High-efficiency modulating RF amplifier

• US 6,816,016 B2
• Filed: 10/16/2003
• Issued: 11/09/2004
• Est. Priority Date: 08/10/2000
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Tropian, Inc. (Panasonic Holdings Corporation)
• Inventors: McCune, Earl, Sander, Wendell B., Meck, Ronald A.
• Primary Examiner(s): Mottola, Steven J.
• Application Number:
  US10/688,444
• Publication Number:
  US 20040080364A1
• Time in Patent Office: 390 Days
• Field of Search: 330/10, 330/124.R, 330/134, 330/207.A, 330/251, 330/285, 330/295, 330/51
• US Class Current: 330/295
• CPC Class Codes: H03F 1/0227 using supply converters

Abstract

The present invention, generally speaking, provides for high-efficiency power control of a high-efficiency (e.g., bard-limiting or switch-mode) power amplifier in such a manner as to achieve a desired control or modulation. Unlike the prior art, feedback is not required. That is, the amplifier may be controlled without continuous or frequent feedback adjustment. In one embodiment, the spread between a maximum frequency of the desired modulation and the operating frequency of a switch-mode DC-DC converter is reduced by following the switch-mode converter with an active linear regulator. The linear regulator is designed so as to control the operating voltage of the power amplifier with sufficient bandwidth to faithfully reproduce the desired amplitude modulation waveform. The linear regulator is further designed to reject variations on its input voltage even while the output voltage is changed in response to an applied control signal. This rejection will occur even though the variations on the input voltage are of commensurate or even lower frequency than that of the controlled output variation. Amplitude modulation may be achieved by directly or effectively varying the operating voltage on the power amplifier while simultaneously achieving high efficiency in the conversion of primary DC power to the amplitude modulated output signal. High efficiency is enhanced by allowing the switch-mode DC-to-DC converter to also vary its output voltage such that the voltage drop across the linear regulator is kept at a low and relatively constant level. Time-division multiple access (TDMA) bursting capability may be combined with efficient amplitude modulation, with control of these functions being combined. In addition, the variation of average output power level in accordance with commands from a communications system may also be combined within the same structure.

Claims

1. An RF amplifier apparatus, comprising:

a plurality of amplifiers modules, each amplifier module comprising a nonlinear switch-mode RF amplifier having an RF input configured to receive common RE input signal, and a power controller having a magnitude control input;

a magnitude driver, responsive to a magnitude input signal, operable to provide magnitude control signals to said magnitude control inputs of said plurality of power controllers; and

a summer configured to receive RF output signals from said plurality of amplifiers modules and provide a resultant RF output signals,

wherein said RF input signal drive one or more of said nonlinear switch-mode RF amplifiers between a hard-on state and a hard-off state, without operating said nonlinear switch-mode RF amplifiers in linear operating regions for any appreciable any percentage of time.

2. The RF amplifier apparatus of claim 1 wherein the RF input signal is a phase modulated RF input signal.

3. The RF amplifier apparatus of claim 1 wherein each power controller has a power supply input port configured to receive a DC supply voltage and a power control output configured to provide a variable supply output voltage to a supply input of its associated nonlinear switch-mode RF amplifier.

4. The RF amplifier apparatus of claim 3 wherein each power controller comprises a switch-mode converter configure to receive the DC supply voltage and provide the variable supply output voltage, said variable supply output voltage approximating a desired operating voltage level of said each power controller'"'"'s associated nonlinear switch-mode RF amplifier.

5. The RF amplifier apparatus of claim 4 wherein each power controller further comprises a regulator coupled between the supply input of its associated nonlinear switch-mode RF amplifier and an output of the switch-mode vower converter.

6. The RF amplifier apparatus of claim 5 wherein each switch-mode converter comprises a switch-mode power supply.

7. The RF amplifier apparatus of claim 1 wherein said magnitude control signals derive from a common magnitude control signal generated by said magnitude driver.

8. The RF amplifier apparatus of claim 1 wherein said magnitude control signals are individual and separate magnitude control signals generated for each associated power contoller.

9. The RF amplifier apparatus of claim 1 wherein each nonlinear switch-mode RF amplifier comprises a Class D amplifier.

10. The RF amplifier apparatus of claim 1 wherein each nonlinear switch-mode RF amplifier comprises a Class E amplifier.

11. The RF amplifier apparatus of claim 1 wherein each nonlinear switch-mode RF amplifier comprises a Class F amplifier.

12. A method of amplifying an RF signal, comprising:

applying an RF input signal to RF inputs of a plurality of nonlinear switch-mode RF amplifiers, said RF input signal operable to drive one or more of said nonlinear switch-mode RF amplifiers repeatedly between a hard-on state and a hard-off state, without operating said one or more nonlinear switch-mode RF amplifiers in linear operating region for any appreciable percentage of time;

applying magnitude control signals to magnitude control inputs of a plurality of power controllers associated with said plurality of nonlinear switch-mode RF amplifiers;

amplifying said RF input by said plurality of nonlinear switch-mode RF amplifiers, in accordance with associated magnitude control signals; and

summing RF output signals from the plurality of nonlinear switch-mode RF amplifiers to form a resultant RF output signal.

13. The method of claim 12 Wherein th RF input signal is a phase modulated signal.

14. The method of claim 12, further comprising:

applying a DC supply voltage to power supply input ports of each of aid plurality of power controllers;

generating a plurality of variable supply output voltages and;

applying said variable supply output voltages to supply inputs of said plurality of nonlinear switch-mode RF amplifiers.

15. The method of claim 14 wherein generating a plurality of variable supply output voltages comprises convert said DC supply voltage to asaid variable supply output voltages, said plurality of DC variable supply output voltages approximating desired operating voltage levels of said plurality of nonlinear switch-mode RF amplifiers.

16. The method of claim 15 wherein generating a plurality of variable supply output voltages further comprises regulating said DC variable supply output voltages.

17. The method of claim 15 wherein converting said DC supply voltage to a plurality of variable supply output voltages is performed by an associated plurality of switch-mode converters.

18. The method of claim 12 wherein each switch-mode power amplifier comprises a Class D amplifier.

19. The method of claim 12 wherein each switch-mode power amplifier comprises a Class E amplifier.

20. An RF amplifier apparatus, comprising:

a plurality of RF amplifier modules, each RF amplifier module having a power control circuit and a nonlinear RF amplifier, and each RF amplifier module configured to receive an RF input signal; and

a summer configured to receive RF output signals from said plurality of amplifier modules,

wherein said RF input signal drives one or more of said nonlinear RF amplifiers repeatedly between a hard-on state and a hard-off state, without operating said nonlinear RF amplifiers in linear operating regions for any appreciable percentage of time.

21. The RF amplifier apparatus of claim 20 wherein th nonlinear RF amplifiers comprise switch-mode amplifiers.

22. The RF amplifier apparatus of claim 20 wherein th power control circuits each include a switch-mode converter configured to receive DC supply voltage and provide a converted supply voltage.

23. The RF amplifier apparatus of claim 22 wherein the switch-mode converters provide ramp and level control.

24. The RF amplifier apparatus of claim 20 wherein th power control circuits each include a regulator configured to provide ramp and level control.

25. The RF amplifier apparatus of claim 21 wherein ea of the power control circuits further includes a regulator coupled between an output of the switch-mode converter and power control input of an associated nonlinear RF amplifier.