APPARATUS AND METHOD FOR IMPLEMENTING A DIFFERENTIAL DRIVE AMPLIFIER AND A COIL ARRANGEMENT

• US 20110133570A1
• Filed: 12/02/2010
• Published: 06/09/2011
• Est. Priority Date: 12/07/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Tseng, Ryan, Mayo, Gabriel I.
• Granted Patent: US 8,772,975 B2
• Time in Patent Office: Days
• 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, comprising:

a switching device responsive to a drive signal and coupled with a first output node and a second output node; and

a first primary coil driven via the first output node and a second primary coil driven via the second output node, the drive signal to the switching device alters 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 being substantially equal in magnitude but opposite in polarity relative to a reference voltage.

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 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, 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 ground.

8. The apparatus of claim 1, wherein the first primary coil and the second primary coil are arranged such that currents through the first primary coil and the second primary 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 primary coil and the second primary coil.

10. A wireless power transmitter, comprising:

a differential drive amplifier having a first output node and a second output node; and

a first primary coil driven via the first output node and a second primary coil driven via the second output node;

wherein the differential drive amplifier comprises;

a switching device responsive to a drive signal and coupled with the first output node and coupled with the second output node, the drive signal to the switching device alters 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 being substantially equal in magnitude but opposite in polarity relative to a reference voltage.

11. The wireless power transmitter of claim 10, further comprising a supply network configured to provide power to the different drive amplifier.

12. The wireless power transmitter of claim 11, wherein the supply network includes a first choke inductor coupled between the first output node and ground, and a second choke inductor coupled between the second output node and a supply voltage, and

wherein the switching device of the differential drive amplifier is configured to float between the first output and the second output node.

13. The wireless power transmitter of claim 11, wherein the supply network includes a first choke inductor coupled between the first output node and ground, and a second choke inductor coupled between the second output node and a supply voltage, the first choke inductor and the second choke inductor being positioned to generate a coupling effect, and

wherein the switching device of the differential drive amplifier is configured to float between the first output and the second output node.

14. The wireless power transmitter of claim 10, further comprising a drive circuit configured to provide a drive signal to the switching device.

15. The wireless power transmitter of claim 14, wherein the drive circuit of the differential drive amplifier is an isolated drive circuit comprising a transformer.

16. The wireless power transmitter of claim 10, wherein the differential drive amplifier further 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.

17. The wireless power transmitter of claim 10, wherein the differential drive amplifier further 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 ground.

18. The wireless power transmitter of claim 10, wherein the first primary coil and the second primary coil are arranged such that currents through the first primary coil and the second primary coil generate respective magnetic fields having the same polarity.

19. The wireless power transmitter of claim 10, wherein one or more capacitors is included between the first primary coil and the second primary coil.

20. A wireless power system, comprising:

a wireless power receiver comprising at least one secondary coil; and

a wireless power transmitter, the wireless power transmitter comprising;

a differential drive amplifier having a first output node and a second output node; and

a first primary coil driven via the first output node and a second primary coil driven via the second output node;

wherein the differential drive amplifier comprises;

a switching device responsive to a drive signal and coupled with the first output node and the second output node; and

wherein the drive signal to the switching device alters 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 being substantially equal in magnitude but opposite in polarity relative to a reference voltage.

21. A method, 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 at a first output node and a second output signal at a second output node, the first and second output signals being substantially equal in magnitude but opposite in polarity relative to a reference voltage; and

driving a load network with the first output signal and the second output signal via the first output node and the second output node, respectively.

22. An apparatus, 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 at a first output node and a second output signal at a second output node, the first and second output signals being substantially equal in magnitude but opposite in polarity relative to a reference voltage; and

means for driving a load network with the first output signal and the second output signal via the first output node and the second output node, respectively.

23. An apparatus, comprising:

a first coil driven by a first signal; and

a second coil driven by a second signal, the first and second signals being substantially equal in magnitude but opposite in polarity relative to a reference voltage;

wherein the first coil and the second coil have 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 any location on the common plane.

24. The apparatus of claim 23, wherein the first coil is physically connected to the second coil at a central point to generate a single coil arrangement.