Composite amplifier

• US 20040263242A1
• Filed: 05/28/2004
• Published: 12/30/2004
• Est. Priority Date: 11/29/2001
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Hellberg, Richard
• Granted Patent: US 7,071,774 B2
• Time in Patent Office: Days
• US Class Current: 330/2
• CPC Class Codes: H03F 1/0294 using vector summing of two or more constant amplitude phase-modulated signals
• CPC Class Codes: H03F 1/3282 Acting on the phase and the amplitude of the input signal
• CPC Class Codes: H03F 1/3294 Acting on the real and imaginary components of the input signal

Abstract

A composite amplifier includes a first and a second power amplifier (16, 18) connected to a Chireix output network (20). Means (10, 22) provide equal first and linear drive signal components that depends linearly on the amplitude A(t) of an amplitude modulated input signal. Further means (10, 24)provide first and second nonlinear drive signal components that have the same magnitude but opposite signs and depend non-linearly as {square root}1-A(t) on the amplitude A(t) and are in quadrature to the first and second linear drive signal components. Means (26, 28, 30, 32) individually adjust amplitudes and phases of the drive signal components to lower drive power consumption. Means (34, 36) form a first composite drive signal to the first power amplifier by adding the adjusted first linear drive signal component to the adjusted first non-linear drive signal component a second composite drive signal to the second power amplifier by adding the adjusted second linear drive signal component to the adjusted second non-linear drive signal component.

Claims

1. A composite amplifier including a first and a second power amplifier connected to a Chireix type output network, said composite amplifier having a modulated input signal and substantially constant voltage amplitude at the output nodes of said power amplifiers, said composite amplifier including means generating, for at least one of said power amplifiers, a low power drive signal having non-constant amplitude that depends non-linearly on the amplitude of said input signal.

2. The amplifier of claim 1, including means for forming each low power drive signal as a combination of a linear drive signal component, which depends linearly on the amplitude of said input signal, and a non-linear drive signal component, which depends non-linearly on the amplitude of said input signal.

3. The amplifier of claim 2, including means for individually adjusting at least one of amplitude and phase of at least one of said linear and non-linear drive signal components to lower drive power consumption.

4. The amplifier of claim 3, including means generating low power drive signals for both power amplifiers.

5. The amplifier of claim 4, including

means for adjusting amplitude and phase of said linear drive signal components by determining, based on a model emulating the behavior of said output network, amplitude and phase of the current in each power amplifier output node when the output node voltages of both power amplifiers are equal;

and

means for adjusting amplitude and phase of said non-linear drive signal components by determining, based on said model emulating the behavior of said output network, amplitude and phase of the current in each power amplifier output node when the output node voltages of both power amplifiers are of equal magnitude but have opposite signs.

6. The amplifier of claim 4, including

means for adjusting amplitude and phase of said linear drive signal components for maximizing output power and efficiency at maximum input signal amplitude;

and

means for adjusting amplitude and phase of said non-linear drive signal components for minimizing average power consumption.

7. The amplifier of claim 3, including means for frequency dependent amplitude and phase adjustment of said non-linear drive signal component.

8. The amplifier of claim 3, including means for frequency dependent amplitude and phase adjustment of both said linear and non-linear drive signal components.

9. The amplifier of claim 3, wherein said non-linear drive signal component depends as {square root}{square root over (1−

A(t)²)} on the amplitude A(t) of said input signal.

10. The amplifier of claims 3, wherein said non-linear drive signal component depends as {square root}{square root over (1−

(k·

A(t))²)}−

A(t)·

{square root}{square root over (1−

k²)} on the amplitude A(t) of said input signal, where k is a constant slightly smaller than 1.

11. A transmitter including a composite amplifier having a first and a second power amplifier connected to a Chireix type output network, said composite amplifier having a modulated input signal and substantially constant voltage amplitude at the output nodes of said power amplifiers, said composite amplifier including means generating, for at least one of said power amplifiers, a low power drive signal having non-constant amplitude that depends non-linearly on the amplitude of said input signal.

12. The transmitter of claim 11, including means for forming each low power drive signal as a combination of a linear drive signal component, which depends linearly on the amplitude of said input signal, and a non-linear drive signal component, which depends non-linearly on the amplitude of said input signal.

13. The transmitter of claim 12, including means for individually adjusting at least one of amplitude and phase of at least one of said linear and non-linear drive signal components to lower drive power consumption.

14. The transmitter of claim 13, including means generating low power drive signals for both power amplifiers.

15. The transmitter of claim 14, including

means for adjusting amplitude and phase of said linear drive signal components by determining, based on a model emulating the behavior of said output network, amplitude and phase of the current in each power amplifier output node when the output node voltages of both power amplifiers are equal;

and

means for adjusting amplitude and phase of said non-linear drive signal components by determining, based on said model emulating the behavior of said output network, amplitude and phase of the current in each power amplifier output node when the output node voltages of both power amplifiers are of equal magnitude but have opposite signs.

16. The transmitter of claim 14, including

means for adjusting amplitude and phase of said linear drive signal components for maximizing output power and efficiency at maximum input signal amplitude;

and

means for adjusting amplitude and phase of said non-linear drive signal components for minimizing average power consumption.

17. The transmitter of claim 13, including means for frequency dependent amplitude and phase adjustment of said non-linear drive signal component.

18. The transmitter of claim 13, including means for frequency dependent amplitude and phase adjustment of both said linear and non-linear drive signal components.

19. The transmitter of claim 13, wherein said non-linear drive signal component depends as {square root}{square root over (1−

A(t)²)} on the amplitude A(t) of said input signal.

20. The transmitter of claims 13, wherein said non-linear drive signal component depends as {square root}{square root over (1−

(k·

A(t))²)}−

A(t)·

{square root}{square root over (1−

k²)} on the amplitude A(t) of said input signal, where k is a constant slightly smaller than 1.

21. A method of driving a composite amplifier including a first and a second power amplifier connected to a Chireix type output network, said composite amplifier having a modulated input signal and substantially constant voltage amplitude at the output nodes of said power amplifiers, said method including the step of generating, for at least one of said power amplifiers, a low power drive signal having non-constant amplitude that depends non-linearly on the amplitude of said input signal.

22. The method of claim 21, including the step of forming each low power drive signal as a combination of a linear drive signal component, which depends linearly on the amplitude of said input signal, and a non-linear drive signal component, which depends non-linearly on the amplitude of said input signal.

23. The method of claim 22, including the step of individually adjusting at least one of amplitude and phase of at least one of said linear and non-linear drive signal components to lower drive power consumption.

24. The method of claim 23, including the step of generating low power drive signals for both power amplifiers.

25. The method of claim 24, including the steps of

adjusting amplitude and phase of said linear drive signal components by determining, based on a model emulating the behavior of said output network, amplitude and phase of the current in each power amplifier output node when the output node voltages of both power amplifiers are equal;

and

adjusting amplitude and phase of said non-linear drive signal components by determining, based on said model emulating the behavior of said output network, amplitude and phase of the current in each power amplifier output node when the output node voltages of both power amplifiers are of equal magnitude but have opposite signs.

26. The method of claim 24, including the steps of

adjusting amplitude and phase of said linear drive signal components for maximizing output power and efficiency at maximum input signal amplitude;

and

adjusting amplitude and phase of said non-linear drive signal components for minimizing average power consumption.

27. The method of claim 23, including the step of frequency dependent amplitude and phase adjustment of said non-linear drive signal component.

28. The method of claim 23, including the step of frequency dependent amplitude and phase adjustment of both said linear and non-linear drive signal components.

29. The method of claim 23, wherein said non-linear drive signal component depends as {square root}{square root over (1−

A(t)²)} on the amplitude A(t) of said input signal.

30. The method of claim 23, wherein said non-linear drive signal component depends as {square root}{square root over (1−

(k·

A(t))²)}−

A(t)·

{square root}{square root over (1−

k²)} on the amplitude A(t) of said input signal, where k is a constant slightly smaller than 1.