Radio frequency power amplifier and method using a controlled supply

• US 20070249304A1
• Filed: 06/15/2007
• Published: 10/25/2007
• Est. Priority Date: 03/25/2005
• Status: Active Grant

• Current Assignee: PWRF, Inc.
• Original Assignee: PulseWave RF, Inc.
• Inventors: Mekechuk, Kelly, Snelgrove, William
• Granted Patent: US 7,474,149 B2
• Time in Patent Office: Days
• US Class Current: 455/127.200
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• CPC Class Codes: H03F 1/0227 using supply converters
• CPC Class Codes: H03F 2200/102 A non-specified detector of a signal envelope being used in an amplifying circuit
• CPC Class Codes: H03F 2200/331 Sigma delta modulation being used in an amplifying circuit
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2200/504 the supply voltage or current being continuously controlled by a controlling signal, e.g. the controlling signal of a transistor implemented as variable resistor in a supply path for, an IC-block showed amplifier
• CPC Class Codes: H03F 3/191 Tuned amplifiers H03F3/193, H03F3/195 take precedence
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H03G 3/004 Control by varying the supply voltage

Abstract

A radio frequency power amplifier includes a feedback control system coupled to an input signal and a first feedback signal and configured to provide an output; a controlled supply configured to provide power that is controlled in accordance with a signal; and a radio frequency gain stage powered from the controlled supply, driven by the output from the feedback control system, and configured to provide an output signal at the radio frequency to a resonant load, where the first feedback signal corresponds to the output signal. Some embodiments include a sequencer in the feedback control system and others utilize an additional feedback loop to control the power provided by the controlled supply.

Claims

1. A radio frequency power amplifier comprising:

a feedback control system coupled to an input signal and a first feedback signal and configured to provide a sequencer output, the sequencer output comprising waveforms occurring at an average frequency in accordance with a radio frequency with timing determined by the feedback control system;

a controlled supply configured to provide power that is controlled in accordance with the input signal; and

a radio frequency gain stage powered from the controlled supply, driven by the sequencer output, and configured to provide an output signal at the radio frequency, the first feedback signal corresponding to the output signal.

2. The radio frequency amplifier of claim 1 wherein the controlled supply is further configured to provide the power at a level in accordance with an envelope of the input signal.

3. The radio frequency amplifier of claim 1 wherein the controlled supply is further configured to provide the power at one of a plurality of discrete levels, with the one of the plurality of discrete levels selected in accordance with the input signal.

4. The radio frequency amplifier of claim 1 wherein the controlled supply is further configured to provide the power in accordance with an error signal that is based on the input signal and the first feedback signal.

5. The radio frequency amplifier of claim 1 wherein the controlled supply is further configured to provide the power at a level in accordance with an envelope of the input signal and in accordance with an envelope of an error signal that is based on the input signal and the first feedback signal.

6. The radio frequency amplifier of claim 1 wherein the controlled supply is further configured to provide the power in accordance with one or more of:

an error signal that is based on the input signal and the first feedback signal;

the error signal as processed by the feedback control system; and

state changes in one of the error signal as processed and the sequencer output.

7. The radio frequency amplifier of claim 1 wherein the controlled supply is further configured to provide power having a plurality of signals and wherein the radio frequency gain stage comprises a plurality of radio frequency gain stages, each coupled to one of the plurality of signals.

8. The radio frequency amplifier of claim 7 wherein one of the plurality of signals is used to control a bias level for at least one of the plurality of radio frequency gain stages.

9. The radio frequency amplifier of claim 1 wherein the controlled supply is further configured to provide a plurality of signals with at least one of the plurality of signals coupled to the feedback system and used to control a phase associated with an error signal as processed by the feedback control system.

10. The radio frequency amplifier of claim 1 wherein the controlled supply is further configured to provide a plurality of signals with at least one of the plurality of signals coupled to the feedback system and used to control a characteristic of the sequencer output.

11. The radio frequency amplifier of claim 1 further comprising a second feedback system responsive to the sequencer output and configured to provide a second feedback signal that is coupled to the feedback control system;

and wherein the controlled supply is further configured to provide a plurality of signals with at least one of the plurality of signals coupled to the second feedback system and used to control a characteristic of the second feedback signal.

12. The radio frequency amplifier of claim 1 further comprising:

an amplitude control means coupled to the output signal and configured to limit an amplitude of the output signal; and

wherein the controlled supply is further configured to provide a plurality of signals with at least one of the plurality of signals coupled to the amplitude control means and used to control a level at which the amplitude control means is configured to limit the amplitude of the output signal.

13. The radio frequency amplifier of claim 1 wherein the controlled supply further comprises:

a controller for processing a controller input signal and providing a controller output signal; and

a controlled power source responsive to the controller and configured to provide the power.

14. The radio frequency amplifier of claim 13 wherein the controlled power source includes a linear regulator.

15. The radio frequency amplifier of claim 13 wherein the controlled power source includes a switching regulator that is synchronously clocked in accordance with a clock.

16. The radio frequency amplifier of claim 13 wherein the controlled power source includes a switching regulator that is asynchronously clocked.

17. The radio frequency amplifier of claim 13 wherein the controller further comprises a signal conditioner coupled to the controller.

18. The radio frequency amplifier of claim 13 wherein the controller further comprises a signal conditioner configured to provide the controller input signal, the controller input signal including an envelope signal having an amplitude limited by the signal conditioner.

19. The radio frequency amplifier of claim 13 wherein the controller further comprises a signal conditioner configured to provide the controller input signal, the controller input signal including an envelope signal having an offset added by the signal conditioner.

20. A radio frequency power amplifier comprising:

a feedback control system coupled to an input signal and a first feedback signal and configured to provide a control signal;

a controlled supply configured to provide power, the power controlled in accordance with an error signal based on a combination of the input signal and the first feedback signal; and

a radio frequency gain stage using the power from the controlled supply, driven by the control signal, and configured to provide an output signal, the first feedback signal corresponding to the output signal.

21. The radio frequency power amplifier of claim 20 further comprising a detector configured to provide the error signal, the error signal indicative of a difference between the power and desired power.

22. The radio frequency power amplifier of claim 20 further comprising a detector configured to provide the error signal, the error signal corresponding to a harmonic level, the harmonic level indicative of present level of the power relative to a desired level of the power.

23. The radio frequency power amplifier of claim 20 further comprising a filter, wherein the power is coupled to the radio frequency gain stage through the filter, the filter rejecting undesired energy that is associated with the power.

24. The radio frequency power amplifier of claim 20 further comprising an envelope detector configured to provide an envelope signal corresponding to an envelope of the input signal, the envelope signal coupled to the controlled supply and used to establish an initial power level.

25. The radio frequency power amplifier of claim 20 further comprising an envelope detector configured to provide an envelope signal corresponding to an envelope of the input signal, the envelope signal coupled to the controlled supply and used to bias a power level in a direction of change of the envelope signal.

26. The radio frequency power amplifier of claim 20, wherein the feedback control system is configured to provide the error signal, the error signal corresponding to a difference between the input signal and the feedback signal.

27. The radio frequency power amplifier of claim 26, wherein the feedback control system is configured to provide the error signal, the error signal corresponding to a difference between the input signal and the feedback signal as filtered by a loop filter.

28. The radio frequency power amplifier of claim 20, wherein the controlled supply is further configured to provide power having a plurality of signals and wherein the radio frequency gain stage comprises a plurality of radio frequency gain stages, each coupled to one of the plurality of signals.

29. The radio frequency amplifier of claim 28 wherein one of the plurality of signals is used to control a bias level for at least one of the plurality of radio frequency gain stages.

30. The radio frequency power amplifier of claim 20, wherein the feedback control system further comprises a sequencer and the control signal is a sequencer output, the sequencer output having an average frequency that is equivalent to a carrier frequency of the output signal and suitable for driving the radio frequency gain stage to replicate amplitude and phase modulation corresponding to the input signal.

31. The radio frequency power amplifier of claim 30 wherein the feedback control system is configured to provide the error signal, the error signal corresponding to a difference between the input signal and the feedback signal.

32. The radio frequency amplifier of claim 30 wherein the controlled supply is further configured to provide the power in accordance with one or more of:

the error signal as processed by the feedback control system; and

state changes in one of the error signal as processed and the sequencer output.

33. The radio frequency amplifier of claim 30, wherein the feedback control system is configured to provide the error signal, the error signal corresponding to one or more of pulse lengths and occurrence rates at the sequencer output.

34. The radio frequency power amplifier of claim 30, wherein the feedback control system is configured to provide the error signal, the error signal corresponding to a phase change between an input to the sequencer and a preceding sequencer output.

35. A radio frequency power amplifier comprising:

a loop filter with an input coupled to a signal corresponding to an input signal and a feedback signal;

a sequencer responsive to a filter output from the loop filter and configured to provide a sequencer output, where the sequencer output has an OFF state with a starting time that corresponds to the filter output, the OFF state having a predetermined duration;

a radio frequency stage driven by the sequencer output and configured to provide an output signal, the feedback signal corresponding to the output signal; and

a controlled supply configured to provide power to the radio frequency stage, wherein the power is controlled in accordance with amplitude variations of the input signal.