Linearizer for a power amplifier

• US 20020125947A1
• Filed: 03/11/2002
• Published: 09/12/2002
• Est. Priority Date: 03/09/2001
• Status: Active Grant

• Current Assignee: COMS IP Holdings LLC
• Original Assignee: DragonWave Incorporated
• Inventors: Ren, Qiming
• Granted Patent: US 6,538,509 B2
• Time in Patent Office: Days
• US Class Current: 330/149
• CPC Class Codes: H03F 1/3252 using multiple parallel paths between input and output H03F1/3258, H03F1/3282, H03F1/3294 take precedence
• CPC Class Codes: H03F 1/3276 using the nonlinearity inherent to components, e.g. a diode
• CPC Class Codes: H03F 1/3282 Acting on the phase and the amplitude of the input signal

Abstract

A predistortion linearizer for a microwave power amplifier comprises a signal separator for receiving a signal and dividing the signal into first and second signals, a first path for carrying the first signal and a second path for carrying the second signal, and a signal combiner for combining the signals from the first and second paths. The second path between the separator and combiner includes a non-linear device for receiving the second signal and generating distortion therefrom, and a vector modulator for controlling at least one of the amplitude and phase of the second signal.

Claims

1. A predistortion linearizer comprising;

a signal separator for receiving a signal and for dividing the signal into a first signal and a second signal,

a first path for carrying said first signal,

a second path for carrying said second signal,

a signal combiner for combining the signals from the first and second paths, and

wherein said second path between said separator and combiner includes a non-linear device for receiving said second signal and generating distortion therefrom, and vector modulator means for controlling at least one of the amplitude and phase of the second signal.

2. A predistortion linearizer as claimed in claim 1, wherein said signal separator comprises a wideband signal separator.

3. A predistortion linearizer as claimed in claim 2, wherein said signal separator has a bandwidth of at least 20% of the center frequency of the input signal.

4. A predistortion linearizer as claimed in claim 1, wherein said signal combiner comprises a wideband coupler.

5. A predistortion linearizer as claimed in claim 4, wherein said wideband coupler has a bandwidth of at least 20% of the centre frequency of said input signal.

6. A predistortion linearizer as claimed in claim 1, wherein said first path includes a delay line for changing the phase of the first signal relative to the second signal.

7. A predistortion linearizer as claimed in claim 1, wherein said first path includes amplifier means for amplifying said first signal.

8. A predistortion linearizer as claimed in claim 7, further comprising means for controlling the amplitude of said first signal.

9. A predistortion linearizer as claimed in claim 8, wherein said amplitude controlling means includes a variable gain amplifier.

10. A predistortion linearizer as claimed in claim 8, wherein said amplitude controlling means comprises a variable attenuator.

11. A predistortion linearizer as claimed in claim 1, wherein said vector modulator means comprises a second signal separator for dividing said second signal into a first modulator signal and a second modulator signal, a third path for carrying said first modulator signal, a fourth path for carrying said second modulator signal and a signal combiner for combining the first and second modulator signals received from said third and fourth paths, and wherein said third path includes means for changing the phase of the first modulator signal and means for controlling the amplitude of said first modulator signal, and said fourth path includes means for controlling the amplitude of the second modulator signal.

12. A predistortion linearizer as claimed in claim 11, wherein said phase changing means comprises a delay line.

13. A predistortion linearizer as claimed in claim 11, wherein said second signal separator comprises a wideband separator.

14. A predistortion linearizer as claimed in claim 13, wherein said wideband signal separator has a bandwidth of at least 20% of the center frequency of the input signal.

15. A predistortion linearizer as claimed in claim 11, wherein said second signal combiner comprises a wideband signal combiner.

16. A predistortion linearizer as claimed in claim 15, wherein said wide band signal combiner has a bandwidth of at least 20% of the center frequency of said input signal.

17. A predistortion linearizer as claimed in claim 11, wherein said control means for controlling the amplitude of said first modulator signal comprises a variable attenuator.

18. A predistortion linearizer as claimed in claim 17, wherein said variable attenuator comprises a voltage controlled attenuator.

19. A predistortion linearizer as claimed in claim 11, wherein said means for varying the amplitude of said second modulator signal comprises a variable attenuator.

20. A predistortion linearizer as claimed in claim 19, wherein said variable attenuator comprises a voltage controlled attenuator.

21. A predistortion linearizer for a microwave power amplifier comprising:

a signal separator for receiving a signal and for dividing the signal into a first signal and a second signal,

a first path for carrying said first signal, said first path comprising an amplifier and means for attenuating the input power of said first signal to said amplifier,

a second path for carrying said second signal, said second path comprising a non-linear device for receiving said second signal and generating distortion therefrom and means for attenuating the power of the distorted signal from said non-linear device,

a signal combiner for combining the signals from said amplifier and said non-linear device into a signal for feeding into a power amplifier, wherein one of said first and second paths is longer than the other to add a phase difference between the signals in the first and second paths.

22. A predistortion linearizer as claimed in claim 21, wherein the additional length in one of said first and second paths is provided by a delay line.

23. A predistortion linearizer as claimed in claim 22, wherein said delay line comprises a variable length delay line.

24. A predistortion linearizer as claimed in claim 21, wherein said signal separator has a bandwidth of at least 20% of the center frequency of the input signal.

25. A predistortion linearizer as claimed in claim 22, wherein said signal combiner comprises a coupler having a bandwidth of at least 20% of the center frequency of the input signal.

27. A vector modulator as claimed in claim 26, wherein the means for changing the phase of the first modulator signal comprises a delay line.

28. A vector modulator as claimed in claim 26, wherein said signal separator comprises a wideband signal separator.

29. A vector modulator as claimed in claim 28, wherein the signal separator has a bandwidth of at least 20% of the center frequency of the input signal.

30. A vector modulator as claimed in claim 26, wherein the signal combiner comprises a wideband signal combiner.

31. A vector modulator as claimed in claim 29, wherein the signal combiner has a bandwidth of at least 20% of the center frequency of the input signal.

26. A vector modulator comprising a signal separator for dividing a signal into a first modulator signal and a second modulator signal, a first path for carrying said first modulator signal, a second path for carrying said second modulator signal and a signal combiner for combining the first and second modulator signals received from said first and second paths, wherein the first path includes means for changing the phase of the first modulator signal and means for controlling the amplitude of the first modulator signal, and the second path includes means for controlling the amplitude of the second modulator signal.