CIRCUIT, SYSTEM AND METHOD FOR FAR-FIELD RADIATIVE POWERING OF AN IMPLANTABLE MEDICAL DEVICE

• US 20130253612A1
• Filed: 05/24/2013
• Published: 09/26/2013
• Est. Priority Date: 07/14/2011
• Status: Active Grant

• Current Assignee: LivaNova USA, Inc. (LivaNova Plc)
• Original Assignee: Cyberonics, Inc
• Inventors: CHOW, Eric Y.
• Granted Patent: US 9,675,809 B2
• Time in Patent Office: Days
• US Class Current: 607/60
• CPC Class Codes: A61N 1/37229 Shape or location of the implanted or external antenna
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves

Abstract

An isolated circuit including a RF input configured to receive a far field radiative powering signal and a rectified voltage output configured to provide a rectified voltage based on the received far field radiative powering signal. The isolated circuit also includes a first power assembly comprising a first impedance coupled to the RF input where the first impedance is provided, at least in part, by activating a first switch in response to the rectified voltage satisfying a first voltage threshold. The isolated circuit also includes a second power assembly comprising a second impedance coupled to the RF input where the second impedance is provided, at least in part, by activating the first switch and a second switch in response to the rectified voltage satisfying the first voltage threshold and a second voltage threshold, respectively.

Claims

1. An isolated circuit comprising:

a RF input configured to receive a far field radiative powering signal;

a rectified voltage output configured to provide a rectified voltage based on the received far field radiative powering signal;

a first power assembly comprising a first impedance coupled to the RF input, the first impedance provided, at least in part, by activating a first switch in response to the rectified voltage satisfying a first voltage threshold; and

a second power assembly comprising a second impedance coupled to the RF input, the second impedance provided, at least in part, by activating the first switch and a second switch in response to the rectified voltage satisfying the first voltage threshold and a second voltage threshold, respectively.

2. The isolated circuit of claim 1, further comprising:

a first threshold detector coupled to the second switch, the first threshold detector configured to receive the rectified voltage and to activate the second switch when the rectified voltage increases to the second voltage threshold.

3. The isolated circuit of claim 2, wherein the first switch is a first transistor and the second switch is a second transistor.

4. The isolated circuit of claim 3, wherein the first threshold detector is a first voltage divider configured to divide the rectified voltage and to provide a first divided rectified voltage to the second transistor.

5. The isolated circuit of claim 4, wherein the first divided rectified voltage activates the second transistor when the rectified voltage is at, or above, the second voltage threshold.

6. The isolated circuit of claim 5, further comprising:

a third power assembly comprising a third impedance coupled to the RF input, the third impedance provided, at least in part, by activating the first switch, the second switch, and a third switch in response to the rectified voltage satisfying the first voltage threshold, the second voltage threshold, and a third threshold, respectively; and

a second threshold detector coupled to the third switch, the second threshold detector configured to receive the rectified voltage and to activate the third switch when the rectified voltage increases to the third voltage threshold.

7. The isolated circuit of claim 6, wherein the third switch is a third transistor, wherein the second threshold detector is a second voltage divider configured to divide the rectified voltage and to provide a second divided rectified voltage to the third transistor.

8. The isolated circuit of claim 7, wherein the second divided rectified voltage activates the third transistor when the rectified voltage is at, or above, the third voltage threshold.

9. The isolated circuit of claim 8, wherein the first voltage divider comprises at least a first diode-connected transistor and a second diode-connected transistor, the first diode-connected transistor coupled to the rectified voltage output, the first diode-connected transistor also coupled to the second transistor and the second diode-connected transistor;

and

wherein the second voltage divider comprises at least a third diode-connected transistor and a fourth diode-connected transistor, the third diode-connected transistor coupled to the rectified voltage output, the third diode-connected transistor also coupled to the third transistor and the fourth diode-connected transistor.

10. The isolated circuit of claim 9, wherein at least one dimension of the first diode-connected transistor is greater than that of the third diode-connected transistor.

11. The isolated circuit of claim 3, wherein rectified voltage is provided to the first transistor and activates the first transistor at the first voltage threshold.

12. The isolated circuit of claim 1, wherein the first impedance and the second impedance comprise a resistor, a capacitor, an inductor, a diode, a transistor, or a combination thereof.

13. An implantable medical device, comprising:

an antenna;

a matching network coupled to the antenna, the antenna and the matching network together configured to receive a far field radiative powering signal, the matching network configured to provide a matching impedance to the antenna;

a voltage rectifier coupled to the matching network, the voltage rectifier configured to rectify the received far field radiative powering signal and to output a rectified voltage based on the received far field radiative powering signal; and

an impedance feedback circuit configured to adjust the matching impedance of the matching network based on the rectified voltage.

14. The implantable medical device of claim 13, wherein the impedance feedback circuit includes a first switch coupled to the matching network and a second switch coupled to the matching network, the first switch configured to couple a first impedance to the matching network when the first switch is activated in response to the rectified voltage satisfying a first voltage threshold, the second switch configured to couple a second impedance to the matching network when the second switch is activated in response to the rectified voltage satisfying a second voltage threshold.

15. The implantable medical device of claim 14, wherein the impedance feedback circuit further comprises a first threshold detector coupled to the second switch, the first threshold detector configured to receive the rectified voltage and to activate the second switch when the rectified voltage increases to the second voltage threshold.

16. The implantable medical device of claim 15, wherein the first switch is a first transistor and the second switch is a second transistor.

17. The implantable medical device of claim 16, wherein the first threshold detector is a first voltage divider configured to divide the rectified voltage and to provide a first divided rectified voltage to the second transistor, wherein the first divided rectified voltage activates the second transistor when the rectified voltage is at, or above, the second voltage threshold.

18. An antenna assembly, comprising:

a receiving element configured to receive a far field powering signal;

a load coupled to the receiving element, the load having a load impedance that varies non-linearly with variations in the far field powering signal, the load comprising;

a matching network coupled to the receiving element;

a voltage rectifier coupled to the matching network, the voltage rectifier configured to output a rectified voltage based on the received far field radiative powering signal;

an impedance feedback circuit configured to receive the rectified voltage from the voltage rectifier, the impedance feedback circuit configured to activate a first switch when the rectified voltage reaches a first rectified voltage threshold and to activate a second switch when the rectified voltage reaches a second rectified voltage threshold, the first switch configured to couple a first impedance to the load to adjust the load impedance when the first switch is activated, the second switch is configured to couple a second impedance to the load to adjust the load impedance when the second switch is activated.

19. The antenna assembly of claim 18, wherein the first switch is a first transistor and the second switch is a second transistor, the impedance feedback circuit further comprising a first voltage divider configured to divide the rectified voltage and to provide a first divided rectified voltage to the second transistor, wherein the first divided rectified voltage activates the second transistor when the rectified voltage is at, or above, the second voltage threshold.

20. The antenna assembly of claim 19, wherein rectified voltage is provided to the first transistor and activates the first transistor at the first voltage threshold.