Power consumption reduction in medical devices employing just-in-time voltage control

• US 6,185,454 B1
• Filed: 04/09/1999
• 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): Getzow, Scott M.
• Application Number:
  US09/289,776
• Time in Patent Office: 669 Days
• Field of Search: 607/2, 607/9, 607/4, 607/10, 257/237, 257/254, 257/257, 257/258, 257/263, 257/265, 257/292, 257/500
• US Class Current: 607/2
• CPC Class Codes: A61N 1/025 Digital circuitry features of electrotherapy devices, e.g. memory, clocks, processors
• CPC Class Codes: A61N 1/36 for stimulation
• CPC Class Codes: A61N 1/3706 Pacemaker parameters stimulation threshold A61N1/371
• CPC Class Codes: A61N 1/3708 for power depletion
• CPC Class Codes: A61N 1/378 Electrical supply

Abstract

Power consumption in medical and battery powered devices is reduced through the use and operation of a data monitor which measures, senses or detects signals, inputs or outputs in a medical device before they are input to a principal or main digital signal processor, controller or microprocessor. In response to detecting or measuring such a signal which meets certain amplitude, frequency and/or phase characteristics, the data monitor directs or controls voltage supply circuits to increase or decrease the voltages provided to certain circuits within the medical device. The voltages so employed are tailored to reduce the amount of power consumed by the medical device while preserving computational performance.

Claims

1. A medical device, comprising:

at least one circuit operable to perform at least one function and having at least one of a first input and a first output connected thereto for receiving or outputting, respectively, a first input signal or a first output signal;

a power source for applying a first fixed supply voltage to at least first portions of the at least one circuit;

a voltage generation circuit having the first fixed supply voltage supplied thereto, the voltage generation circuit generating at least a second fixed supply voltage for application to at least second portions of the at least one circuit, the second fixed supply voltage being different from the first fixed supply voltage;

a processing device having a second input for receiving at least one of the first input signal and the first output signal, the first input signal or first output signal being input to the second output before or after having been subjected to any one of preliminary signal conditioning, filtering, amplification and logic processing, and

a monitor circuit connected between the second input and the first input or first output, the monitor circuit being operable to at least one of measure, sense and detect at least one predetermined characteristic of the first input signal or the first output signal, the monitor circuit being connected to the voltage generation circuit and being operable, in response to measuring, sensing or detecting the at least one predetermined characteristic, to cause the voltage generation circuit to at least one of provide the second fixed supply voltage to the at least second portions of the at least one circuit and provide the first fixed supply voltage to the at least first portions of the at least one circuit.

2. The device of claim 1, wherein the second fixed supply voltage is greater than the first fixed supply voltage.

3. The device of claim 1, wherein the first fixed supply voltage is greater than the second fixed supply voltage.

4. The device of claim 1, wherein the at least one circuit further comprises one or more analog circuits operable to perform at least one function.

5. The device of claim 4, wherein the one or more analog circuits include at least one of an atrial sense amplifier, a ventricular sense amplifier, a T-wave amplifier, one or more bandpass filters, one or more detection circuits, one or more sensor amplification circuits, one or more physiological signal amplification circuits, one or more output circuits, a battery monitor circuit, and a power on reset circuit.

6. The device of claim 4, wherein the one or more analog circuits include at least one amplifier circuit for amplifying the one or more analog signals.

7. The method of claim 1, wherein the at least one circuit further comprises one or more digital circuits operable to perform at least one function.

8. The device of claim 7, wherein the device further includes means for adjusting the back gate bias of at least one of the one or more digital circuits.

9. The device of claim 7, wherein the one or more digital circuits include at least one of a processor, a controller and a memory.

10. The device of claim 7, wherein the one or more digital circuits include at least one digital signal processor having the first supply voltage applied thereto receiving data representative of one or more analog signals.

11. The device of claim 1, wherein the voltage generation circuit is a charge pump circuit for generating the second fixed supply voltage based on the first fixed supply voltage.

12. The device of claim 1, wherein the first supply voltage ranges between about 0.8 volts and about 1.5 volts.

13. The device of claim 1, wherein the second supply voltage ranges between about +/−

2.0 volts and about +/−

3.0 volts.

14. The device of claim 1, wherein the at least one circuit further comprises one or more analog circuits, one or more digital circuits, and a level shifter to translate signals between the one or more analog circuits and the one or more digital circuits.

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

16. The device of claim 15, 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 implantable ICD and an implantable drug pump.

17. The device of claim 1, wherein the at least one circuit comprises circuitry of a type selected from the group consisting of a CMOS circuit, a CML circuit, an SOS circuit, an SOI circuit, a BICMOS circuit, a PMOS circuit and an NMOS circuits.

18. The device of claim 1, wherein the processing device is selected from the group consisting of a microprocessor, a microcomputer, a controller, a microcontroller, a digital signal processor, a CPU and an Application Specific Integrated Circuit (ASIC).

19. The device of claim 1, wherein the monitor circuit employs an adaptive control algorithm to determine whether or not a measured, sensed or detected signal meets the at least one predetermined characteristic.

20. The device of claim 19, wherein the at least one predetermined characteristic is defined in respect of at least one of the sign, polarity, slope, rate of change, amplitude, frequency and phase of the measured, sensed or detected signal.

21. The device of claim 1, wherein the first input or first output is selected from the group consisting of an output of a comparator, an output of a clock source, an output of a clock, an output of a supply voltage source, an output of an activity sensor, an output of a telemetry circuit, a sensing input from a pacing lead, and a sensing input from a defibrillating lead.

22. The device of claim 1, wherein the first input or first output is selected from the group consisting of sensed normal intrinsic sensed events, premature atrial contractions (PAC'"'"'s), premature ventricular contractions (PVC'"'"'s), atrial and/or ventricular tachycardia, atrial and/or ventricular flutter, atrial and/or ventricular fibrillation, noise, electromagnetic interference, muscle signals, far-field R-waves (FFRW), and antegrade or retrograde p-waves.

23. The device of claim 1, wherein the first input or first output is selected from the group consisting of sensed complete memory data dumps, sensed selected memory location uplinks, detected re-transmissions in a noisy environment, sensed telemetry distance, transmission power, receiver sensitivity, bit error rate (BER), and the amount of data telemetered or received.

24. The device of claim 1, wherein the first input or first output is selected from the group consisting of sampling rates, an activity rate response signal, a cardiac acceleration signal, and an oxygen saturation signal.

25. The device of claim 1, wherein the first input or first output is a sensed intra-circuit block activity per unit time.

26. The device of claim 1, wherein the first input or first output is selected from the group consisting of a sensed number of operand codes processed per unit time and a sensed type of operand codes processed per unit time.

27. The device of claim 1, wherein the first input or first output is selected from the group consisting of a sensed telemetry data format, a sensed telemetry data movement, a sensed Direct Memory Access (DMA) of an intra-cardiac electrogram, a sensed analog-to-digital converter sample rate, and a sensed analog-to-digital converter conversion rate.

28. The device of claim 1, wherein the first input or first output is selected from the group consisting of sensed activity along a bus, sensed activity within a controller, sensed activity within a microcontroller, sensed activity within a microprocessor, and sensed activity within a digital signal processor.

29. The device of claim 1, wherein the first input or first output is selected from the group consisting of a timed wakeup, an alarmed wakeup, a sensed interrupt for rate response calculation, a sensed completion of a diagnostic enable window, and a sensed acquisition of diagnostic data.

30. The device of claim 1, wherein the monitor circuit comprises a device selected from the group consisting of a microprocessor, a microcomputer, a controller, a microcontroller, a digital signal processor, a CPU, and an Application Specific Integrated Circuit (ASIC).

31. The device of claim 1, wherein the monitor circuit is operable to execute an adaptive control algorithm.

32. The device of claim 31, wherein the adaptive control algorithm permits at least some operating parameters of the medical device to be adjusted on the fly on the basis of the measured, sensed or detected first input or first output.

33. The device of claim 1, wherein the monitor circuit further measures, senses or detects data moving along at least one data bus.

34. The device of claim 1, wherein the monitor circuit is programmable.

35. The device of claim 1, wherein the monitor circuit is programmable with an adaptive control algorithm.

36. The device of claim 1, wherein the monitor circuit comprises a programmable digital signal processor capable of at least one of having and executing an adaptive control algorithm programmed therein.

37. The device of claim 36, wherein the digital signal processor is capable of carrying out adaptive filtering on the measured, sensed or detected first input or first output.

38. The device of claim 37, wherein the digital signal processor is programmable to be capable of discriminating between or detecting at least one of supraventricular tachycardia (SVT), atrial fibrillation (AF), atrial flutter (AFL), ventricular tachycardia (VT), ventricular fibrillation (VF), ventricular flutter (VFL), premature atrial contractions (PAC'"'"'s), premature ventricular contractions (PVC'"'"'s), signal-to-noise ratio of intrinsic cardiac signals, electromagnetic interference (EMI) and myopotentials.

39. The device of claim 1, further comprising a clock source for providing clock signals at a plurality of clock frequencies, the clock source being operatively connected to control the at least one circuit at a clock frequency such that substantially the entire predetermined time period is used to perform the at least one function, the function being completed just prior to the subsequent time period.

40. The device of claim 39, wherein the at least one circuit further comprises at least a first logic circuit for performing a first function and a second logic circuit for performing a second function, the first logic circuit being operable to perform the first function during a first predetermined time period and the second logic circuit being operable to perform the second function during a second predetermined time period, each of the first and second logic circuits being operated at a different clock frequency such that substantially the entire respective first and second predetermined time periods are used by the respective first and second logic circuits to perform the respective first and second functions.

41. The device of claim 40, wherein the first predetermined time period and the second predetermined time period are time periods based on physiological events.

42. The device of claim 41, wherein at least one of the first and second time periods is a time period associated with a cardiac event and is selected from the group consisting of a blanking interval, an upper rate interval, an escape interval, a refractory interval, and a pulse generator/programmer handshake.

43. The device of claim 39, wherein the processing device is operable to perform a plurality of functions, each of the plurality of functions being performed during an associated predetermined time period prior to a subsequent time period in which another of the plurality of functions is performed, the processing device being operable to perform each of two or more functions of the plurality of functions at a different clock frequency such that substantially the entire associated predetermined time period for each function is used to perform the functions prior to the subsequent time period in which another of the plurality of functions is performed.

44. The device of claim 43, wherein the associated predetermined time periods are time periods based on physiological events.

45. The device of claim 43, wherein at least one of the associated time periods is a time period associated with a cardiac event and is selected from the group consisting of a blanking interval, an upper rate interval, an escape interval, a refractory interval, and a pulse generator/programmer handshake.

46. The device of claim 39, wherein the first and second voltages are applied to the first and second portions of the at least one circuit as a function of the clock frequency applied to the at least one circuit.

47. The device of claim 46, wherein the at least one circuit comprises at least a first logic circuit for performing a first function and a second logic circuit for performing a second function, wherein each of the first and second logic circuits is operated at a different clock frequency, and further wherein the first and second logic circuits have the first and second supply voltages applied thereto, respectively, based on the different clock frequencies used to control the first and second logic circuits.

48. The device of claim 39, wherein the processing device is operable to perform a plurality of functions, each of at least two of the plurality of functions is performed at a different clock frequency, and the supply voltage applied to the processing device by the one or more voltage sources is adjusted such that the first supply voltage is provided to the processing device during performance of one of the at least two functions and a second supply voltage is provided to the processing device during performance of the other function, wherein the first and second supply voltages are applied to the processing device based on the different clock frequencies used to control the processing device.

49. The device of claim 1, wherein the device further comprises:

a multiplexer for receiving a plurality of analog signals; and

an analog to digital converter for converting one or more of the analog signals to digital signals and applying such digital signals to the processing device.

50. A method of conserving power in a medical device, comprising:

providing at least one circuit operable to perform at least one function and having at least one of a first input and a first output connected thereto for receiving or outputting, respectively, a first input signal or a first output signal;

providing a power source for applying a first fixed supply voltage to at least first portions of the at least one circuit;

providing a voltage generation circuit having the first fixed supply voltage supplied thereto, the voltage generation circuit generating at least a second fixed supply voltage for application to at least second portions of the at least one circuit, the second fixed supply voltage being different from the first fixed supply voltage;

providing a processing device having a second input for receiving at least one of the first input signal and the first output signal, the first input signal or first output signal being input to the second output before or after having been subjected to any one of preliminary signal conditioning, filtering, amplification and logic processing, and

providing a monitor circuit connected between the second input and the first input or first output, the monitor circuit being operable to at least one of measure, sense and detect at least one predetermined characteristic of the first input signal or the first output signal, the monitor circuit being connected to the voltage generation circuit and being operable, in response to measuring, sensing or detecting the at least one predetermined characteristic, to cause the voltage generation circuit to at least one of provide the second fixed supply voltage to the at least second portions of the at least one circuit and provide the first fixed supply voltage to the at least first portions of the at least one circuit.

51. The method of claim 50, wherein providing the at least one circuit further comprises providing one or more analog circuits operable to perform at least one function.

52. The method of claim 51, wherein providing the one or more analog circuits further comprises providing at least one of an atrial sense amplifier, a ventricular sense amplifier, a T-wave amplifier, one or more bandpass filters, is one or more detection circuits, one or more sensor amplification circuits, one or more physiological signal amplification circuits, one or more output circuits, a battery monitor circuit, and a power on reset circuit.

53. The method of claim 51, wherein providing the one or more analog circuits further comprises providing at least one amplifier circuit for amplifying the one or more analog signals.

54. The method of claim 50, wherein providing the at least one circuit further comprises providing one or more digital circuits operable to perform at least one function.

55. The method of claim 54, wherein providing one or more digital circuits further comprises providing means for adjusting the back gate bias of at least one of the one or more digital circuits.

56. The method of claim 54, wherein providing one or more digital circuits further comprises providing at least one of a processor, a controller and a memory.

57. The method of claim 54, wherein providing one or more digital circuits further comprises providing at least one digital signal processor having the first supply voltage applied thereto for receiving data representative of one or more analog signals.

58. The method of claim 50, wherein providing the voltage generation circuit further comprises providing a charge pump circuit for generating the second fixed supply voltage based on the first fixed supply voltage.

59. The method of claim 50, wherein providing the first supply voltage further comprises providing a voltage ranging between about 0.8 volts and about 1.5 volts.

60. The method of claim 50, wherein providing the second supply voltage further comprises providing a voltage ranging between about +/−

2.0 volts and about +/−

3.0 volts.

61. The method of claim 50, wherein providing the at least one circuit further comprises providing one or more analog circuits, one or more digital circuits, and a level shifter to translate signals between the one or more analog circuits and the one or more digital circuits.

62. The method of claim 50, further comprising hermetically sealing the medical device.

63. The method of claim 50, further comprising making the medical device an implantable medical device 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 implantable ICD and an implantable drug pump.

64. The method of claim 50, wherein providing the at least one circuit comprises providing circuitry of a type selected from the group consisting of a CMOS circuit, a CML circuit, an SOS circuit, an SOI circuit, a BICMOS circuit, a PMOS circuit and an NMOS circuit.

65. The method of claim 50, wherein providing the monitor circuit further comprises providing an adaptive control algorithm for operation therein or therewith to determine whether or not a measured, sensed or detected signal meets the predetermined characteristics.

66. The method of claim 50, wherein the at least one predetermined characteristic is defined in respect of at least one of the sign, polarity, slope, rate of change, amplitude, frequency and phase of the measured, sensed or detected signal.

67. The method of claim 50, wherein providing the first input or first output further comprises providing at least one of an output of a comparator, an output of a clock source, an output of a clock, an output of a supply voltage source, an output of an activity sensor, an output of a telemetry circuit, a sensing input from a pacing lead, and a sensing input from a defibrillating lead.

68. The method of claim 50, wherein providing the first input or first output further comprises providing at least one of sensed normal intrinsic sensed events, premature atrial contractions (PAC'"'"'s), premature ventricular contractions (PVC'"'"'s), atrial and/or ventricular tachycardia, atrial and/or ventricular flutter, atrial and/or ventricular fibrillation, noise, electromagnetic interference, muscle signals, far-field R-waves (FFRW), and antegrade or retrograde p-waves.

69. The method of claim 50, wherein providing the first input or first output further comprises providing at least one of sensed complete memory data dumps, sensed selected memory location uplinks, detected re-transmissions in a noisy environment, sensed telemetry distance, transmission power, receiver sensitivity, bit error rate (BER), and the amount of data telemetered or received.

70. The method of claim 50, wherein providing the first input or first output further comprises providing at least one of a sampling rate, an activity rate response signal, a cardiac acceleration signal, and an oxygen saturation signal.

71. The method of claim 50, wherein providing the first input or first output further comprises providing sensed intra-circuit block activity per unit time.

72. The method of claim 50, wherein providing the first input or first output further comprises providing at least one of a sensed number of operand codes processed per unit time and a sensed type of operand codes processed per unit time.

73. The method of claim 50, wherein providing the first input or first output further comprises providing at least one of sensed telemetry data format, sensed telemetry data movement, sensed Direct Memory Access (DMA) of an intra-cardiac electrogram, sensed analog-to-digital converter sample rate, and sensed analog-to-digital converter conversion rate.

74. The method of claim 50, wherein providing the first input or first output further comprises providing at least one of sensed activity along a bus, sensed activity within a controller, sensed activity within a microcontroller sensed activity within a microprocessor, and sensed activity within a digital signal processor.

75. The method of claim 50, wherein providing the first input or first output further comprises providing at least one of a timed wakeup, an alarmed wakeup, a sensed interrupt for rate response calculation, a sensed completion of a diagnostic enable window, and a sensed acquisition of diagnostic data.

76. The method of claim 50, wherein providing the processing device further comprises providing at least one of a microprocessor, a microcomputer, a controller, a microcontroller, a digital signal processor, a CPU and an Application Specific Integrated Circuit (ASIC).

77. The method of claim 50, wherein the monitor circuit comprises a device selected from the group consisting of a microprocessor, a microcomputer, a controller, a microcontroller, a digital signal processor, a CPU, and an Application Specific Integrated Circuit (ASIC).

78. The method of claim 50, wherein providing the monitor circuit further comprises providing an adaptive control algorithm for execution thereby.

79. The method of claim 78, wherein providing the adaptive control algorithm further comprises providing the program to permit at least some operating parameters of the medical device to be adjusted on the fly on the basis of the measured, sensed or detected first input or first output.

80. The method of claim 50, wherein the monitor circuit further measures, senses or detects data moving along at least one data bus.

81. The method of claim 50, further comprising programming the monitor circuit.

82. The method of claim 50, further comprising programming the monitor with an adaptive control algorithm.

83. The method of claim 50, wherein providing the monitor circuit further comprises providing a programmable digital signal processor capable of having an adaptive control algorithm programmed therein.

84. The method of claim 83, wherein the digital signal processor is further capable of carrying out adaptive filtering on the measured, sensed or detected first input or first output.

85. The method of claim 83, wherein the digital signal processor is programmable to be capable of discriminating between or detecting at least one of supraventricular tachycardia (SVT), atrial fibrillation (AF), atrial flutter (AFL), ventricular tachycardia (VT), ventricular fibrillation (VF), ventricular flutter (VFL), premature atrial contractions (PAC'"'"'s), premature ventricular contractions (PVC'"'"'s), signal-to-noise ratio of intrinsic cardiac signals, electromagnetic interference (EMI) and myopotentials.

86. The method of claim 50, further comprising providing a clock source for providing clock signals at a plurality of clock frequencies, the clock source being operatively connected to control the at least one circuit at a clock frequency such that substantially the entire predetermined time period is used to perform the at least one function, the function being completed just prior to the subsequent time period.

87. The method of claim 86, wherein providing the at least one circuit further comprises providing at least a first logic circuit for performing a first function and providing a second logic circuit for performing a second function, the first logic circuit being operable to perform the first function during a first predetermined time period and the second logic circuit being operable to perform the second function during a second predetermined time period, each of the first and second logic circuits being operated at a different clock frequency such that substantially the entire respective first and second predetermined time periods are used by the respective first and second logic circuits to perform the respective first and second functions.

88. The method of claim 87, wherein the first predetermined time period and the second predetermined time period are time periods based on physiological events.

89. The method of claim 88, wherein at least one of the first and second time periods is a time period associated with a cardiac event and is selected from the group consisting of a blanking interval, an upper rate interval, an escape interval, a refractory interval, and a pulse generator/programmer handshake.

90. The method of claim 50, wherein the processing device is operable to perform a plurality of functions, each of the plurality of functions being performed during an associated predetermined time period prior to a subsequent time period in which another of the plurality of functions is performed, the processing device being operable to perform each of two or more functions of the plurality of functions at a different clock frequency such that substantially the entire associated predetermined time period for each function is used to perform the functions prior to the subsequent time period in which another of the plurality of functions is performed.

91. The method of claim 90, wherein the associated predetermined time periods are time periods based on physiological events.

92. The method of claim 91, wherein at least one of the associated time periods is a time period associated with a cardiac event and is selected from the group consisting of a blanking interval, an upper rate interval, an escape interval, a refractory interval, and a pulse generator/programmer handshake.

93. The method of claim 50, wherein the first and second voltages are applied to the first and second portions of the at least one circuit as a function of the clock frequency applied to the at least one circuit.

94. The method of claim 93, wherein providing the at least one circuit comprises providing at least a first logic circuit for performing a first function and providing a second logic circuit for performing a second function, wherein each of the first and second logic circuits is operated at a different clock frequency, and further wherein the first and second logic circuits have the first and second supply voltages applied thereto, respectively, based on the different clock frequencies used to control the first and second logic circuits.

95. The method of claim 50, wherein the processing device is operable to perform a plurality of functions, each of at least two of the plurality of functions is performed at a different clock frequency, and the supply voltage applied to the processing device by the one or more voltage sources is adjusted such that the first supply voltage is provided to the processing device during performance of one of the at least two functions and a second supply voltage is provided to the processing device during performance of the other function, wherein the first and second supply voltages are applied to the processing device based on the different clock frequencies used to control the processing device.

96. The method of claim 50, further comprising:

providing a multiplexer for receiving a plurality of analog signals; and

providing an analog to digital converter for converting one or more of the analog signals to digital signals and applying such digital signals to the processing device.