High power RF field effect transistor switching using DC biases

• US 9,368,975 B2
• Filed: 03/15/2013
• Issued: 06/14/2016
• Est. Priority Date: 11/30/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wheeland, Cody B., Irish, Linda S., Von Novak, William H. III, Mayo, Gabriel Isaac
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): Yeshaw, Esayas
• Application Number:
  US13/835,285
• Publication Number:
  US 20140152115A1
• Time in Patent Office: 1,187 Days
• Field of Search: 307/104
• US Class Current: 1/1
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/50 using additional energy repeaters between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H03J 3/20 of single resonant circuit by varying inductance only or capacitance only

Abstract

Systems, methods, and apparatus are provided for tuning in wireless power transfer circuits. One aspect of the disclosure provides an apparatus for tuning. The apparatus includes a field effect transistor having a gate, source, and drain, where the field effect transistor is configured to electrically engage a tuning element to an AC power path. In some embodiments, one of the source or drain contacts is at an alternating current voltage.

Claims

1. An apparatus for providing tuning in a wireless power transfer system, comprising:

a tuning element;

a field effect transistor having a gate, a first terminal contact, and a second terminal contact, said first terminal contact is at an alternating current (AC) voltage, the field effect transistor configured to electrically engage the tuning element to an AC power path based on a change in an electrical characteristic of the gate with respect to an electrical characteristic of the first terminal contact; and

a first capacitor coupled to the first terminal contact and a second capacitor coupled to the second terminal contact.

2. The apparatus of claim 1, further comprising a gate biasing circuitry configured to change the electrical characteristic of the gate with respect to the electrical characteristic of the first terminal contact to drive the field effect transistor, wherein the electrical characteristic comprises a bias potential.

3. The apparatus of claim 1, further comprising a bias circuitry configured to reduce output capacitance of the field effect transistor by biasing the second terminal contact such that the second terminal contact is at higher bias than the first terminal contact.

4. The apparatus of claim 3, wherein the drain bias circuitry comprises a self-biasing multiplier circuit.

5. The apparatus of claim 1, wherein the tuning element is connected parallel to the field effect transistor.

6. The apparatus of claim 1, wherein the field effect transistor comprises a n-type mosfet such that first terminal is a source terminal and the second terminal is a drain terminal of the field effect transistor.

7. The apparatus of claim 1, wherein the field effect transistor comprises a p-type mosfet such that first terminal is a drain terminal and the second terminal is a source terminal of the field effect transistor.

8. The apparatus of claim 1, wherein the tuning element comprises a capacitor or an inductor.

9. The apparatus of claim 1, further comprising a second tuning element, wherein the second tuning element comprises a capacitor or an inductor.

10. The apparatus of claim 1, wherein the first and the second capacitors are DC blocking capacitors and are configured to keep the first and the second terminal contacts floating relative to the AC path.

11. The apparatus of claim 1, wherein an output capacitance of the field effect transistor substantially approaches a desired tuning in the wireless power transfer system.

12. The apparatus of claim 1, wherein the gate is coupled to the first terminal with a capacitor.

13. A method of wireless transmitting power, the method comprising:

providing a tuning element;

providing a field effect transistor having a gate, a first terminal contact, a second terminal contact, said first terminal contact being at an alternating current (AC) voltage, and a first capacitor coupled to the first terminal contact and a second capacitor coupled to the second terminal contact; and

electrically engaging the tuning element to an AC power path based on changing an electrical characteristic of the gate with respect to an electrical characteristic of the first terminal contact of the field effect transistor.

14. The method of claim 13, further comprising the step of changing the electrical characteristic of the gate with respect to the electrical characteristic of the first terminal contact using a gate biasing circuitry for driving the field effect transistor, wherein the electrical characteristic comprises a bias potential.

15. The method of claim 13, further comprising the step of biasing the second terminal contact using a drain bias circuitry such that the second terminal contact is at higher bias than the first terminal contact.

16. The method of claim 15, wherein the drain bias circuitry comprises a self-biasing multiplier circuit.

17. The method of claim 13, wherein the tuning element is connected parallel to the field effect transistor.

18. The method of claim 13, wherein the field effect transistor comprises a n-type mosfet such that the first terminal is a drain terminal and the second terminal is a source terminal of the field effect transistor.

19. The method of claim 13, wherein the field effect transistor comprises a p-type mosfet such that the first terminal is a source terminal and the second terminal is a drain terminal of the field effect transistor.

20. The method of claim 13, wherein the tuning element comprises a capacitor or an inductor.

21. The method of claim 13, further comprising the step of providing a second tuning element wherein the second tuning element comprises a capacitor or an inductor.

22. The method of claim 13, further comprising the step of keeping the first terminal contact and the second terminal contact floating relative to the AC path.

23. The method of claim 13, wherein an output capacitance of the field effect transistor substantially approaches a desired tuning in the wireless power transfer system.

24. The method of claim 13, wherein the gate is coupled to the first terminal with a capacitor.

25. A tuning circuit, configured to provide tuning in a wireless power transfer system, the tuning circuit comprising:

means for tuning;

means for switching, said means for switching comprising a field effect transistor having a gate, a first terminal contact, and a second terminal contact, said first terminal contact being at an alternating current (AC) voltage;

means for electrically engaging the tuning element to an AC power path based on changing an electrical characteristic of the gate with respect to an electrical characteristic of the first terminal contact of the field effect transistor;

first means for providing capacitance to the means for switching at a first terminal contact of the means for switching; and

second means for providing capacitance to the means for switching at a second terminal contact of the means for switching.

26. The tuning circuit of claim 25, further comprising the means for electrically engaging using a gate biasing circuitry for driving the field effect transistor, wherein the electrical characteristic comprises a bias potential.

27. The tuning circuit of claim 25, further comprising means for biasing the second terminal contact using a drain bias circuitry such that the second terminal contact is at higher bias than the first terminal contact.

28. The tuning circuit of claim 27, wherein the drain bias circuitry comprises a self-biasing multiplier circuit.

29. The tuning circuit of claim 25, wherein the means for tuning is connected parallel to the field effect transistor.

30. The tuning circuit of claim 25, wherein the field effect transistor comprises a n-type mosfet such that the first terminal is a drain terminal and the second terminal is a source terminal of the field effect transistor.

31. The tuning circuit of claim 25, wherein the field effect transistor comprises a p-type mosfet such that the first terminal is a source terminal and the second terminal is a drain terminal of the field effect transistor.

32. The tuning circuit of claim 25, wherein the means for tuning element comprises a capacitor or an inductor.

33. The tuning circuit of claim 25, further comprising means for providing a second means for tuning, wherein the second means for tuning comprises a capacitor or an inductor.

34. The tuning circuit of claim 25, further comprising means for keeping the first terminal and the second terminal floating relative to the AC path.

35. The tuning circuit of claim 25, wherein an output capacitance of the field effect transistor substantially approaches a desired tuning in the wireless power transfer system.

36. The tuning circuit of claim 25, wherein the gate is coupled to the first terminal with a capacitor.