Apparatus and method for implementing a differential drive amplifier and a coil arrangement

• US 8,772,975 B2
• Filed: 12/02/2010
• Issued: 07/08/2014
• Est. Priority Date: 12/07/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Tseng, Ryan, Mayo, Gabriel I
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): BUKHARI, AQEEL H
• Application Number:
  US12/959,257
• Publication Number:
  US 20110133570A1
• Time in Patent Office: 1,314 Days
• Field of Search: None
• US Class Current: 307/104
• CPC Class Codes: H03F 3/2176 Class E amplifiers

Abstract

Exemplary embodiments are directed to differentially driving a load. An apparatus includes a differential drive amplifier including a switching device coupled with a first output node and a second output node. The first output node and the second output node drive a load network including primary coils. The differential drive amplifier also includes a drive circuit configured to drive the switching device. The drive circuit may be configured to provide a drive signal to the switching device to alter a conductive state of the switching device to produce a first output signal at the first output node and a second output signal at the second output node. The first and second output signals may be substantially equal in magnitude but opposite in polarity relative to a reference voltage.

Claims

1. An apparatus for reducing an amplifier output noise, comprising:

a switching device having a conductive state and configured to receive a drive signal, the switching device coupled to a first output node and a second output node, the conductive state altered based on the drive signal to produce a first output signal having a first current value at the first output node and a second output signal having a second current value at the second output node, the first and second current values substantially equal in magnitude; and

a first coil driven by the first output node; and

a second coil driven by the second output node, the first coil and the second coil configured to wirelessly output power at a level sufficient to power or charge a receiver device.

2. The apparatus of claim 1, wherein the switching device is configured to float between the first output and the second output node, the first output node coupled with ground through a first choke inductor and the second output node coupled with a supply voltage through a second choke inductor.

3. The apparatus of claim 2, wherein the first choke inductor and the second choke inductor are positioned to have a coupling effect.

4. The apparatus of claim 1, further comprising a drive circuit configured to generate the drive signal.

5. The apparatus of claim 4, wherein the drive circuit is an isolated drive circuit comprising a transformer.

6. The apparatus of claim 1, further comprising a capacitance network coupled between the first output node and the second output node, the capacitance network including one or more capacitors between the first output node and the second output node.

7. The apparatus of claim 1, further comprising a capacitance network, the capacitance network including one or more capacitors between the first output node and ground, and one or more capacitors between the second output node and the ground.

8. The apparatus of claim 1, wherein the first coil and the second coil are arranged such that currents through the first coil and the second coil generate respective magnetic fields having the same polarity.

9. The apparatus of claim 1, wherein one or more capacitors is included between the first coil and the second coil.

10. The apparatus of claim 1, further comprising a differential drive amplifier comprising the switching device, the first output node, and the second output node.

15. The apparatus of claim 1, wherein the first coil and the second coil are positioned to have a coupling effect.

22. The apparatus of claim 1, wherein the switching device comprises a single switching device.

25. The apparatus of claim 1, wherein the first coil and the second coil are connected at a central point to generate a single coil arrangement.

11. A method for reducing an amplifier output noise, comprising:

receiving a drive signal from a drive circuit at a switching device;

altering a conductive state of the switching device based on the drive signal to produce a first output signal having a first current value at a first output node and a second output signal having a second current value at a second output node, the first and second current values being substantially equal in magnitude; and

driving a first coil with the first output signal by the first output node and a second coil with the second output signal by the second output node; and

wirelessly outputting power by the first coil and the second coil at a level sufficient to power or charge a receiver device.

16. The method of claim 11, wherein the switching device is configured to float between the first output node and the second output node, the first output node coupled with ground through a first choke inductor and the second output node coupled with a supply voltage through a second choke inductor.

17. The method of claim 16, wherein the first choke inductor and the second choke inductor are positioned to have a coupling effect.

18. The method of claim 11, wherein the first coil and the second coil are positioned to have a coupling effect.

23. The method of claim 11, wherein the switching device comprises a single switching device.

26. The method of claim 11, wherein the first coil and the second coil are connected at a central point to generate a single coil arrangement.

27. The method of claim 11, further comprising generating the drive signal with the drive circuit.

28. The method of claim 27, wherein the drive circuit is an isolated drive circuit comprising a transformer.

29. The method of claim 11, wherein the switching device comprises a capacitance network coupled between the first output node and the second output node, the capacitance network including one or more capacitors between the first output node and the second output node.

30. The method of claim 11, wherein the switching device comprises a capacitance network, the capacitance network including one or more capacitors between the first output node and ground and one or more capacitors between the second output node and the ground.

31. The method of claim 11, wherein the first coil and the second coil are arranged such that currents through the first coil and the second coil generate respective magnetic fields having the same polarity.

32. The method of claim 11, wherein the switching device includes one or more capacitors between the first coil and the second coil.

33. The method of claim 11, wherein a differential drive amplifier comprises the switching device, the first output node, and the second output node.

12. An apparatus for reducing an amplifier output noise, comprising:

means for receiving a drive signal from a drive circuit at a switching device;

means for altering a conductive state of the switching device based on the drive signal to produce a first output signal having a first current value at a first output node and a second output signal having a second current value at a second output node, the first and second current values being substantially equal in magnitude; and

means for driving a first coil with the first output signal by the first output node and a second coil with the second output signal by the second output node, the first coil and the second coil configured to wirelessly output power at a level sufficient to power or charge a receiver device.

19. The apparatus of claim 12, wherein the switching device is configured to float between the first output node and the second output node, the first output node coupled with ground through a first choke inductor and the second output node coupled with a supply voltage through a second choke inductor.

20. The apparatus of claim 19, wherein the first choke inductor and the second choke inductor are positioned to have a coupling effect.

21. The apparatus of claim 12, wherein the first coil and the second coil are positioned to have a coupling effect.

24. The apparatus of claim 12, wherein the switching device comprises a single switching device.

34. The apparatus of claim 12, wherein the first coil and the second coil are connected at a central point to generate a single coil arrangement.

35. The apparatus of claim 12, further comprising means for generating the drive signal, the means for generating the drive signal comprising the drive circuit.

36. The apparatus of claim 35, wherein the drive circuit is an isolated drive circuit comprising a transformer.

37. The apparatus of claim 12, further comprising means for capacitively coupling the first output node and the second output node, the means for capacitively coupling including one or more capacitors between the first output node and the second output node.

38. The apparatus of claim 12, further comprising first means for capacitively coupling the first output node and ground and second means for capacitively coupling the second output node and the ground, the first means for capacitively coupling including one or more capacitors between the first output node and the ground, the second means for capacitively coupling including one or more capacitors between the second output node and the ground.

39. The apparatus of claim 12, wherein the first coil and the second coil are arranged such that currents through the first coil and the second coil generate respective magnetic fields having the same polarity.

40. The apparatus of claim 12, further comprising means for capacitively coupling the first coil and the second coil, the means for capacitively coupling including one or more capacitors between the first coil and the second coil.

41. The apparatus of claim 12, wherein a differential drive amplifier comprises the switching device, the first output node, and the second output node.

13. An apparatus for powering or charging a device, comprising:

a first coil driven by a first signal having a first current value; and

a second coil driven by a second signal having a second current value, the first and second current values being substantially equal in magnitude, the first coil and the second coil having a spiral configuration within a common plane that provides for co-location of substantially equal and opposite voltages within the first and second coils, respectively, at substantially any location on the common plane, the first coil and the second coil configured to wirelessly output power at a level sufficient to power or charge a receiver device.

14. The apparatus of claim 13, wherein the first coil is physically connected to the second coil at a central point to generate a single coil arrangement.

42. A method for powering or charging a device, comprising:

driving a first coil by a first signal having a first current value; and

driving a second coil by a second signal having a second current value, the first and second current values being substantially equal in magnitude, the first coil and the second coil having a spiral configuration within a common plane that provides for co-location of substantially equal and opposite voltages within the first and second coils, respectively, at substantially any location on the common plane, the first coil and the second coil configured to wirelessly output power at a level sufficient to power or charge a receiver device.

43. The method of claim 42, wherein the first coil is physically connected to the second coil at a central point to generate a single coil arrangement.

44. An apparatus for powering or charging a device, comprising:

means for driving a first coil by a first signal having a first current value; and

means for driving a second coil by a second signal having a second current value, the first and second currents being substantially equal in magnitude, the first coil and the second coil having a spiral configuration within a common plane that provides for co-location of substantially equal and opposite voltages within the first and second coils, respectively, at substantially any location on the common plane, the first coil and the second coil configured to wirelessly output power at a level sufficient to power or charge a receiver device.

45. The apparatus of claim 44, wherein the first coil is physically connected to the second coil at a central point to generate a single coil arrangement.