Simplified defibrillator output circuit

• US 20030088283A1
• Filed: 11/05/2001
• Published: 05/08/2003
• Est. Priority Date: 11/05/2001
• Status: Active Grant

• Current Assignee: Cameron Incorporated (Schlumberger NV)
• Original Assignee: Cameron Incorporated (Schlumberger NV)
• Inventors: Ostroff, Alan H.
• Granted Patent: US 6,954,670 B2
• Time in Patent Office: Days
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3912 Output circuitry therefor, e.g. switches
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion

Abstract

High side driver circuitry for a defibrillator circuit employs respective capacitors connected to respective gates of silicon controlled rectifiers serving as high side switches. Applying a voltage pulse to a selected capacitor turns on the associated SCR. Positive turn-on of the high side SCRs is insured by inserting a constant current source into the low side activation current path at start-up.

Claims

1. A defibrillator circuit comprising:

a first high side switching device having a control terminal adapted to receive a control current, said control current causing closing of a signal path through said switching device; and

a first capacitor coupled to said control terminal and adapted to receive a control voltage selected to create said control current.

2. The circuit of claim 1 wherein said first high side switching device comprises a first silicon controlled rectifier.

3. The circuit of claim 1 wherein said control terminal is the gate of a first silicon controlled rectifier.

4. The circuit of claim 1 further including a current source located in said circuit and selectively activatable for holding said silicon controlled rectifier “

on”

during a selected interval.

5. The circuit of claim 4 wherein said current source is connected to a leg of a low side switch of said circuit.

6. The circuit of claim 1 further including a second high side switching device having a control terminal adapted to receive a control current, said control current causing closing of a signal path through said switching device.

7. The circuit of claim 6 further including a second capacitor coupled to the control terminal of said second high side switching device and adapted to receive a control voltage selected to create said current.

8. The circuit of claim 7 wherein said second high side switching device comprises a second silicon controlled rectifier.

9. The circuit of claim 8 wherein said first and second silicon controlled rectifiers each have a respective terminal connected to apply a voltage across a patient.

10. The circuit of claim 9 further including a drive circuit adapted to apply a drive voltage to each of said first and second silicon controlled rectifiers.

11. The circuit of claim 10 wherein said drive voltage is applied to respective anodes of the first and second silicon controlled rectifiers.

12. The circuit of claim 9 wherein respective anodes of the first and second silicon controlled rectifiers are adapted to apply said voltage across said patient.

13. The circuit of claim 10 further including first and second low side switches, the first low side switch having a first leg connected to said first silicon controlled rectifier, said second low side switch having a leg connected to said second silicon controlled rectifier.

14. The circuit of claim 13 further including means for causing a current to pass through said first silicon controlled rectifier to said patient and from said patient through said second switch.

15. The circuit of claim 13 further including means for causing a current to pass through said second silicon controlled rectifier to said patient and from said patient through said first switch.

16. The circuit of claim 14 wherein said means includes means for generating a current to positively hold “

on”

said first silicon controlled rectifier.

17. The circuit of claim 16 wherein said means for generating a current comprises a constant current source.

18. The circuit of claim 15 wherein said means for causing a current to pass through said second silicon controlled rectifier includes means for generating a current to positively hold “

on”

said first silicon controlled rectifier.

19. The circuit of claim 18 wherein said means for generating comprises a constant current source.

38. The method of claim 13 wherein said first and second low side switches each comprise one of a (a) silicon controller rectifier, (b) MOSFET, or (c) IGBT.

40. The apparatus of claim 1 wherein said defibrillator circuit forms part of a subcutaneous only implantable cardioverter-defibrillator.

20. A method of controlling high side switching in a defibrillation circuit comprising:

employing a first silicon controlled rectifier having a gate as a high side switching component; and

employing a first device coupled to said gate to create a current into said gate.

21. The method of claim 20 wherein said first device comprises a capacitor.

22. The method of claim 20 further including the step of employing a second silicon controlled rectifier as a second high side switching device and employing a second device coupled to said gate to create a current into said gate.

23. The method of claim 20 wherein each of said first and second silicon controlled rectifiers have a control terminal adapted to receive a control current, said control current causing closing of a signal path through the respective rectifier.

24. The method of claim 22 further wherein said second device comprises a capacitor.

25. The method of claim 22 wherein said first and second silicon controlled rectifiers each have a respective terminal connected to apply a voltage across a patient.

26. The method of claim 25 further including the step of applying a drive voltage to each of said first and second silicon controlled rectifiers.

27. The method of claim 26 wherein said drive voltage is applied to respective anodes of the first and second silicon controlled rectifiers.

28. The method of claim 27 wherein the respective anodes of the first and second silicon controlled rectifiers are adapted to apply said voltage across said patient.

29. The method of claim 22 further including the step of employing first and second low side switches, the first low side switch having a first leg connected to said first silicon controlled rectifier, the second low side switch having a leg connected to said second silicon controlled rectifier.

30. The method of claim 29 further including the step of causing a current to pass through said first silicon controlled rectifier to said patient and from said patient through said second switch.

31. The method of claim 29 further including the steps of causing a current to pass through said second silicon controlled rectifier to said patient and from said patient through said second switch.

32. The method of claim 30 further including the step of generating a current to positively hold “

on”

said first silicon controlled rectifier.

33. The method of claim 20 further including the step of generating a current to positively hold “

on”

said first silicon controlled rectifier.

34. The method of claim 32 wherein a constant current source is used to generate said current.

35. The method of claim 33 wherein a constant current source is used to generate said current.

41. The method of claim 20 wherein said defibrillator circuit forms part of a subcutaneous only implantable cardioverter-defibrillator.

36. In a defibrillator circuit, the method comprising:

using first and second silicon controlled rectifiers as high side switch devices; and

employing capacitors cross-coupled to respective low side switching devices to switch “

on”

the respective silicon controlled rectifiers.

42. The method of claim 36 wherein said defibrillator circuit forms part of a subcutaneous only implantable cardioverter-defibrillator.

37. In a defibrillator circuit, the method comprising:

using first and second silicon controlled rectifiers as high side switching devices; and

applying a switching signal to the respective gates of each of said first and second silicon controlled rectifiers through a first and second capacitors respectively coupled to said gates.

39. The circuit of claim 37 wherein said first and second devices each comprise a capacitor.