic resonator (DSBAR) and a second 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

a first electrical circuit interconnecting the first FBARs of the DSBARs and connecting the first FBARs to the modulator; and

a second electrical circuit interconnecting the second FBARs of the DSBARs and connecting the second FBARs to the demodulator.

16. The acoustic galvanic isolator of claim 15 in which:

the first electrical circuit connects the first FBARs in anti-parallel; and

the second electrical circuit connects the second FBARs in series.

17. The acoustic galvanic isolator of claim 16, in which:

each of the FBARs comprises a piezoelectric element; and

the piezoelectric element of the second FBAR of each DSBAR collectively provide electrical isolation between the modulator and the demodulator.

18. The acoustic galvanic isolator of claim 15, in which:

the first electrical circuit connects the first FBARs in series; and

the second electrical circuit connects the second FBARs in series.

19. The acoustic galvanic isolator of claim 18, in which:

each of the FBARs comprises a piezoelectric element; and

the piezoelectric elements of both FBARs of each DSBAR collectively provide electrical isolation between the modulator and the demodulator.

20. The acoustic galvanic isolator of claim 18, in which:

the modulator has a differential output connected to the first electrical circuit; and

the demodulator has a differential input connected to the second electrical circuit.

21. The acoustic galvanic isolator of claim 18, in which:

the FACT is a first FACT; and

the acoustic galvanic isolator additionally comprises a second FACT interposed between the modulator and the acoustic coupler, the second FACT comprising a first DSBAR and a second DSBAR, each DSBAR comprising a first FBAR and a second FBAR, the first FBARs connected in antiparallel and to the output of the modulator, the second FBARs connected in series and to the first electrical circuit.

22. The acoustic galvanic isolator of claim 21, in which an acoustic signal travels in the second FACT in an opposite direction to an acoustic signal in the first FACT.

23. The acoustic galvanic isolator of claim 15, in which:

each of the FBARs comprises a piezoelectric element; and

the piezoelectric element of the second FBAR of each DSBAR provides electrical isolation between the modulator and the demodulator.

24. The acoustic galvanic isolator of claim 1, in which the electrically-isolating acoustic coupler comprises series-connected decoupled stacked bulk acoustic resonators (DSBARs).

25. The acoustic galvanic isolator of claim 23, in which the acoustic coupler comprises:

a first decoupled stacked bulk acoustic resonator (DSBAR) and a second 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 electrical circuit connecting the DSBARs in series between the modulator and the demodulator.

26. The acoustic galvanic isolator of claim 25, in which the electrical circuit connects the DSBARs in series by connecting the second FBARs of the DSBARs in parallel.

27. The acoustic galvanic isolator of claim 26, in which the acoustic decoupler of at least one of the DSBARs is electrically insulating and provides electrical isolation between the modulator and the demodulator.

28. The acoustic galvanic isolator of claim 25, in which the electrical circuit connects the DSBARs in series by connecting the second FBARs of the DSBARs in anti-parallel.

29. The acoustic galvanic isolator of claim 28, in which:

each of the FBARs comprises a piezoelectric element; and

the piezoelectric element of the second FBAR of each DSBAR provides electrical isolation between the modulator and the demodulator.

30. The acoustic galvanic isolator of claim 28, in which the acoustic decoupler of at least one of the DSBARs is electrically insulating and provides additional electrical isolation between the modulator and the demodulator.

31. The acoustic galvanic isolator of claim 1, in which the electrically-isolating acoustic coupler comprises film bulk acoustic resonators (FBARs).

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

providing an electrically-isolating acoustic coupler;

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.

33. The method of claim 32, in which the acoustically coupling comprises:

generating an acoustic signal in response to the modulated electrical signal; and

passing the acoustic signal through an electrically-insulating acoustic decoupler.

34. The method of claim 33, in which the acoustically coupling additionally comprises passing the acoustic signal through an acoustically-resonant electrical insulator.

35. The method of claim 34, in which the acoustically-resonant electrical insulator is a quarter-wave acoustically-resonant electrical insulator.

36. The method of claim 34, in which the acoustically-resonant electrical insulator is a half-wave acoustically-resonant electrical insulator.

37. The method of claim 32, in which the acoustically coupling comprises:

generating antiphase acoustic signals in response to the modulated electrical signal;

passing the antiphase acoustic signals through respective acoustic decouplers;

converting the acoustic signals passed through the acoustic decouplers to respective recovered electrical signals; and

summing the recovered electrical signals.

38. The method of claim 32, in which the acoustically coupling comprises repetitively performing a process comprising:

generating an acoustic signal in response to a first electrical signal, the first electrical signal being the modulated electrical signal in the first performance of the process and being a second electrical signal in each subsequent performance;

passing the acoustic signal through an acoustic decoupler; and

converting the acoustic signal passed through the acoustic decoupler to provide the second electrical signal in all but the last performance and to provide the modulated electrical signal acoustically coupled through the electrically-isolating acoustic coupler in the last performance.