Minimizing Electromagnetic Interference in Coil Transducers

• US 20090243783A1
• Filed: 02/26/2009
• Published: 10/01/2009
• Est. Priority Date: 08/28/2006
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Fouquet, Julie E., Baumgartner, Richard, Trott, Gary R.
• Granted Patent: US 8,061,017 B2
• Time in Patent Office: Days
• US Class Current: 336/200
• CPC Class Codes: H01F 17/0006 Printed inductances printed coils for dynamo-electric machines H02K3/26; printed circuits H05K
• CPC Class Codes: H01F 17/0013 with stacked layers
• CPC Class Codes: H01F 19/08 Transformers having magnetic bias, e.g. for handling pulses
• CPC Class Codes: H01F 2019/085 Transformer for galvanic isolation
• CPC Class Codes: H01F 2038/143 for signals
• CPC Class Codes: H01F 27/2804 Printed windings
• CPC Class Codes: H01F 27/34 Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
• CPC Class Codes: H01F 27/40 Structural association with built-in electric component, e.g. fuse
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48195 the item being a discrete passive component
• CPC Class Codes: H01L 2224/49111 the connectors connecting two common bonding areas, e.g. Litz or braid wires
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/30107 Inductance
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: H03F 2203/45008 the addition of two signals being made by a resistor addition circuit for producing the common mode signal
• CPC Class Codes: H03F 2203/45101 Control of the DC level being present
• CPC Class Codes: H03F 2203/45586 the IC comprising offset generating means
• CPC Class Codes: H03F 3/45192 Folded cascode stages
• CPC Class Codes: H03F 3/45475 : using IC blocks as the active amplifying circuit
• CPC Class Codes: H04B 5/0093 : with one coil at each side, e.g. with primary and secondary coils
• CPC Class Codes: H04B 5/266 : One coil at each side, e.g. with primary and secondary coils
• CPC Class Codes: H04L 25/0266 : Arrangements for providing Galvanic isolation, e.g. by means of magnetic or capacitive coupling
• CPC Class Codes: Y10T 29/4902 : Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/49071 : by winding or coiling
• CPC Class Codes: Y10T 29/49073 : by assembling coil and core

Abstract

Disclosed herein are various embodiments of means and methods for reducing the pick-up of electromagnetic interference (“EMI”) by coil transducers configured to provide high voltage isolation and high voltage breakdown performance characteristics in small packages. In some embodiments, the lengths, heights, and horizontal distances between wires electrically connecting transmitter circuits and receiver circuits to coil transducers are minimized and optimized respecting one another.

Claims

1. A coil transducer system, comprising:

a coil transducer comprising a generally planar substrate comprising opposing upper and lower surfaces and including therein a dielectric barrier, the dielectric barrier comprising an electrically insulating, non-metallic, non-semiconductor, low-dielectric-loss material, a first electrically conductive coil disposed above the upper surface of the substrate, the first coil extending between first and second coil input terminals disposed at opposite ends thereof, a second electrically conductive coil disposed below the lower surface of the substrate, the second coil extending between first and second output coil terminals disposed at opposite ends thereof, and

a transmitter circuit comprising first and second transmitter output terminals;

wherein a first wire is electrically connected to, and extends between, the first transmitter output terminal and the first input coil terminal, a second wire is electrically connected to, and extends between, the second transmitter output terminal and the second input coil terminal, the first and second wires are substantially parallel to one another or exhibit substantially similar angles respecting a major axis of the coil transducer, the first and second wires have substantially a same first length, the first and second wires thereby being configured to minimize the pick-up of electromagnetic interference (“

EMI”

) thereby.

2. The coil transducer system of claim 1, wherein an angle between the first and second wires does not exceed about fifteen degrees.

3. The coil transducer system of claim 1, wherein the substantially similar angles of the first and second wires each range between about 0 degrees and about 10 degrees with respect to the major axis.

4. The coil transducer system of claim 1, wherein a vertical distance over which the first wire and the second wire extend above the transmitter circuit and the coil transducer is substantially the same and does not exceed about 5 mils.

5. The coil transducer system of claim 1, wherein the first length ranges between about 5 mils and about 30 mils.

6. The coil transducer system of claim 1, wherein a horizontal separation between the first wire and the second wire does not exceed about 15 mils.

7. The coil transducer system of claim 1, further comprising a receiver circuit comprising first and second input receiver terminals.

8. The coil transducer system of claim 7, further comprising a third wire electrically connected to, and extending between, the first receiver input terminal and the first output coil terminal, and a fourth wire electrically connected to, and extending between, the second receiver input terminal and the output terminal of the second coil, the third and fourth wires being substantially parallel to one another, the third and fourth wires having substantially a same third length, the third and fourth wires being configured to minimize the pick-up of electromagnetic interference (“

EMI”

) thereby.

9. The coil transducer system of claim 8, wherein an angle between the third and fourth wires does not exceed about fifteen degrees.

10. The coil transducer system of claim 8, wherein a vertical distance over which the third wire and the fourth wire extend above the receiver circuit and the coil transducer is substantially the same and does not exceed about 5 mils.

11. The coil transducer system of claim 8, wherein the third length ranges between about 5 mils and about 30 mils.

12. The coil transducer system of claim 8, wherein a horizontal separation between the third wire and the fourth wire does not exceed about 15 mils.

13. The coil transducer system of claim 1, wherein at least one of the first coil and the second coil has a trace width not exceeding about 5 mils thereby to minimize the capacitance between the first and second coils.

14. The coil transducer system of claim 1, wherein the first coil and the second coil are not vertically aligned respecting one another thereby to reduce the capacitance between the first and second coils.

15. The coil transducer system of claim 1, wherein the first wire and the second wire together comprise a pair of substantially parallel wires.

16. The coil transducer system of claim 8, wherein the third wire and the fourth wire together comprise a pair of substantially parallel wires.

17. The coil transducer system of claim 1, wherein the transmitter circuit is configured to provide differential output signals across the input terminals of the first coil.

18. The coil transducer system of claim 8, wherein the receiver circuit is configured to receive differential output signals across the output terminals of the second coil.

19. The coil transducer system of claim 1, wherein the first and second coils are spatially arranged and configured respecting one another such that at least one of power and data signals may be transmitted by the first coil to the second coil across the substrate.

20. The coil transducer system of claim 1, wherein the substrate comprises at least one of fiberglass, glass, ceramic, polyimide, polyimide film, a polymer, an organic material, a flex circuit material, epoxy, epoxy resin, a printed circuit board material, PTFE and glass, PTFE and ceramic, glass and ceramic, thermoset plastic, and plastic.

21. The coil transducer system of claim 1, wherein a breakdown voltage between the first coil and the second coil exceeds about 2,000 volts RMS when applied over a time period of about one minute, exceeds about 2,000 volts RMS when applied over a time period of about six minutes, or exceeds about 2,000 volts RMS when applied over a time period of 24 hours.

22. The coil transducer system of claim 1, wherein a breakdown voltage between the first coil and the second coil exceeds about 5,000 volts RMS when applied over a time period of about one minute, exceeds about 5,000 volts RMS when applied over a time period of about six minutes, or exceeds about 5,000 volts RMS when applied over a time period of 24 hours.

23. The coil transducer system of claim 1, further comprising a spacer layer located above the upper surface of the substrate or below the lower surface of the substrate, the spacer layer comprising a low-dielectric-loss material and being configured to minimize the pick-up of EMI by at least some electrically conductive portions of the coil transducer.

24. The coil transducer of claim 23, wherein the spacer layer has a thickness ranging between about 25 mils and about 50 mils.

25. The coil transducer of claim 24, further comprising a metal shield disposed above the spacer layer when the spacer layer is located above the upper surface of the substrate or below the spacer layer when the spacer layer is located below the lower surface of the substrate.

26. The coil transducer system of claim 1, wherein substantially the same low-dielectric-loss materials having substantially the same thicknesses are disposed above or near the upper surface of the substrate and below or near the lower surface of the substrate thereby to present substantially similar environments respecting EMI impinging upon the coil transducer from upward and downward directions.

27. A method of making a coil transducer system, comprising:

forming a coil transducer comprising a generally planar substrate comprising opposing upper and lower surfaces and including therein a dielectric barrier, the dielectric barrier comprising an electrically insulating, non-metallic, non-semiconductor, low-dielectric-loss material, a first electrically conductive coil disposed above the upper surface of the substrate, the first coil extending between first and second coil input terminals disposed at opposite ends thereof, a second electrically conductive coil disposed below the lower surface of the substrate, the second coil extending between first and second output coil terminals disposed at opposite ends thereof, and

providing a transmitter circuit comprising first and second transmitter output terminals;

electrically connecting a first wire between the first transmitter output terminal and the first input coil terminal;

electrically connecting a second wire between the second transmitter output terminal and the second input coil terminal, and

configuring the first and second wires to be substantially parallel to one another, or to exhibit substantially similar angles respecting an azimuth extending along a major axis of the coil transducer, and have substantially a same first length such that the first and second wires are configured to minimize the pick-up of electromagnetic interference (“

EMI”

) thereby.

28. The method of claim 27, further comprising electrically connecting the first and second wires to the coil transducer and the transmitter circuit such that an angle between the first and second wires does not exceed about fifteen degrees.

29. The method of claim 27, further comprising electrically connecting the first and second wires to the coil transducer and the transmitter circuit such that the substantially similar angles thereof each range between about 0 degrees and about 10 degrees with respect to the major axis.

30. The method of claim 27, further comprising extending the first wire and the second wire a vertical distance over the transmitter circuit and the coil transducer that is substantially the same and does not exceed about 5 mils.

31. The method of claim 27, further comprising selecting the first length to range between about 5 mils and about 30 mils.

32. The method of claim 27, further comprising providing a horizontal separation between the first wire and the second wire that does not exceed about 15 mils.

33. The method of claim 27, further comprising providing a receiver circuit comprising first and second input receiver terminals.

34. The method of claim 33, further comprising electrically connecting a third wire between the first receiver input terminal and the first output coil terminal, and electrically connecting a fourth wire between the second receiver input terminal and the output terminal of the second coil, the third and fourth wires being substantially parallel to one another.

35. The method of claim 34, further comprising configuring the third and fourth wires to have substantially a same third length such that the pick-up of electromagnetic interference (“

EMI”

) thereby is minimized.

36. The method of claim 34, further comprising electrically connecting the third and fourth wires to the coil transducer and the transmitter circuit such that an angle between the third and fourth wires does not exceed about fifteen degrees.

37. The method of claim 34, further comprising extending the third wire and the fourth wire a vertical distance over the receiver circuit and the coil transducer that does not exceed about 5 mils.

38. The method of claim 34, further comprising selecting the third length to range between about 5 mils and about 30 mils.

39. The method of claim 34, further comprising providing a horizontal separation between the third wire and the fourth wire that does not exceed about 15 mils.

40. The method of claim 27, further comprising forming at least one of the first coil and the second coil to have a trace width not exceeding about 5 mils thereby to minimize the capacitance between the first and second coils.

41. The method of claim 27, further comprising providing a pair of substantially parallel wires for each of the first wire and the second wire.

42. The method of claim 27, further comprising providing a pair of substantially parallel wires for each of the third wire and the fourth wire.

43. The method of claim 27, further comprising configuring the transmitter circuit to provide differential output signals across the input terminals of the first coil.

44. The method of claim 34, further comprising configuring the receiver circuit to provide differential output signals across the output terminals of the second coil.