Acoustically communicating data signals across an electrical isolation barrier

• US 20070086274A1
• 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 General IP PTE Limited (Broadcom, Inc.)
• Inventors: Nishimura, Ken, Larson, John, Gilbert, Stephen
• Granted Patent: US 7,525,398 B2
• Time in Patent Office: Days
• US Class Current: 367/140
• CPC Class Codes: H04B 11/00 Transmission systems employing sonic, ultrasonic or infrasonic waves
• CPC Class Codes: H04L 27/10 Frequency-modulated carrier systems, i.e. using frequency-shift keying H04L27/32 takes precedence
• CPC Class Codes: H04L 27/18 Phase-modulated carrier systems, i.e. using phase-shift keying H04L27/32 takes precedence

Abstract

In one aspect, a data communication system includes a modulator, an integrated acoustic data coupler, and a demodulator. The modulator modulates a carrier signal having a frequency in an operating frequency range in response to an input data signal and provides the modulated carrier signal at a modulator output. The integrated acoustic data coupler includes an acoustically resonant structure that has one or more acoustic resonant frequencies in the operating frequency range. The acoustically resonant structure includes a first thin film electro-acoustic transducer electrically coupled to the modulator output, a second thin film electro-acoustic transducer, and a substrate. The substrate supports, acoustically couples, and provides an electrical isolation barrier between the first and second thin film electro-acoustic transducers. The demodulator has a demodulator input coupled to the second thin film electro-acoustic transducer and is operable to generate an output data signal from an input signal received at the demodulator input.

Claims

1. A system for communicating a data signal across an electrical isolation barrier, comprising:

a modulator operable to modulate a carrier signal having a frequency in an operating frequency range in response to an input data signal and to provide the modulated carrier signal at a modulator output;

an integrated acoustic data coupler comprising an acoustically resonant structure that has one or more acoustic resonant frequencies in the operating frequency range, the acoustically resonant structure comprising

a first thin film electro-acoustic transducer electrically coupled to the modulator output,

a second thin film electro-acoustic transducer, and

a substrate supporting, acoustically coupling, and providing an electrical isolation barrier between the first and second thin film electro-acoustic transducers; and

a demodulator having a demodulator input coupled to the second thin film electro-acoustic transducer and operable to generate an output data signal from an input signal received at the demodulator input.

2. The system of claim 1, wherein the operating frequency range has a lower bound of 10 MHz.

3. The system of claim 1, wherein the acoustically resonant structure has a fundamental resonant frequency in a range of 99% to 101% of the frequency of the carrier signal.

4. The system of claim 1, wherein the substrate comprises electrically insulating material between the first and second thin film electro-acoustic transducers.

5. The system of claim 1, wherein the integrated acoustic data coupler draws a current of at most 10 mA when 1,000 V is applied across the integrated acoustic data coupler.

6. The system of claim 1, further comprising a first electrical ground path between the first thin film electro-acoustic transducer and the modulator and a second electrical ground path between the second thin film electro-acoustic transducer and the demodulator, wherein the first and second electrical ground paths are disconnected electrically from each other.

7. The system of claim 6, further comprising a third electrical ground path between the first and second electrical ground paths, wherein the third electrical ground path is electrically isolated from both the first and second electrical ground paths.

8. The system of claim 1, wherein each of the first and second thin film electro-acoustic transducers comprises a layer of piezoelectric material between a first electrode and a second electrode.

9. The system of claim 1, wherein the substrate has a thickness normal to surfaces of the substrate respectively supporting the first and second thin film electro-acoustic transducers in a range from 0.1 μ

m to 1000 μ

m.

10. The system of claim 1, wherein each of the first and second thin film electro-acoustic transducers has at least one respective lateral dimension in a plane normal to a surface of the substrate supporting the respective thin film electro-acoustic transducer that is in a range from 50 μ

m to 5000 μ

m.

11. The system of claim 1, further comprising a first amplifier coupled between the modulator and the integrated acoustic data coupler and operable to amplify the modulated carrier signal, and a second amplifier coupled between the demodulator and the integrated acoustic data output and operable to amplify an output electrical signal produced by the integrated acoustic data coupler.

12. The system of claim 1, wherein the modulator comprises a frequency modulator that modulates the frequency of the carrier signal in response to the input data signal.

13. The system of claim 1, wherein the modulator comprises an amplitude modulator that modulates the amplitude of the carrier signal in response to the input data signal.

14. The system of claim 1, wherein the modulator comprises a phase modulator that modulates the phase of the carrier signal in response to the input data signal.

15. The system of claim 1, wherein the demodulator comprises a frequency modulation detector that generates the output data signal with logic levels responsive to frequency variations in the input signal received at the demodulator input.

16. The system of claim 1, wherein the demodulator comprises an amplitude modulation detector that generates the output data signal with logic levels responsive to amplitude variations in the input signal received at the demodulator input.

17. The system of claim 1, wherein the demodulator comprises a phase modulation detector that generates the output data signal with logic levels responsive to phase variations in the input signal received at the demodulator input.

18. The system of claim 1, further comprising:

p1 an oscillator operable to generate an input AC electrical power signal at a frequency within the operating frequency range;

a third thin film electro-acoustic transducer and a fourth thin film electro-acoustic transducer on opposite sides of the substrate, wherein the third thin film electro-acoustic transducer converts the input AC electrical power signal into acoustic energy that is coupled across the substrate and is converted by the fourth thin film electro-acoustic transducer into an output AC electrical power signal; and

a rectifying circuit coupled to the fourth thin film electro-acoustic transducer and operable to convert the output AC electrical power signal into DC electrical power.

19. The system of claim 1, further comprising a second substrate, a third substrate, and a fourth substrate, wherein the modulator is mounted on the second substrate, the integrated acoustic data coupler is mounted on the third substrate, and the demodulator is mounted on the fourth substrate.

20. The system of claim 1, wherein the modulator and the first thin film electro-acoustic transducer are on a first side of the substrate, and the demodulator and the second thin film electro-acoustic transducer are on a second side of the substrate opposite the first side.

21. A method of communicating a data signal across an electrical isolation barrier, comprising:

modulating a carrier signal having frequency of at least 10 MHz in response to an input data signal;

converting an input electrical signal corresponding to the modulated carrier signal into acoustic energy;

coupling the acoustic energy across an electrical isolation barrier;

converting the acoustic energy coupled across the electrical isolation barrier into an output electrical signal; and

generating an output data signal from the output electrical signal.