Self-Oscillating Power Circuit

• US 20070216491A1
• Filed: 06/27/2003
• Published: 09/20/2007
• Est. Priority Date: 06/27/2003
• Status: Active Grant

• Current Assignee: The TC Group A/S (Music Group Services US Incorporated)
• Original Assignee: The TC Group A/S (Music Group Services US Incorporated)
• Inventors: Pedersen, Kim, Frederiksen, Thomas
• Granted Patent: US 7,391,258 B2
• Time in Patent Office: Days
• US Class Current: 331/167
• CPC Class Codes: H03F 1/08 Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements wide-band amplifiers with inter-stage coupling networks incorporating these impedances H03F1/42
• CPC Class Codes: H03F 2200/78 A comparator being used in a controlling circuit of an amplifier
• CPC Class Codes: H03F 3/217 Class D power amplifiers; Switching amplifiers

Abstract

The invention relates to a self-oscillating circuit comprising comparator means (CM) comprising at least one input means (IM) and at least one output means (OM), at least one of said at least one output means (OM) is coupled to at least one of said at least one input means (IM) via at least one filtering means (FM), said at least one filtering means (FM) at least partly comprising demodulation means (DM), wherein said filtering means (FM) is of at least fifth order.

Claims

1. A self-oscillating circuit comprising comparator means (CM) comprising at least one input means (IM) and at least one output means (OM),

at least one of said at least one output means (OM) is coupled to at least one of said at least one input means (IM) via at least one filtering means (FM),

said at least one filtering means (FM) at least partly comprising demodulation means (DM),

wherein said filtering means (FM) is of at least fifth order.

2. A self-oscillating circuit according to claim 1, wherein a number of filter poles comprised by said filtering means (FM) is at least five.

3. A self-oscillating circuit according to claim 1, wherein a number of filter poles comprised by said filtering means (FM) is at least eight.

4. A self-oscillating circuit according to claim 1, wherein a number of filter poles comprised by said filtering means (FM) is at least eleven.

5. A self-oscillating circuit according to claim 1, wherein a number of filter zeroes comprised by said filtering means (FM) is at least two.

6. A self-oscillating circuit according to claim 1, wherein a number of filter zeroes comprised by said filtering means (FM) is at least five.

7. A self-oscillating circuit according to claim 1, wherein a number of filter zeroes comprised by the characteristic of said filtering means FM is at least eight.

8. A self-oscillating circuit according to claim 1, wherein a number of filter poles comprised by said filtering means (FM) exceeds a number of filter zeroes by three.

9. A self-oscillating circuit according to claim 1, wherein at least one filter zeroes comprised by said filtering means (FM) cancels at least one of said filter poles.

10. A self-oscillating circuit according to claim 9, wherein a location of at least one of said filter zeroes is determined on the basis of a location of at least one of said filter poles.

11. A self-oscillating circuit according to claim 10, wherein the location of each of said filter zeroes is determined on a basis of the locations of said filter poles.

12. A self-oscillating circuit according to claim 1, wherein said self-oscillating circuit oscillates at a switch frequency (f_SW) higher than an upper frequency (f₀) of a utility frequency band.

13. A self-oscillating circuit according to claim 12, wherein said utility frequency band is an audio band.

14. A self-oscillating circuit according to claim 12, wherein said utility frequency band comprises frequencies in a range of 0 Hz to 100 kHz.

15. A self-oscillating circuit according to claim 12, wherein said utility frequency band comprises frequencies in the range of 0 Hz to 60 kHz.

16. A self-oscillating circuit according to claim 12, wherein said utility frequency band comprises frequencies in the range of 20 Hz to 20 kHz.

17. A self-oscillating circuit according to claim 1, wherein said self-oscillating circuit comprises a switch mode amplifier (AM).

18. A self-oscillating circuit according to claim 12, wherein said switch frequency (f_SW) is at least partly determined by means of filter poles and filter zeroes.

19. A self-oscillating circuit according to claim 12, wherein a phase margin of an open loop characteristic for frequencies within a frequency band having a lower frequency of one tenth of said switch frequency (f_SW) and an upper frequency of said switch frequency (f_SW) is between 0°

and 60°

.

20. A self-oscillating circuit according to claim 12, wherein a phase margin of an open loop characteristic for frequencies within a frequency band having a lower frequency of one tenth of said switch frequency (f_SW) and an upper frequency of said switch frequency (f_SW) is between 0°

and 45°

.

21. A self-oscillating circuit according to claim 12, wherein a phase margin of an open loop characteristic for frequencies within a frequency band having a lower frequency of one tenth of said switch frequency (f_SW) and an upper frequency of said switch frequency (f_SW) is between 0°

and 30°

.

22. A self-oscillating circuit according to claim 12, wherein a gain of an open loop characteristic at a frequency of one hundredth of said switch frequency (f_SW) exceeds a gain at said switch frequency (f_SW) by at least 50 dB.

23. A self-oscillating circuit according to claim 12, wherein a gain of an open loop characteristic at a frequency of one hundredth of said switch frequency (f_SW) exceeds a gain at said switch frequency (f_SW) by at least 60 dB.

24. A self-oscillating circuit according to claim 12, wherein a gain of an open loop characteristic at a frequency of one hundredth of said switch frequency (f_SW) exceeds a gain at said switch frequency (f_SW) by at least 70 dB.

25. A self-oscillating circuit according to claim 1, wherein said filtering means (FM) comprises additional auxiliary filter poles or zeroes.

26. A self-oscillating circuit according to claim 12, wherein said upper frequency (f₀) of said utility frequency band is determined as a break frequency of said demodulation means (DM).

27. A self-oscillating circuit according to claim 1, wherein said demodulation means (DM) comprises at least one filter pole.

28. A self-oscillating circuit according to claim 1, wherein said demodulation means (DM) comprises at least two filter poles.

29. A self-oscillating circuit according to claim 1, wherein said filtering means (FM) comprises at least one feedback filtering means (FFM) and at least one compensation filtering means (CFM).

30. A self-oscillating circuit according to claim 1, wherein said self-oscillating circuit comprises at least two feedback paths.

31. A self-oscillating circuit according to claim 1, wherein said self-oscillating circuit comprises a first feedback path comprising at least partly said demodulation means (DM), a first feedback filtering means (FFFM) and a first compensation filtering means (FCFM) and an additional feedback path comprising an additional feedback filtering means (AFFM) and an additional compensation filtering means (ACFM).

32. A self-oscillating circuit according to claim 31, wherein said additional feedback path at least partly comprises said demodulation means (DM).

33. A self-oscillating circuit according to claim 1, wherein said comparator means (CM) comprises a hysteresis comparator.

34. A self-oscillating circuit according to claim 17, wherein said switch mode amplifier (AM) comprises two switches.

35. A self-oscillating circuit according to claim 17, wherein said switch mode amplifier (AM) is a power amplifier.

36. A self-oscillating circuit according to claim 17, wherein said switch mode amplifier (AM) comprises MOSFET transistors.

37. A self-oscillating circuit according to claim 1, wherein said demodulation means (DM) is a low-pass filter.

38. A self-oscillating circuit according to claim 1, wherein said demodulation means (DM) comprises auxiliary circuitry.

39. A self-oscillating circuit according to claim 38, wherein said auxiliary circuitry comprises means for protecting said self-oscillating circuit.

40. A self-oscillating circuit according to claim 38, wherein said auxiliary circuitry comprises a Zobel network.

41. A self-oscillating circuit according to claim 38, wherein said auxiliary circuitry comprises means for impedance matching.

42. A self-oscillating circuit according to claim 12, wherein said switch frequency (f_SW) is comprised by frequency band from 100 kHz to 100 MHz.

43. A self-oscillating circuit according to claim 31, wherein said first feedback filtering means (FFFM) is a high-pass filter.

44. A self-oscillating circuit according to claim 31, wherein said first feedback filtering means (FFFM) comprises a zero at an upper frequency (f₀) of the utility frequency band.

45. A self-oscillating circuit according to claim 31, wherein said first compensation filtering means (FCFM) is a phase-lag filter.

46. A self-oscillating circuit according to claim 31, wherein said first compensation filtering means (FCFM) comprises a pole at a low frequency (f_DC), a zero at an upper frequency (f₀) of the utility frequency band and a pole at a switch frequency (f_SW).

47. A self-oscillating circuit according to claim 31, wherein said additional feedback filtering means (AFFM) is a low-pass filter.

48. A self-oscillating circuit according to claim 31, wherein said additional feedback filtering means (AFFM) comprises a pole at an upper frequency (f₀) of the utility frequency band.

49. A self-oscillating circuit according to claim 31, wherein said additional compensation filtering means (ACFM) is a phase-lag filter.

50. A self-oscillating circuit according to claim 31, wherein said additional compensation filtering means (ACFM) comprises a pole at a low frequency (f_DC), a zero at an upper frequency (f₀) of the utility frequency band and a pole at a switch frequency (f_SW).

51. A self-oscillating circuit according to claim 17, wherein said switch mode amplifier (AM) is of a differential output type.