Parallel amplifier architecture using digital phase control techniques

• US 6,799,020 B1
• Filed: 07/20/1999
• Issued: 09/28/2004
• Est. Priority Date: 07/20/1999
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Heidmann, Peter D., Burke, Joseph P.
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): SOBUTKA, PHILIP
• Application Number:
  US09/357,695
• Time in Patent Office: 1,897 Days
• Field of Search: 455/103, 455/104, 455/105, 455/115, 455/126, 455/91, 455/313, 330/107, 330/124.R, 330/295, 375/295, 375/297, 331/1.A, 342/372
• US Class Current: 455/103
• CPC Class Codes: H03F 1/0294 using vector summing of two or more constant amplitude phase-modulated signals
• CPC Class Codes: H03F 2203/21163 An output signal dependant signal being measured by power measuring, e.g. by an inductive coupler, at the output of a power amplifier
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence
• CPC Class Codes: H03F 3/602 Combinations of several amplifiers

Abstract

An improved method and apparatus for using parallel amplifiers to efficiently amplify an information signal are disclosed. The improved apparatus utilizes digital signal manipulation techniques in optimizing the phase of the upconverted input signals provided to each of the parallel amplifiers. The phase and amplitude of the input signals are adjusted such that the power measured at the output of a combiner is maximized as compared to the sum of the power of combiner input signals.

Claims

1. Parallel amplifier transmitter comprising:

a) first signal transmission subsystem comprising a phase-controlled digital oscillator for generating a first phase-controlled digital mixing signal having a phase based on a first phase control signal, wherein the first signal transmission subsystem uses the first phase-controlled digital mixing signal to produce a first phase-controlled amplified signal having a first phase based on the first phase control signal;

b) at least one additional signal transmission subsystem, each producing an additional phase-controlled amplified signal;

c) combiner means for combining said phase-controlled amplified signals to produce a combined amplified signal;

d) combiner power measurement means, operably connected to said combiner means, for measuring the power of said combined amplified signal and producing a combiner power measurement; and

e) control module, operably connected to said combiner power measurement means and to each of said signal transmission subsystems, for receiving said combiner power measurement from said combiner power measurement means and for receiving a subsystem power measurement based on each of said phase-controlled amplified signals produced by each of said signal transmission subsystems, and for adjusting said first digital phase control signal based on the values of said combiner power measurement and said subsystem power measurements.

2. Apparatus for upconverting and amplifying a signal comprising:

a) combiner means for combining a plurality of amplified signals to produce a combined amplified signal;

b) combiner power measurement means, operably connected to said combiner means, for measuring the power of said combined amplified signal and producing a combiner power measurement; and

c) at least two signal transmission subsystems, operably connected to said combiner means, each signal transmission subsystem further comprising;

1) amplifier for amplifying a phase-controlled signal and producing one amplified signal of said plurality of amplified signals;

2) subsystem power measurement means for measuring the power of said one amplified signal and producing a subsystem power measurement; and

3) linear digital filter, operably connected to said amplifier, for subjecting a signal to a controlled group delay to produce said phase-controlled signal, wherein said controlled group delay is based on a digital phase control signal.

3. The apparatus of claim 2 wherein said combiner means comprises Wilkinson combiners.

4. The apparatus of claim 2 further comprising control module, operably connected to said combiner power measurement means, to each of said subsystem power measurement means and to each of said linear digital filters, for generating each of said digital phase control signals based on the values of said combiner power measurement and said subsystem power measurements measured in relation to adjustments of said digital phase control signal.

5. The apparatus of claim 4 wherein said combiner means comprises Lange couplers.

6. The apparatus of claim 5 wherein said Lange couplers are operably coupled to said control module and provide signal phase information to said control module, and wherein said digital phase control signals are based on said signal phase information.

7. A process for amplifying a signal comprising the steps of:

a) combining at least two amplified signals to produce a combined amplified signal;

b) measuring the power of said combined amplified signal and producing a combiner power measurement; and

c) generating each of said at least two amplified signals, wherein said step of generating for each amplified signal further comprises;

1) mixing a signal with a digitally phase-controlled mixing signal to produce an upconverted signal;

2) amplifying said upconverted signal to produce one amplified signal of said plurality of amplified signals;

3) measuring the power of said one amplified signal and producing a subsystem power measurement;

4) generating said digitally phase-controlled mixing signal in accordance with a digital phase control signal;

5) adjusting said digital phase control signal based on a combining efficiency measurement; and

6) generating said combining efficiency measurement based on the subsystem power measurement generated from each of said at least two amplified signals and on said combiner power measurement.

8. The process of claim 7 wherein said step of generating said combining efficiency measurement comprises dividing said combiner power measurement by the sum of said subsystem power measurements.

9. The process of claim 7 wherein the mixing of step 1) is analog mixing, and wherein said step of generating said digitally phase-controlled mixing signal further comprises the steps of:

4.1) utilizing a direct digital synthesizer to generate a digital mixing signal having a phase based on said digital phase control signal; and

4.2) performing digital-to-analog conversion of said digital mixing signal to produce said phase-controlled mixing signal.

10. The process of claim 7 wherein the mixing of step 1) is digital mixing, and wherein said step of generating said digitally phase-controlled mixing signal comprises the step of utilizing a direct digital synthesizer to generate a digital mixing signal having a phase based on said digital phase control signal.

11. The process of claim 7 wherein said step of mixing a signal with a digitally phase-controlled mixing signal further comprises the step of applying a gain to said signal based on the subsystem power measurements measured from each of said at least two amplified signals.

12. A process for amplifying a signal comprising the steps of:

a) combining at least two amplified signals to produce a combined amplified signal;

b) measuring the power of said combined amplified signal and producing a combiner power measurement; and

c) generating each of said at least two amplified signals, wherein said step of generating for each amplified signal further comprises;

1) performing linear digital filtering of a signal to produce a group delay equivalent to a phase shift of said signal to produce a phase-controlled signal, wherein said filtering is adjusted such that the magnitude of said phase shift is based on a digital phase control signal;

2) adjusting said digital phase control signal based on a combining efficiency measurement; and

3) generating said combining efficiency measurement based on the subsystem power measurement generated from each of said at least two amplified signals and on said combiner power measurement.

13. A process for amplifying a signal comprising the steps of:

a) generating a first digital phase control signal;

b) using a first phase-controlled oscillator to generate a first phase-controlled mixing signal based on said first digital phase control signal;

c) mixing said first phase-controlled mixing signal with a first input signal to produce a first upconverted signal;

d) amplifying said first upconverted signal to produce a first amplified signal;

e) measuring the power of said first amplified signal to produce a first power measurement signal;

f) generating a second upconverted signal;

g) amplifying said second upconverted signal to produce a second amplified signal;

h) measuring the power of said second amplified signal to produce a second power measurement signal;

i) combining said first amplified signal and said second amplified signal to produce a combined amplified signal;

j) measuring the power of said combined amplified signal to produce a combined power measurement signal;

k) generating a first power combining efficiency signal based on said first power measurement signal, said second power measurement signal, and said combined power measurement signal;

l) adding an offset to said first digital phase control signal to cause modification of said first phase-controlled mixing signal;

m) thereafter generating a second power combining efficiency signal; and

n) where said second power combining efficiency signal is less than said first power combining efficiency signal, subtracting said offset from said first digital phase control signal.

14. The process of claim 13 wherein said first power combining efficiency signal is generated by dividing said combined power measurement signal by the sum of said first power measurement signal and said second power measurement signal.

15. The process of claim 13 wherein said step m) comprises the sub-steps of:

m.1) generating a set of modified measurement signals; and

m.2) generating said second power combining efficiency signal based on said set of modified measurement signals.

16. The process of claim 13 wherein said first input signal and said first phase-controlled mixing signal are analog signals, and wherein said step of mixing said first phase-controlled signal further is analog mixing.

17. The process of claim 13 wherein said sub-step of generating a second upconverted signal further comprises the sub-steps of:

f.1) utilizing a direct digital synthesizer to generate a second analog mixing signal; and

f.2) performing a second analog mixing by multiplying a second analog input signal with said second analog mixing signal to produce a second analog upconverted signal.

18. The process of claim 17 further comprising the step of applying a first analog gain to said first upconverted signal before said step of amplifying said first upconverted signal, and further comprising the step of applying a second analog gain to said second upconverted signal before said step of amplifying said second upconverted signal.

19. The process of claim 18 further comprising the step of adjusting said first analog gain such that said first power measurement signal is approximately equal to said second power measurement signal.

20. The process of claim 15 wherein said set of modified signals comprises a modified combined power measurement signal produced by measuring the power of said combined amplified signal.

21. The process of claim 20 wherein said second power combining efficiency signal is generated by dividing said modified combined power measurement signal by the sum of said first power measurement signal and said second power measurement signal.

22. The process of claim 20 wherein said set of modified signals further comprises a modified first power measurement signal produced by measuring the power of said first amplified signal.

23. The process of claim 22 wherein said set of modified signals further comprises a modified second power measurement signal produced by measuring the power of said second amplified signal.

24. The process of claim 23 wherein said second power combining efficiency signal is generated by dividing said modified combined power measurement signal by the sum of said modified first power measurement signal and said modified second power measurement signal.

25. The process of claim 13 wherein said first input signal and said first phase-controlled mixing signal are digital signals, and wherein said step of mixing said first phase-controlled signal further comprises the sub-steps of:

c.1) performing a first digital mixing by multiplying said first input signal with said first phase-controlled mixing signal to produce a first digital upconverted signal; and

c.2) performing first digital-to-analog conversion of said first digital upconverted signal to produce said first upconverted signal.

26. The process of claim 25 wherein said sub-step of generating a second upconverted signal further comprises the sub-steps of:

f.1) utilizing a direct digital synthesizer to generate a second digital mixing signal;

f.2) performing a second digital mixing by multiplying a second digital input signal with said second digital mixing signal to produce a second digital upconverted signal; and

f.3) performing second digital-to-analog conversion of said second digital upconverted signal to produce said second upconverted signal.

27. The process of claim 26 further comprising the step of applying a first digital gain to said first digital upconverted signal before performing said first digital-to-analog conversion, and further comprising the step of applying a second digital gain to said second digital upconverted signal before performing said second digital-to-analog conversion.

28. The process of claim 27 further comprising the step of generating said first digital gain and said second digital gain based on said first power measurement signal, said second power measurement signal, and said combined power measurement signal.

29. Apparatus for upconverting and amplifying a signal comprising:

combiner for combining a plurality of amplified signals to produce a combined amplified signal; and

at least two signal transmission subsystems, wherein each signal transmission subsystem comprises;

phase-controlled digital oscillator for generating a phase-controlled digital mixing signal, wherein the phase of said phase-controlled digital mixing signal is based on a digital phase control signal;

digital mixer for mixing a digital signal with said phase-controlled digital mixing signal to produce an upconverted signal;

amplifier for amplifying said upconverted signal to produce one amplified signal of said plurality of amplified signals; and

control module for generating each of said digital phase control signals based on a combiner power measurement measured at the output of said combiner.

30. The apparatus of claim 29 further comprising combiner power meter for measuring the power of said combined amplified signal and producing a combiner power measurement.

31. The apparatus of claim 29, wherein each of said signal transmission subsystems further comprises a subsystem power meter for measuring the power of said one amplified signal and producing a subsystem power measurement.

32. The apparatus of claim 29 wherein said control module further measures subsystem power measurements at the output of each amplifier of said at least two signal transmission subsystems.

33. The apparatus of claim 29, wherein said phase-controlled digital oscillator is a direct digital synthesizer.

34. The apparatus of claim 33, wherein each of said signal transmission subsystems further comprises subsystem power meter for generating a subsystem power measurement based on a power measured at the output of said amplifier.

35. The apparatus of claim 34, wherein each of said signal transmission subsystems further comprises further comprises digital gain module for applying a gain to said upconverted signal based on a gain control signal, wherein said control module generates said gain control signal based on said combiner power measurement and said subsystem power measurement.

36. Apparatus for upconverting and amplifying a signal comprising:

combiner for combining a plurality of amplified signals to produce a combined amplified signal; and

at least two signal transmission subsystems, wherein each signal transmission subsystem comprises;

phase-controlled digital oscillator for generating a phase-controlled digital signal, wherein the phase of said phase-controlled digital signal is based on a digital phase control signal;

digital-to-analog converter for receiving a phase-controlled digital signal and producing a phase-controlled analog mixing signal;

analog mixer for mixing an analog information signal with said phase-controlled analog mixing signal to produce an upconverted signal; and

amplifier for amplifying said upconverted signal and producing one amplified signal of said plurality of amplified signals.

37. The apparatus of claim 36 further comprising combiner power meter for measuring the power of said combined amplified signal and producing a combiner power measurement.

38. The apparatus of claim 36, wherein each of said signal transmission subsystems further comprises a subsystem power meter for measuring the power of said one amplified signal and producing a subsystem power measurement.

39. The apparatus of claim 36, wherein said phase-controlled digital oscillator is a direct digital synthesizer.

40. The apparatus of claim 36 further comprising control module, for generating each of said digital phase control signals based on a combiner power measured at the output of said combiner and on subsystem power measurements measured at the output of each amplifier of said at least two signal transmission subsystems.

41. The apparatus of claim 36 further comprising control module for generating each of said digital phase control signals based on a combiner power measurement measured at the output of said combiner.

42. The apparatus of claim 41, wherein each of said signal transmission subsystems further comprises subsystem power meter for generating a subsystem power measurement based on a power measured at the output of said amplifier.

43. The apparatus of claim 42, wherein each of said signal transmission subsystems further comprises further comprises digital gain module for applying a gain to said upconverted signal based on a gain control signal, wherein said control module generates said gain control signal based on said combiner power measurement and said subsystem power measurement.

44. An apparatus comprising:

a first signal transmission subsystem, the first signal transmission subsystem comprising;

a first upconverter configured to upconvert a data signal to provide a first upconverted signal; and

a first amplifier configured to amplify the first upconverted signal to provide a first amplified signal having a first amplified signal phase; and

a second signal transmission subsystem, the second signal transmission subsystem comprising;

a phase-controlled digital oscillator configured to generate a phase-controlled digital mixing signal having a mixing signal phase based on a phase control signal;

a second upconverter configured to upconvert the data signal using the phase-controlled digital mixing signal to provide a second upconverted signal; and

a second amplifier configured to amplify the second upconverted signal to provide a second amplified signal having a second amplified signal phase, wherein the phase control signal is adjusted based on a difference between the first amplified signal phase and the second amplified signal phase.

45. The apparatus of claim 44 wherein the phase-controlled digital oscillator is a direct digital synthesizer.

46. The apparatus of claim 44 further comprising:

a first linear digital filter configured to apply a first controlled group delay to the first upconverted signal; and

a second linear digital filter configured to apply a second controlled group delay to the second upconverted signal.

47. The transmitter of claim 44 further comprising a combiner configured to combine the first amplified signal and the second amplified signal to provide a combined amplified signal.

48. The apparatus of claim 47 wherein the combiner comprises a Wilkinson combiner.

49. The apparatus of claim 47 wherein the combiner comprises a Lange coupler.

50. The apparatus of claim 49 further comprising:

a first subsystem power meter configured to measure an amplitude of the first amplified signal; and

a second subsystem power meter configured to measure an amplitude of the second amplified signal.

51. The apparatus of claim 47 further comprising:

a combiner power meter configured to measure the amplitude of the combined amplified signal to provide a measured combiner power; and

a control module configured to generate the phase control signal based on the measured combiner power.

52. The apparatus of claim 44 further comprising:

a first digital gain module configured to apply a first digital gain to the first upconverted signal; and

a second digital gain module configured to apply a second digital gain to the second upconverted signal.

53. The apparatus of claim 52 wherein the second digital gain module performs spectrum shaping of the second upconverted signal.

54. The apparatus of claim 52 further comprising a control module configured to generate a gain control signal, wherein the second digital gain is based on the gain control signal.

55. The apparatus of claim 44 further comprising:

a linear digital filter configured to apply a controlled group delay to the second upconverted signal.

56. The apparatus of claim 55 further comprising a control module configured to generate a filter control signal, wherein the controlled group delay is based on the filter control signal.