Inductive data and power link suitable for integration

• US 20050063488A1
• Filed: 09/22/2003
• Published: 03/24/2005
• Est. Priority Date: 09/22/2003
• Status: Active Grant

• Current Assignee: LunaNeuro LLC
• Original Assignee: Glenn Anthony Demichele, Philip Richard Troyk
• Inventors: Troyk, Philip Richard, DeMichele, Glenn Anthony
• Granted Patent: US 7,271,677 B2
• Time in Patent Office: Days
• US Class Current: 375/316
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: H04B 5/00 Near-field transmission systems, e.g. inductive or capacitive transmission systems
• CPC Class Codes: H04B 5/0012 using capacitive coupling
• CPC Class Codes: H04B 5/0031 for data transfer
• CPC Class Codes: H04B 5/0037 for power transfer
• CPC Class Codes: H04B 5/22 Capacitive coupling
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer
• CPC Class Codes: H04L 27/10 Frequency-modulated carrier systems, i.e. using frequency-shift keying H04L27/32 takes precedence

Abstract

A system providing an inductive power and data link between an external transmitter and miniature internal receiver is presented. The system is suited to applications where the receiver must be of a small size and the system must consume very little power, such as an implanted biomedical device. The system is also compatible with systems where bi-directional communications are required. The novel transmitter and receiver form an improved forward data telemetry system. The transmitter consists of a Class-E converter with its optimum operating frequency being synchronously, instantaneously and efficiently altered in accordance with the data to be transmitted, thereby producing an FSK modulated magnetic field of substantially constant amplitude. The constant amplitude output allows for the continuous, data-independent transfer of power to the miniature receiver and its associated electronics. The present invention also represents an improvement over the high efficiency Class-E converters previously patented by the inventors. The receiver consists of a coil and an integrated rectifying system to recover operating power from the incident magnetic field, as well as an FSK demodulator whose operation is based on the multiphase comparison of charging times of integrated capacitors. The described FSK demodulator approach removes deleterious effects resulting from low-frequency changes in the transmitter frequency, and eliminates time distortion artifacts generated by circuit imbalances and asymmetries in the power recovery process. The combination of the transmitter and receiver improvements yields a reliable data transfer system unaffected by circuit imbalances and incidental variations in the amplitude and frequency of the magnetic field.

Claims

1. In a high-Q resonant circuit transmitter, having a transmitter coil, carrying a transmitter coil current, the improvement comprising:

a means for frequency-shift-keyed modulation of a transmitter coil current whereby the frequency of said transmitter coil current is substantially instantaneously changed in a manner that results in little to no energy loss from the high-Q resonant circuit transmitter.

2. In a high-Q resonant transmitter as in claim 1, further comprising storage means for storage of energy of said high-Q resonant circuit transmitter during said frequency-shift-keyed modulation of said transmitter coil current.

3. In a high-Q resonant circuit transmitter as in claim 1, further comprising switching means having conducting and non-conducting states, wherein said switching means switches between a conducting and non-conducting state to produce said frequency-shift-keyed modulation of said transmitter coil current.

4. In a high-Q resonant circuit transmitter as in claim 2, wherein said storage means comprises at least one capacitor.

5. A method for frequency-shift-keyed modulation of a transmitter coil current of a high-Q resonant circuit transmitter, said transmitter having one or more distinct states of operation characterized by one or more distinct frequencies, comprising:

storing energy within said high-Q resonant circuit transmitter; and

switching of said stored energy so as to instantaneously change the frequency of said transmitter coil current.

6. A method for frequency-shift-keyed modulation of a transmitter coil current of a high-Q resonant circuit transmitter as in claim 5, wherein the stored energy of said resonant circuit is stored in at least one capacitor.

7. A method for frequency-shift-keyed modulation of a transmitter coil current of a high-Q resonant circuit transmitter as in claim 5, wherein the transition time between said distinct states is approximately zero.

8. A method for frequency-shift-keyed modulation of a transmitter coil current of a high-Q resonant circuit transmitter as in claim 5, wherein the operation of said high-Q resonant circuit transmitter during said distinct states is independent between said states.

9. A method for frequency-shift-keyed modulation of a transmitter coil current of a high-Q resonant circuit transmitter as in claim 5, wherein said distinct states are characterized by a high and low frequency.

10. A method for frequency-shift-keyed modulation of a transmitter coil current of a high-Q resonant circuit transmitter as in claim 5, wherein switching between said distinct states is accomplished with little to no energy loss.

11. In a frequency-shift-keyed demodulation receiver circuit, for decoding a frequency-shift-keyed signal having multiple half cycles, the improvement comprising:

means for decoding said frequency-shift-keyed signal by comparing the time duration of one or more of said half-cycles of said frequency-shift-keyed signal to an average value of the time duration of multiple half-cycles of said frequency-shift-keyed signal.

12. In a frequency-shift-keyed demodulation receiver circuit as in claim 11, wherein said decoding means comprises a multiphase demodulator.

13. In a frequency-shift-keyed demodulation receiver circuit as in claim 12, wherein said multiphase demodulator comprises one or more averaging capacitors and one or more adaptive threshold detectors.

14. A method for frequency-shift-keyed demodulation of an alternating current waveform having multiple half-cycles, comprising:

comparing the time duration of one or more half-cycles of said alternating current waveform to an average value of the time duration of multiple half-cycles of said alternating current waveform.

15. A method for frequency-shift-keyed demodulation of an alternating current waveform having multiple half-cycles as in claim 14, wherein the comparison of said time duration is accomplished using a multiphase demodulator circuit.

16. A method for frequency-shift-keyed demodulation of an alternating current waveform having multiple half-cycles as in claim 14, wherein comparison of the average of multiple time durations is accomplished using one or more averaging capacitors.

17. A power and communication system for an implantable device comprising:

a high-Q resonant circuit transmitter;

a means for producing frequency-shift-keyed modulation of a transmitter coil current whereby the frequency of said transmitter coil current is substantially instantaneously changed in a manner that results in little to no energy loss from the transmitter circuit; and

a frequency-shift-keyed demodulation circuit whereby said demodulation circuit comprises means for decoding a frequency-shift-keyed signal by comparing the time duration of one or more half-cycles of said frequency-shift-keyed signal to an average value of the time duration of multiple half-cycles of said frequency-shift-keyed signal.

18. A power and communication system as in claim 17, further comprising storage means for storage of energy of said resonant circuit during said frequency-shift-keyed modulation of said transmitter coil current.

19. A power and communication system as in claim 17, further comprising switching means having conducting and non-conducting states, said switching means to switch between a conducting and non-conducting state to produce said frequency-shift-keyed modulation of said transmitter coil current.

20. A power and communication system as in claim 18, wherein said storage means comprises at least one capacitor.

21. A power and communication system as in claim 17, wherein said frequency-shift-keyed demodulation circuit comprises a multiphase demodulator.

22. A power and communication system as in claim 21, wherein said multiphase demodulator comprises one or more averaging capacitors and one or more adaptive threshold detectors.