di/dt Current Sensing

• US 20120068691A1
• Filed: 09/22/2010
• Published: 03/22/2012
• Est. Priority Date: 09/22/2010
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies North America Corporation (Infineon Technologies AG)
• Inventors: Ejury, Jens
• Granted Patent: US 8,981,763 B2
• Time in Patent Office: Days
• US Class Current: 324/103.R
• CPC Class Codes: G01R 15/181 using coils without a magnetic core, e.g. Rogowski coils
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• CPC Class Codes: H01F 19/04 Transformers or mutual inductances suitable for handling frequencies considerably beyond the audio range resonant circuits H03H
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter

Abstract

A circuit includes a power circuit and a current sensing circuit. The power circuit has a main current loop. The current sensing circuit is spaced apart from and electrically decoupled from the power circuit. The current sensing circuit is operable to generate a voltage proportional to an electromagnetic field generated responsive to a current change in the main current loop of the power circuit and generate a current information signal based on the voltage. The current information signal describes the current in the main current loop.

Claims

1. A circuit, comprising:

a power circuit having a main current loop; and

a current sensing circuit spaced apart from and electrically decoupled from the power circuit, the current sensing circuit operable to generate a voltage proportional to an electromagnetic field generated responsive to a current change in the main current loop of the power circuit and generate a current information signal based on the voltage, the current information signal describing the current in the main current loop.

2. The circuit of claim 1, wherein the current sensing circuit comprises:

a conductive loop spaced apart from the power circuit and disposed over at least a portion of the main current loop, the conductive loop electrically decoupled from the power circuit and operable to generate the voltage proportional to the electromagnetic field;

a rectifier coupled to the conductive loop and operable to rectify the voltage generated by the conductive loop; and

a capacitor coupled to the rectifier and operable to accumulate charge responsive to the rectified voltage, wherein a voltage across the capacitor is related to the current in the main current loop.

3. The circuit of claim 2, wherein the rectifier comprises a plurality of silicon rectifier diodes coupled together to form a bridge rectifier, each of the plurality of silicon rectifier diodes having a negative forward voltage temperature coefficient.

4. The circuit of claim 2, wherein the current sensing circuit comprises a switch device coupled to the capacitor and operable to periodically reset the capacitor responsive to a reset signal.

5. The circuit of claim 4, wherein the switch device is operable to permit the capacitor to integrate the rectified voltage over a plurality of sampling periods prior to resetting the capacitor.

6. The circuit of claim 2, wherein the current sensing circuit comprises an analysis circuit operable to compare the voltage across the capacitor to a plurality of thresholds and generate the current information signal based on which of the plurality of thresholds the voltage exceeds.

7. The circuit of claim 6, wherein the analysis circuit comprises at least one of an analog-to-digital converter, an amplifier and a trigger circuit.

8. The circuit of claim 6, wherein the analysis circuit is operable to analyze the voltage across the capacitor over a plurality of sampling periods and smooth the current information signal over the plurality of sampling periods.

9. The circuit of claim 1, further comprising a controller operable to control a current dependent operation of the power circuit based on the current information signal.

10. A method of operating a circuit including a power circuit with a main current loop and a current sensing circuit spaced apart from and electrically decoupled from the power circuit, the method comprising:

generating an electromagnetic field by the power circuit responsive to a current change in the main current loop of the power circuit;

generating a voltage by the current sensing circuit that is proportional to the electromagnetic field; and

generating a current information signal by the current sensing circuit based on the voltage, the current information signal describing the current in the main current loop.

11. The method of claim 10, comprising:

generating the voltage to the electromagnetic field by a conductive loop of the current sensing circuit that is spaced apart from the power circuit, disposed over at least a portion of the main current loop, and electromagnetically coupled to at least a portion of the power circuit;

rectifying the voltage generated by the conductive loop; and

accumulating charge in a capacitor responsive to the rectified voltage, wherein a voltage across the capacitor is a function of the change in current in the main current loop.

12. The method of claim 11, comprising periodically resetting the capacitor responsive to a reset signal.

13. The method of claim 12, comprising permitting the capacitor to integrate the rectified voltage over a plurality of sampling periods prior to resetting the capacitor.

14. The method of claim 11, comprising:

comparing the voltage across the capacitor to a plurality of thresholds; and

generating the current information signal based on which of the plurality of thresholds the voltage exceeds.

15. The method of claim 10, comprising controlling a current dependent operation of the power circuit based on the current information signal.

16. An integrated circuit package, comprising:

a power circuit including a plurality of transistors which form part of a main current loop of the power circuit, the plurality of transistors arranged in one or more layers of the integrated circuit package; and

a conductive loop electrically decoupled from the plurality of transistors, the conductive loop being spaced apart from the plurality of transistors and in close enough proximity to at least part of the main current loop so that the conductive loop is operable to generate a voltage proportional to an electromagnetic field generated responsive to a change in current in the main current loop.

17. The integrated circuit package of claim 16, wherein the conductive loop is arranged within the integrated circuit package in a different layer of the integrated circuit package than the plurality of transistors.

18. The integrated circuit package of claim 16, wherein the conductive loop is attached to an external surface of the integrated circuit package.

19. The integrated circuit package of claim 16, further comprising a first external terminal coupled to one end of the conductive loop and a second external terminal coupled to the other end of the conductive loop, the first and second external terminals providing connection points for the conductive loop at an external surface of the integrated circuit package.

20. The integrated circuit package of claim 16, wherein the power circuit includes a first MOSFET and a second MOSFET, the conductive loop is positioned over at least a portion of the first MOSFET and at least a portion of the second MOSFET, and an insulator layer is interposed between the conductive loop and the first and second MOSFETs.

21. The multi-layer integrated circuit package of claim 20, wherein the first MOSFET is a high-side MOSFET of a power converter circuit and the second MOSFET is a low-side MOSFET of the power converter circuit.

22. A method of fabricating an integrated circuit package, comprising:

arranging a power circuit including a plurality of transistors which form part of a main current loop of the power circuit in one or more layers of the integrated circuit package; and

arranging a conductive loop electrically decoupled from and spaced apart from the plurality of transistors, the conductive loop being arranged in close enough proximity to at least part of the main current loop so that the conductive loop is operable to generate a voltage proportional to an electromagnetic field generated responsive to a change in current in the main current loop.

23. The method of claim 22, comprising coupling a first external terminal to one end of the conductive loop and a second external terminal to the other end of the conductive loop so that the first and second external terminals provide connection points for the conductive loop at an external surface of the integrated circuit package.

24. The integrated circuit package of claim 22, comprising:

arranging the conductive loop over first and second MOSFETs of the power circuit; and

interposing an insulator layer between the conductive loop and the first and second MOSFETs.

25. The method of claim 24, comprising positioning the conductive loop over at least a portion of the first MOSFET and at least a portion of the second MOSFET.