Power consumption reduction in medical devices employing multiple digital signal processors

• US 6,185,460 B1
• Filed: 07/22/1999
• Issued: 02/06/2001
• Est. Priority Date: 04/29/1998
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Thompson, David L.
• Primary Examiner(s): EVANISKO, GEORGE ROBERT
• Application Number:
  US09/359,102
• Time in Patent Office: 565 Days
• Field of Search: 607/4, 607/5, 607/9, 607/16
• US Class Current: 607/16
• CPC Class Codes: A61N 1/378 Electrical supply
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/324 by lowering clock frequency
• CPC Class Codes: G06F 1/3296 by lowering the supply or operating voltage
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

Power consumption in medical devices is reduced through the use and operation of multiple digital signal processing systems. Each processor of the multiple systems performs at least one particular function in a predetermined time period. The multiple digital signal processors of such systems can be operated at lower clock frequencies relative to those that would be required by one of such processors to complete the multiple functions within the predetermined time period. With reduced clock frequency, power consumption is reduced. Further, with reduced clock speed, supply voltages applied to such digital signal processors may also be reduced.

Claims

1. A medical device adapted to be implanted in a living body for delivering a therapy to a patient'"'"'s body or monitoring a physiologic condition of a patient comprising:

an electrical stimulation therapy delivery circuits; and

a physiological condition monitoring circuit;

a battery to provide battery energy; and

an operating system powered by the battery energy providing control and timing functions associated with the delivery of the therapy to the patient'"'"'s body or monitoring a physiologic condition of the patient further comprising;

a system clock circuit powered by the battery energy and having a first output clock signal at a first clock frequency and a second output clock signal at a second clock frequency;

means for timing a predetermined time period;

a first analog signal input;

a second analog signal input; and

a first digital signal processing system receiving the first analog input, the first digital signal processing system including first digital signal processor operating at the first clock frequency on the first analog input to convert the analog input into a first digital data signal and to perform at least a first detection function during the predetermined time period; and

a second digital signal processing system receiving the second analog input, the second digital signal processing system including a second digital signal processor operating at the second clock frequency on the second analog input to convert the analog input into a second digital data signal and to perform at least a second detection function during the predetermined time period,

wherein the first and second clock frequencies reduce the power consumed by the first and second digital signal processors in performance of the first and second detection functions to a level that is less than the power that would be consumed if only one of the first and second digital signal processors were to perform both of the first and second detection functions within the predetermined time period.

2. The medical device of claim 1, wherein the first and second clock frequencies are about the same.

3. The medical device of claim 1, wherein the first and second clock frequencies are different.

4. The medical device of claim 1, wherein the predetermined time period is a time period based on physiological events.

5. The medical device of claim 1, wherein the electrical stimulation therapy delivery circuit generates cardiac pacing stimulation pulses and one of the first and second analog signal inputs accepts a cardiac signal.

6. The medical device of claim 1, wherein the device further includes a supply voltage source connected with said battery for applying a first supply voltage to the first digital signal processor correlated with the first clock frequency and for applying a second supply voltage to the second digital signal processor correlated with the second clock frequency.

7. The medical device of claim 6, wherein the first and second clock signals are about equal, and further wherein the first supply voltage and the second supply voltage are about equal.

8. The medical device of claim 1, wherein the system clock provides a further clock signal having a further clock frequency, and the operating system further comprises:

further analog input means for providing at least a further analog input representing at least one of a device state, a device function or a monitored physiologic condition of the patient;

a further digital signal processing system receiving the further analog input, the further digital signal processing system including a further digital signal processor operating at the further clock frequency on the further analog input to convert the analog input into a further digital data signal and to perform at least a further detection function during the predetermined time period; and

wherein the first, second, and further clock frequencies are such that the power consumed by the first, second, and further digital signal processors in performance of the first, second, and further functions is less than the power that would be consumed if only one of the first, second, and further digital signal processors were to perform the first, second, and further functions within the predetermined time period.

9. The medical device of claim 1, wherein at least one of the first and second detection functions is selected from the group consisting of capture detection, R-wave detection, P-wave detection, T-wave detection, electromagnetic interference detection, oxygen saturation determination, pressure determination, sensor cardiac contractility determination, cardiac flow determination, telemetry reception and telemetry transmission.

10. The medical device of claim 1, wherein the medical device is an hermetically sealed implantable medical device.

11. The medical device of claim 10, wherein the implantable medical device is selected from the group consisting of an implantable stimulator, an implantable nerve stimulator, an implantable pacemaker, an IPG, an implantable cardioverter, an implantable PCD, an implantable defibrillator, an ICD and an implantable drug pump.

12. The medical device of claim 1, wherein at least one of the first and second digital processing systems comprise circuits selected from the group consisting of CMOS circuits, CML circuits, SOS circuits, SOI circuits, BICMOS circuits, PMOS circuits and NMOS circuits.

13. A method of reducing power consumption in a medical device adapted to be implanted in a living body and powered by a battery providing battery energy for delivering a therapy to a patient'"'"'s body and/or monitoring a physiologic condition of a patient, comprising the steps of:

generating a first clock signal having a first clock frequency and a second clock signal having a second clock frequency;

timing a predetermined time period associated with the delivery of a therapy to the patient'"'"'s body and/or monitoring a physiologic condition of the patient;

sensing a first analog input representing at least one of a device state, a device function or a monitored physiologic condition of the patient during the predetermined time period;

sampling and digitizing the first analog signal to provide a first digitized input signal, using a first digital signal processor;

applying the first clock signal to the first digital signal processor;

operating the first digital signal processor at the first clock frequency to perform at least a first detection function during at least a portion of the predetermined time period;

sensing a second analog input representing at least one of a device state, a device function or a monitored physiologic condition of the patient during the predetermined time period;

sampling and digitizing the second analog signal to provide a second digitized input signal using a second digital signal processor;

applying the second clock signal to the second digital signal processor;

operating the second digital signal processor at the second clock frequency to perform at least a second detection function during at least a portion of the predetermined time period,

wherein the first and second clock frequencies are such that the power consumed by the first and second digital signal processors in performance of the first and second functions is less than the power that would be consumed if only one of the first and second digital signal processors were to perform both of the first and second functions within the predetermined time period.

14. The method of claim 13, further comprising:

providing a further clock signal having a further clock frequency and a second clock signal having a second clock frequency;

sensing a further analog input representing at least one of a device state, a device function or a monitored physiologic condition of the patient during the predetermined time period;

sampling and digitizing the further analog signal to provide a further digitized input signal, using a further digital signal processor;

applying the further clock signal to a further digital signal processor; and

operating the further digital signal processor at the further clock frequency to perform at least a further detection function during at least a portion of the predetermined time period,

wherein the first, second, and further clock frequencies are such that the power consumed by the first, second, and further digital signal processors in performance of the first, second, and further functions is less than the power that would be consumed if only one of the first, second, and further digital signal processors were to perform the first, second and further functions within the predetermined time period.

15. The method of claim 13, wherein the first and second clock frequencies are about equal.

16. The method of claim 13, wherein the predetermined time period is a time period based on physiological events.

17. The method of claim 13, wherein the medical device is adapted to be implanted in a living body for delivering a therapy to a patient'"'"'s heart or monitoring a physiologic condition of the patient including cardiac signals, wherein

at least one of the first and second analog inputs is a cardiac signal.

18. The method of claim 13, wherein the medical device is adapted to be implanted in a living body for delivering a therapy to a patient'"'"'s heart or monitoring a physiologic condition of the patient, and wherein the method further includes:

applying a first supply voltage to the first digital signal processor correlated with the first clock frequency; and

applying a second supply voltage to the second digital signal processor correlated with the second clock frequency.

19. The method of claim 18, wherein the first and second clock signals are about equal, and further wherein the first supply voltage and the second supply voltage are about equal.

20. The method of claim 13, wherein the medical device is adapted to be implanted in a living body for delivering a therapy to a patient'"'"'s heart or monitoring a physiologic condition of the patient and, wherein at least one of the first and second detection functions is selected from the group consisting of capture detection, R-wave detection, P-wave detection, T-wave detection, electromagnetic interference detection, oxygen saturation determination, pressure determination, sensor cardiac contractility determination, cardiac flow determination, telemetry reception and telemetry transmission.

21. The method of claim 13, wherein the medical device is an hermetically sealed implantable medical device.

22. The method of claim 21, wherein the implantable medical device is selected from the group consisting of an implantable stimulator, an implantable nerve stimulator, an implantable pacemaker, an IPG, an implantable cardioverter, an implantable PCD, an implantable defibrillator, an ICD and an implantable drug pump.

23. The method of claim 13, wherein at least one of the first and second digital processors comprise circuits selected from the group consisting of CMOS circuits, CML circuits, SOS circuits, SOI circuits, BICMOS circuits, PMOS circuits and NMOS circuits.