Isolator with integral transformer

• US 9,508,485 B1
• Filed: 01/14/2015
• Issued: 11/29/2016
• Est. Priority Date: 10/04/2012
• Status: Active Grant

• Current Assignee: Vicor Corporation
• Original Assignee: VLT Incorporated (Vicor Corporation)
• Inventors: Vinciarelli, Patrizio
• Primary Examiner(s): PERT, EVAN T
• Application Number:
  US14/596,836
• Time in Patent Office: 685 Days
• US Class Current: 1/1
• CPC Class Codes: H01F 2019/085 Transformer for galvanic isolation
• CPC Class Codes: H01F 2027/2809 on stacked layers
• CPC Class Codes: H01F 27/2804 Printed windings
• CPC Class Codes: H01F 27/288 Shielding
• CPC Class Codes: H01L 2224/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 2924/19105 in a side-by-side arrangement on a common die mounting substrate
• CPC Class Codes: H04L 25/0266 Arrangements for providing Galvanic isolation, e.g. by means of magnetic or capacitive coupling
• CPC Class Codes: H05K 1/0239 Signal transmission by AC coupling
• CPC Class Codes: H05K 1/0254 High voltage adaptations; Electrical insulation details; Overvoltage or electrostatic discharge protection electrostatic discharge protection for electric apparatus in general H05K9/0067, H05K9/0079; Arrangements for regulating voltages or for using plural voltages
• CPC Class Codes: H05K 1/0298 Multilayer circuits
• CPC Class Codes: H05K 1/145 Arrangements wherein electric components are disposed between and simultaneously connected to two planar printed circuit boards, e.g. Cordwood modules
• CPC Class Codes: H05K 1/165 incorporating printed inductors
• CPC Class Codes: H05K 2201/09063 Holes or slots in insulating substrate not used for electrical connections
• CPC Class Codes: H05K 2201/10189 Non-printed connector
• CPC Class Codes: H05K 3/366 substantially perpendicularly to each other H05K3/361 takes precedence

Abstract

A signal isolator apparatus includes a first substrate for supporting input circuitry including a high frequency oscillator circuit for receiving an input signal, a second substrate for supporting output circuitry including a detector circuit for providing an output signal; and a third substrate having parallel conductive layers separated by insulation. The third substrate has an upper conductive shield formed in a second conductive layer and a lower conductive shield formed in a fifth conductive layer. A transformer is formed between the upper and lower conductive shields and includes a primary winding formed in a third conductive layer and a secondary winding formed in a fourth conductive layer. The oscillator circuit is connected to the primary winding and adapted to excite the primary winding at a first frequency in response to the input signal, and the detector circuit is connected to the secondary winding and adapted to selectively sense the first frequency and provide the output signal. The third substrate is arranged to form a bridge connection between the first and second substrates.

Claims

1. An apparatus comprising:

a bridge board comprising a multilayer substrate having a plurality of conductive layers separated by insulation and having a length, a set of A-side contacts located near an end of the bridge board on a first side of an isolation boundary, the isolation boundary dividing the length, and a set of B-side contacts located on a second side of the isolation boundary near an opposite end of the bridge board, the set of B-side contacts being separated by a predetermined distance from the A-side contacts;

the bridge board including one or more transformers, each transformer including an A-side winding connected to the A-side contacts and a B-side winding connected to the B-side contacts;

each A-side winding being galvanically isolated from each B-side contact and each B-side winding;

each B-side winding being galvanically isolated from each A-side contact and each A-side winding;

each A-side and B-side winding being formed in a respective conductive layer of the bridge board and being located in a region providing space for a magnetic field coupling the A-side and B-side windings;

the bridge board being constructed and arranged to span a separation distance between an external A-side circuit having a set of A-side terminals located in an A-side area on a printed circuit board (PCB) and an external B-side circuit having a set of B-side terminals located in a B-side area on a PCB, with the A-side contacts of the bridge board aligned and mated with respective ones of the A-side terminals and the B-side contacts of the bridge board aligned and mated with respective ones of the B-side terminals;

the bridge board providing a galvanically isolated mechanism for connecting the external A-side circuit to the external B-side circuit.

2. The apparatus of claim 1 wherein the one or more transformers comprise a plurality of transformers generally arranged in-line along the length and located in a mid-portion of the bridge board, the A-side windings of the transformers are formed in one conductive layer of the bridge board, and the B-side windings are formed in a second conductive layer of the bridge board.

3. The apparatus of claim 1 wherein the one or more transformers comprise three transformers, the A-side windings of the transformers are formed in one conductive layer of the bridge board, and the B-side windings are formed in a second conductive layer of the bridge board.

4. The apparatus of claim 1 wherein the at least one conductive shield comprises a first conductive shield formed in a third conductive layer and electrically connected to a respective one of the A-side or B-side contacts.

5. The apparatus of claim 4 wherein the at least one conductive shield comprises a second conductive shield formed in a fourth conductive layer and electrically connected to a respective one of the A-side or B-side contacts.

6. The apparatus of claim 5 wherein the bridge board comprises a fifth conductive layer in which the A side and B-side contacts are formed.

7. The apparatus of claim 6 wherein the A-side and B-side contacts are conductive pads exposed on an external surface of the bridge board.

8. The apparatus of claim 6 wherein the conductive layers of the bridge board are arranged in the following sequence:

third conductive layer, first conductive layer, second conductive layer, fourth conductive layer, and fifth conductive layer.

9. The apparatus of claim 1 wherein the isolation boundary between the A-side windings and the B-side windings comprises a layer of insulating material between the first and second conductive layers.

10. The apparatus of claim 1 wherein the at least one conductive shield comprises an A-side shield and a B-side shield and the multi-layer printed circuit board comprises the following layers in sequence:

a third conductive layer in which the A-side shield is formed;

a first conductive layer in which the A-side windings are formed;

a second conductive layer in which the B-side windings are formed;

a fourth conductive layer in which the B-side shield is formed;

a fifth conductive layer in which the A-side and B-side contacts are formed;

and wherein the conductive layers being separated from adjacent conductive layers by at least one intervening insulation layer.

11. The apparatus of claim 1 wherein the at least one conductive shield comprises one or more shorted turns aligned with a respective one of the one or more transformers, and the multi-layer printed circuit board comprises the following layers:

a first conductive layer in which the A-side windings are formed;

a second conductive layer in which the B-side windings are formed;

a fifth conductive layer in which the A-side and B-side contacts are formed;

a sixth conductive layer in which the one or more shorted turns formed;

and wherein the conductive layers are separated from adjacent conductive layers by at least one intervening insulation layer.

12. The apparatus of claim 11 wherein the sixth conductive layer is located on an external surface of the PCB.

13. The apparatus of claim 11 wherein A-side windings and B-side windings each comprises an outer winding diameter and the one or more shorted turns each comprises an outer shorted turn diameter, and the outer shorted turn diameter of each shorted turn is less than the outer winding diameter of at least one of its respective A-side or B-side winding.

14. The apparatus of claim 11 wherein a respective one of the one or more shorted turns is aligned with the A-side winding and B-side winding of each of the one or more transformers.

15. The apparatus of claim 1 further comprising:

a first printed circuit board including the external A-side circuit and a first driver circuit, the first driver circuit having an input for receiving a first input signal from the external A-side circuit and an output connected to the A-side terminals for making electrical connection with a first A-side winding through respective A-side contacts, the first driver circuit being configured to excite the respective A-side winding with a first frequency;

the external B-side circuitry separated from the external A-side circuitry by the separation distance;

a first detector circuit located near the external B-side circuit, the first detector circuit having an output for providing an output signal to the external B-side circuit and an input connected to the B-side terminals for making electrical connection with a first B-side winding through respective B-side contacts, the first detector circuit being configured to selectively sense the first frequency and provide the output signal in response to the first driver circuit exciting the first A-side winding with the first frequency.

16. The apparatus of claim 15 wherein the external B-side circuit and the first detector circuit are located on a second printed circuit board.

17. The apparatus of claim 15 wherein the external B-side circuit and the first detector circuit are located on the first printed circuit board.

18. The apparatus of claim 16 further comprising a power processing module having input terminals, output terminals, and a length, a width, and a height;

wherein the power processing module is arranged between the first printed circuit board and the second printed circuit board and the bridge board is arranged alongside the power processing module extending between the first circuit board and the second printed circuit board.

19. The apparatus of claim 18 wherein the bridge board is substantially perpendicular to the first or second PCB.

20. The apparatus of claim 19 wherein the first and second PCBs are substantially parallel to each other.

21. The apparatus of claim 18 wherein the bridge board and the first or second PCB form an oblique angle.

22. The apparatus of claim 21 wherein the first and second PCBs are substantially parallel to each other.

23. The apparatus of claim 1 further comprising:

a first driver circuit including at least one electronic component mounted to a surface of the bridge board on the A-side of the isolation boundary, the first driver circuit having an input connected to the A-side contacts for receiving an input signal from the external A-side circuit and an output connected to the A-side winding of a first one of the one or more transformers to excite it with a first frequency.

24. The apparatus of claim 1 further comprising:

a first detector circuit including at least one electronic component mounted to a surface of the bridge board on the B-side of the isolation boundary, the first detector circuit having an input connected to the B-side winding of a first of the one or more transformers and an output connected to the B-side contacts for providing an output signal to the B-side external circuit.

25. The apparatus of claim 1 further comprising:

a first driver circuit including at least one electronic component mounted to a surface of the bridge board on the A-side of the isolation boundary, the first driver circuit having an input connected to the A-side contacts for receiving an input signal and an output connected to the A-side winding of a first of the one or more transformers for stimulating the A-side winding with a first frequency;

a first detector circuit including at least one electronic component mounted to a surface of the bridge board on the B-side of the isolation boundary, the first detector circuit having an input connected to the B-side winding of the first transformer and an output connected to the B-side contacts for providing an output signal, the first detector circuit being configured to selectively sense the first frequency and provide the output signal in response to the first driver circuit exciting the first transformer with the first frequency.

26. The apparatus of claim 25 wherein the at least one component of the driver circuit and the at least one component of the detector circuit are mounted to the same surface of the bridge board.

27. The apparatus of claim 1 wherein the A-side contacts and B-side contacts are located on the same surface of the bridge board.

28. The apparatus of claim 1 wherein the A-side contacts and B-side contacts are located on opposite surfaces of the bridge board.

29. The apparatus of claim 1 wherein the A-side or B-side terminals comprise contact fingers configured to mate with respective A-side or B-side contacts on the bridge board.

30. The apparatus of claim 15 wherein the first PCB is positioned within a first plane and the bridge board is positioned within a second plane at an angle to the first plane.

31. The apparatus of claim 30 wherein the angle is approximately 90 degrees.

32. The apparatus of claim 1 wherein the conductive shield comprises a conductive material applied to a surface of the multilayer printed circuit board.

33. The apparatus of claim 15 wherein the A-side or B-side terminal further comprises contact fingers configured to mate with respective A-side or B-side contacts on the bridge board and the bridge board further comprises a contour including at least one feature adapted to form a predetermined alignment between the bridge board and the first PCB.

34. The apparatus of claim 15 wherein the first driver circuit further comprises an oscillator powered exclusively by power received from the first input signal.

35. The apparatus of claim 15 wherein the first detector circuit is powered exclusively by power received from the first B-side winding.

36. The apparatus of claim 15 wherein the first detector circuit is powered exclusively by power received from the first driver circuit through the first transformer, and the first driver circuit is powered exclusively by power received from the first input signal.

37. The apparatus of claim 15 wherein the first driver circuit further comprises an oscillator adapted to excite the first A-side winding with amplitude modulated as a function of the first input signal.

38. The apparatus of claim 37 wherein the first detector circuit is adapted to provide an analog output signal having an amplitude that is a function of the amplitude of the excitation.

39. The apparatus of claim 15 wherein the first detector circuit includes an open-collector output.

40. The apparatus of claim 15 wherein the first detector circuit sinks a current as the output signal.

41. The apparatus of claim 15 wherein the first detector circuit is adapted to provide a binary output signal having a state that is a function of the presence or absence of the excitation.

42. The apparatus of claim 35 wherein the first detector circuit includes an open-collector output.

43. The apparatus of claim 35 wherein the first detector circuit sinks a current as the output signal.

44. The apparatus of claim 1 wherein the region is free of magnetically permeable material.

45. The apparatus of claim 1 wherein the one or more transformers are loosely coupled.

46. The apparatus of claim 45 wherein the one or more transformers is characterized by a coupling coefficient between the windings that is less than 60%.

47. The apparatus of claim 45 wherein the transformer is characterized by a coupling coefficient between the windings that is less than 35%.

48. The apparatus of claim 1 wherein:

the one or more transformers comprise a first transformer and a second transformer, respectively comprising first and second A-side and B-side windings;

the at least one conductive shield is formed in one or more conductive layers of the multi-layer printed circuit board; and

wherein the apparatus further comprises;

a first printed circuit board including the external A-side circuit and A-side terminals;

a second printed circuit board including the external B-side circuit and B-side terminals;

the second printed circuit board being separated by a first distance from the first printed circuit board;

a first driver circuit having an input for receiving a first input signal from the external A-side circuit and an output connected to the first A-side winding, the first driver circuit being configured to excite the first A-side winding with a first frequency;

a first detector circuit having an output for providing an output signal to the external B-side circuit and an input connected to the first B-side winding, the first detector circuit being configured to selectively sense the first frequency and provide the output signal in response to the first driver circuit exciting the first A-side winding with the first frequency;

a second driver circuit having an input for receiving a second input signal from the external B-side circuit and an output connected to the second B-side winding, the second driver circuit being configured to excite the second B-side winding with a second frequency;

a second detector circuit having an output for providing an output signal to the external A-side circuit and an input connected to the second A-side winding, the second detector circuit being configured selectively to sense the second frequency and provide the output signal in response to the second driver circuit exciting the second B-side winding with the second frequency.

49. The apparatus of claim 48 wherein the first driver and second detector are located on the first PCB and the second driver and the first detector are located on the second PCB.

50. The apparatus of claim 48 wherein the first and second drivers and the first and second detectors are located on the multilayer printed circuit board.

51. The apparatus of claim 48 wherein the first driver circuit is powered exclusively by power received from the first input signal.

52. The apparatus of claim 48 wherein the first detector circuit is powered exclusively by power received through the first transformer.

53. The apparatus of claim 1 in which the multilayer substrate comprises a rigid printed circuit board or a flexible circuit.

54. The apparatus of claim 1 in which the A-side circuit and the B-side circuit are located on a same printed circuit board.

55. The apparatus of claim 1 in which the A-side circuit is located on a first printed circuit board, and the B-side circuit is located on a second printed circuit board that is separated from the first printed circuit board.

56. The apparatus of claim 1 in which the A-side contacts of the bridge board are removably mated with respective ones of the A-side terminals, and the B-side contacts of the bridge board are removably mated with respective ones of the B-side terminals.

57. The apparatus of claim 1 in which the A-side contacts of the bridge board are soldered to respective ones of the A-side terminals, and the B-side contacts of the bridge board are soldered to respective ones of the B-side terminals.

58. The apparatus of claim 1 in which the bridge board comprises at least one conductive shield.

59. An apparatus comprising:

an A-side printed circuit board having a set of A-side terminals;

a B-side printed circuit board having a set of B-side terminals; and

a bridge board comprising a multilayer substrate having a plurality of conductive layers separated by insulation and having a set of A-side contacts located near a first end of the bridge board, and a set of B-side contacts located near a second end of the bridge board, the set of B-side contacts being separated by a distance from the A-side contacts, the A-side contacts of the bridge board aligned and mated with respective ones of the A-side terminals, the B-side contacts of the bridge board aligned and mated with respective ones of the B-side terminals;

the bridge board including an A-side winding connected to the A-side contacts and a B-side winding connected to the B-side contacts;

wherein the A-side winding is galvanically isolated from the B-side contacts and the B-side winding, the B-side winding is galvanically isolated from the A-side contacts and the A-side winding; and

wherein each A-side and B-side winding is formed in a respective conductive layer of the bridge board and located in a region providing space for a magnetic field coupling the A-side winding and the B-side winding.

60. The apparatus of claim 59, in which the A-side circuit board comprises a driver circuit, the driver circuit having an input for receiving an input signal from an external A-side circuit and an output connected to the A-side terminals for making electrical connection with the A-side winding through respective A-side contacts, the driver circuit being configured to excite the A-side winding with a first frequency.

61. The apparatus of claim 60 in which the B-side circuit board comprises a detector circuit having an output for providing an output signal to an external B-side circuit and an input connected to the B-side terminals for making electrical connection with a B-side winding through respective B-side contacts, the detector circuit being configured to selectively sense the first frequency and provide the output signal in response to the driver circuit exciting the A-side winding with the first frequency.

62. The apparatus of claim 60, further comprising a power processing module having input terminals and output terminals, in which the power processing module is arranged between the A-side circuit board and the B-side circuit board, and the bridge board is arranged alongside the power processing module extending between the A-side circuit board and the B-side circuit board.

63. The apparatus of claim 60 in which the A-side circuit board and the B-side circuit board are connected as an integral piece.

64. The apparatus of claim 59 wherein the at least one conductive shield comprises one or more shorted turns formed in a conductive layer of the PCB and aligned with at least one of the A-side or B-side windings and the region is bounded on at least one end by the one or more shorted turns.

65. The apparatus of claim 59 wherein the at least one conductive shield comprises a first conductive shield formed in a conductive layer of the PCB and a second conductive shield formed in a conductive layer of the PCB, and the region is bounded between the first and second conductive shields.

66. A method of providing galvanic isolation for one or more signals, the method comprising:

providing a bridge board for supporting isolator circuitry, the bridge board comprising a substrate and a plurality of parallel conductive layers separated by insulation, the bridge board having an A-side winding in a first conductive layer of the substrate and a B-side winding in a second conductive layer of the substrate;

coupling the bridge board to an A-side printed circuit board (PCB) that has a driver circuit having an input for receiving an input signal and an output electrically coupled to the A-side winding;

coupling the bridge board to a B-side PCB that has a detector circuit having an input for receiving a signal from the B-side winding;

exciting, using the driver circuit, the A-side winding at a first frequency in response to the input signal;

selectively sensing, using the detector circuit, the first frequency at the B-side winding; and

providing an output signal at an output of the B-side circuit board in response to sensing the first frequency.

67. The method of claim 66 in which exciting the A-side winding at a first frequency comprises exciting the A-side winding at a first frequency using power derived from the input signal.

68. The method of claim 67 in which providing an output signal comprises providing an output signal at an output of the B-side circuit board using power derived from the B-side winding.

69. The method of claim 66 further comprising providing one or more shorted turns to create a region for the windings to reduce effects from extraneous magnetic fields.

70. The method of claim 66 further comprising providing one or more conductive shields to create a region for the windings to reduce effects from extraneous magnetic fields.

71. A method of providing galvanic isolation for one or more signals, the method comprising:

using a driver circuit on an A-side printed circuit board (PCB) to drive an A-side winding in a bridge board coupled to the A-side PCB at a first frequency, the bridge board having A-side contacts that are coupled to A-side terminals on the A-side PCB, the A-side contacts being electrically coupled to the A-side winding;

using a detector circuit on a B-side PCB to selectively sense the first frequency at a B-side winding in the bridge board, the bridge board having B-side contacts that are coupled to B-side terminals on the B-side PCB, the B-side contacts being electrically coupled to the B-side winding; and

generating an output signal at an output of the B-side circuit board in response to sensing the first frequency.

72. The method of claim 71 in which exciting the A-side winding at a first frequency comprises exciting the A-side winding at a first frequency using power derived from an input signal received at an input of the A-side circuit board.

73. The method of claim 72 in which providing an output signal comprises providing an output signal at an output of the B-side circuit board using power derived from the B-side winding.

74. The method of claim 71 in which the A-side contacts are removably coupled to the A-side terminals on the A-side PCB and the B-side contacts are removably coupled to the B-side terminals on the B-side PCB.

75. The method of claim 71 in which the A-side contacts are soldered to the A-side terminals on the A-side PCB and the B-side contacts are soldered to the B-side terminals on the B-side PCB.