Linear amplification systems and methods using more than two constant length vectors

• US 6,311,046 B1
• Filed: 12/10/1998
• Issued: 10/30/2001
• Est. Priority Date: 04/02/1998
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Dent, Paul Wilkinson
• Primary Examiner(s): Le, Thanh Cong
• Assistant Examiner(s): Woldetatios, Yemane
• Application Number:
  US09/209,104
• Time in Patent Office: 1,055 Days
• Field of Search: 455/102, 455/103, 455/115, 455/126, 455/91, 455/13.4, 455/127, 455/129, 455/116, 455/139, 455/140, 455/141, 455/108, 455/118, 455/42, 455/110, 455/522, 330/124 R, 330/295, 330/84, 330/151, 330/286, 332/144, 375/295, 375/261, 375/298, 375/269, 375/280, 375/308
• US Class Current: 455/91
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• 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 2200/336 A I/Q, i.e. phase quadrature, modulator or demodulator being used in an amplifying circuit
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2200/541 Transformer coupled at the output of an amplifier
• CPC Class Codes: H03F 2203/21106 An input signal being distributed in parallel over the inputs of a plurality of power amplifiers
• CPC Class Codes: H03F 2203/21142 Output signals of a plurality of power amplifiers are parallel combined to a common output
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence
• CPC Class Codes: H03F 3/24 of transmitter output stages

Abstract

An input signal of varying amplitude and varying phase is converted into more than two signals of constant amplitude and controlled phase. Each of the more than two signals of constant amplitude and controlled phase is then separately amplified in separate amplifiers. The separately amplified more than two signals of constant amplitude and controlled phase are then combined to produce an output signal that is an amplification of the input signal at the desired power level. When converting the input signal into more than two signals, the phase of each of the more than two signals of constant amplitude and controlled phase is controlled to produce the output signal that is an amplification of the input signal at the desired power level. According to another aspect, a signal of varying amplitude and varying phase is generated from a plurality of constant amplitude varying phase signals, the sum of which is the signal of varying amplitude and varying phase. An IQ waveform generator generates a cosine carrier modulation waveform I(t) and a sine carrier modulation waveform Q(t) from the signal of varying amplitude and varying phase. A function generator generates a complimentary waveform Q′(t) from the cosine carrier modulation waveform I(t) such that the sum of squares of I(t) and Q′(t) is constant. A first modulator modulates a cosine carrier signal with I(t) to obtain a first modulated cosine carrier. A second modulator modulates a sine carrier signal with Q′(t) to obtain a first modulated sine carrier. A circuit such as a butterfly circuit forms the sum and difference of the first modulated cosine carrier and the first modulated sine carrier to obtain the constant amplitude varying phase signals.

Claims

1. A method for generating from a signal of varying amplitude and varying phase, a plurality of constant amplitude varying phase signals, the sum of which is the signal of varying amplitude and varying phase, comprising the steps of:

generating a cosine carrier modulation waveform I(t) and a sine carrier modulation waveform Q(t) from the signal of varying amplitude and varying phase;

generating a complementary waveform Q′

(t) from the cosine carrier modulation waveform I(t) such that the sum of the squares of I(t) and Q′

(t) is constant;

modulating a cosine carrier signal with I(t) to obtain a first modulated cosine carrier;

modulating a sine carrier signal with Q′

(t) to obtain a first modulated sine carrier; and

forming a sum and difference of the first modulated cosine carrier and the first modulated sine carrier to obtain the constant amplitude varying phase signals.

2. A method according to claim 1 further comprising the steps of:

generating a complementary waveform I′

(t) from the sine carrier modulation waveform Q(t) such that the sum of the squares of I′

(t) and Q(t) is constant;

modulating a cosine carrier signal with I′

(t) to obtain a second modulated cosine carrier;

modulating a sine carrier signal with Q(t) to obtain a second modulated sine carrier; and

forming a sum and difference of the second modulated cosine carrier and the second modulated sine carrier to obtain a second set of constant amplitude varying phase signals.

3. A system for generating from a signal of varying amplitude and varying phase, a plurality of constant amplitude varying phase signals, the sum of which is the signal of varying amplitude and varying phase, the system comprising:

means for generating a cosine carrier modulation waveform I(t) and a sine carrier modulation waveform Q(t) from the signal of varying amplitude and varying phase;

means for generating a complementary waveform Q′

(t) from the cosine carrier modulation waveform I(t) such that the sum of the squares of I(t) and Q′

(t) is constant;

means for modulating a cosine carrier signal with I(t) to obtain a first modulated cosine carrier;

means for modulating a sine carrier signal with Q′

(t) to obtain a first modulated sine carrier; and

means for forming a sum and difference of the first modulated cosine carrier and the first modulated sine carrier to obtain the constant amplitude varying phase signals.

4. A system according to claim 3 further comprising:

means for generating a complementary waveform I′

(t) from the sine carrier modulation waveform Q(t) such that the sum of the squares of I′

(t) and Q(t) is constant;

means for modulating a cosine carrier signal with I′

(t) to obtain a second modulated cosine carrier;

means for modulating a sine carrier signal with Q(t) to obtain a second modulated sine carrier; and

means for forming a sum and difference of the second modulated cosine carrier and the second modulated sine carrier to obtain a second set of constant amplitude varying phase signals.

5. A system for generating from a signal of varying amplitude and varying phase, a plurality of constant amplitude varying phase signals, the sum of which is the signal of varying amplitude and varying phase, the system comprising:

an IQ waveform generator that generates a cosine carrier modulation waveform I(t) and a sine carrier modulation waveform Q(t) from the signal of varying amplitude and varying phase;

a function generator that generates a complementary waveform Q′

(t) from the cosine carrier modulation waveform I(t) such that the sum of the squares of I(t) and Q′

(t) is constant;

a first modulator that modulates a cosine carrier signal with I(t) to obtain a first modulated cosine carrier;

a second modulator that modulates a sine carrier signal with Q′

(t) to obtain a first modulated sine carrier; and

a circuit that forms a sum and difference of the first modulated cosine carrier and the first modulated sine carrier to obtain the constant amplitude varying phase signals.

6. A system according to claim 5 further comprising:

a second function generator that generates a complementary waveform I′

(t) from the sine carrier modulation waveform Q(t) such that the sum of the squares of I′

(t) and Q(t) is constant;

a third modulator that modulates a cosine carrier signal with I′

(t) to obtain a second modulated cosine carrier;

a fourth modulator that modulates a sine carrier signal with Q(t) to obtain a second modulated sine carrier; and

a second circuit that forms a sum and difference of the second modulated cosine carrier and the second modulated sine carrier to obtain a second set of constant amplitude varying phase signals.

7. A method for generating a radio frequency signal at a desired transmit power level, the radio frequency signal being modulated in phase and amplitude with an information source signal, the method comprising:

generating from the information source signal a complex baseband signal representative of the phase and amplitude modulation, the complex baseband signal comprising an in-phase signal and a quadrature signal;

using the in-phase and quadrature signals to modulate a radio carrier frequency to produce more than two modulated radio frequency signals of constant amplitude and varying phase;

separately amplifying each of the more than two modulated radio frequency signals; and

combining the more than two amplified modulated radio frequency signals to produce the desired radio frequency signal that is modulated in phase and amplitude with the information source signal at the desired transmit power level.

8. A method according to claim 7 wherein the more than two modulated radio frequency signals of constant amplitude and varying phase are four signals, a first pair of the four signals being modulated in phase only in dependence on the in-phase signal and the second pair of the four signals being modulated in phase only in dependence on the quadrature signal.

9. A method according to claim 8 wherein a sub-combination of the first pair of signals is a radio frequency signal modulated in amplitude according to the in-phase signal and a sub-combination of the second pair of signals is a radio frequency signal modulated in amplitude according to the quadrature signal, and the sub-combinations are in quadrature and combine to produce the radio frequency signal that is modulated in phase and amplitude with the information signal at the transmit power level.

10. A method according to claim 9 wherein the phases of the first pair of signals are modulated in a counter-rotating manner in dependence only on the in-phase signal and the phases of the second pair of signals are modulated in a counter-rotating manner in dependence only on the quadrature signal.

11. A method according to claim 7 wherein the separately amplifying comprises separately amplifying each of the more than two signals of constant amplitude and controlled phase in separate saturated amplifiers.

12. A method according to claim 7 wherein the combining comprises series connecting the separately amplified signals with a load impedance such that the load impedance receives the sum of the voltages of the separately amplified signals.

13. A method according to claim 7 in which the combining comprises connecting each of the separately amplified signals via a quarter wavelength transmission line or discrete component equivalent thereof to a single terminal of a load impedance such that the load impedance receives a signal current proportional to a sum of the separately amplified signals.

14. A method according to claim 13 in which the discrete equivalent to the quarter wavelength lines comprises an inductance that connects each of the separately amplified signals to the load terminal.

15. A method according to claim 13 wherein the more than two quarter wavelength transmission line equivalent networks are more than two Pi-networks comprising inductors and capacitors.

16. A method according to claim 15 wherein the capacitors include output capacitors that are combined in parallel.

17. A method according to claim 15 wherein the capacitors include input capacitors that include the output capacitance of the associated separate amplifiers.

18. A method according to claim 7 wherein the modulating comprises phase modulating each of the more than two signals of constant amplitude in dependence on the in-phase and quadrature signals.

19. A method according to claim 7 wherein the modulating comprises quadrature modulating each of the more than two signals of constant amplitude in dependence on the in-phase and quadrature signals.

20. A method according to claim 7 wherein the modulating comprises using a separate phase locked loop to filter each of the more than two signals.

21. A method according to claim 8 further comprising:

generating a signal Q′

complementary to the in-phase signal such that the sum of the squares of the in-phase signal and Q′

is constant;

modulating a cosine signal at the radio carrier frequency with the in-phase signal and a sine signal with the Q′

signal to produce a modulated cosine and a modulated sine signal;

forming the first pair of signals as the sum and the difference of the modulated cosine and modulated sine signal;

generating a signal I′

complementary to the quadrature signal such that the sum of the squares of I′ and

the quadrature signal is constant;

modulating a cosine signal at the radio carrier frequency with the I′

signal and a sine signal with the quadrature signal, to produce a modulated cosine and a modulated sine signal; and

forming the second pair of signals as the sum and the difference of the modulated cosine and modulated sine signals.

22. A system for generating a radio frequency signal at a desired transmit power level, the radio frequency signal being modulated in phase and amplitude with an information source signal, the system comprising:

means for generating from the information source signal a complex baseband signal representative of the phase and amplitude modulation, the complex baseband signal comprising an in-phase signal and a quadrature signal;

means for modulating a radio carrier frequency using the in-phase and quadrature signals to produce more than two modulated radio frequency signals of constant amplitude and varying phase;

means for separately amplifying each of the more than two modulated radio frequency signals; and

means for combining the more than two amplified modulated radio frequency signals to produce the desired radio frequency signal that is modulated in phase and amplitude with the information source signal at the desired transmit power level.

23. A system according to claim 22 wherein the more than two modulated radio frequency signals of constant amplitude and varying phase are four signals, a first pair of the four signals being modulated in phase only in dependence on the in-phase signal and the second pair of the four signals being modulated in phase only in dependence on the quadrature signal.

24. A system according to claim 23 wherein a sub-combination of the first pair of signals is a radio frequency signal modulated in amplitude according to the in-phase signal and a sub-combination of the second pair of signals is a radio frequency signal modulated in amplitude according to the quadrature signal, and the sub-combinations are in quadrature and combine to produce the radio frequency signal that is modulated in phase and amplitude with the information signal at the transmit power level.

25. A system according to claim 24 wherein the phases of the first pair of signals are modulated in a counter-rotating manner in dependence only on the in-phase signal and the phases of the second pair of signals are modulated in a counter-rotating manner in dependence only on the quadrature signal.

26. A system according to claim 22 wherein the means for separately amplifying comprises means for separately amplifying each of the more than two signals of constant amplitude and controlled phase in separate saturated amplifiers.

27. A system according to claim 22 wherein the means for combining comprises means for connecting the separately amplified signals in series with a load impedance such that the load impedance receives the sum of the voltages of the separately amplified signals.

28. A system according to claim 22 wherein the means for combining comprises means for connecting each of the separately amplified signals via a quarter wavelength transmission line or discrete component equivalent thereof to a single terminal of a load impedance such that the load impedance receives a signal current proportional to a sum of the separately amplified signals.

29. A system according to claim 28 wherein the discrete equivalent to the quarter wavelength lines comprises means for inductively connecting each of the separately amplified signals to the load terminal.

30. A system according to claim 28 wherein the more than two quarter wavelength transmission line equivalent networks are more than two Pi-networks comprising inductors and capacitors.

31. A system according to claim 30 wherein the capacitors include output capacitors that are combined in parallel.

32. A system according to claim 31 wherein the capacitors include input capacitors that include the output capacitance of the associated means for separately amplifying.

33. A system according to claim 22 wherein the means for modulating comprises means for phase modulating each of the more than two signals of constant amplitude in dependence on the in-phase and quadrature signals.

34. A system according to claim 22 wherein the means for modulating comprises means for quadrature modulating each of the more than two signals of constant amplitude in dependence on the in-phase and quadrature signals.

35. A system according to claim 22 wherein the means for modulating comprises using a separate phase locked loop to filter each of the more than two signals.

36. A system according to claim 23 further comprising:

means for generating a signal Q′

complementary to the in-phase signal such that the sum of the squares of the in-phase signal and Q′

is constant;

means for modulating a cosine signal at the radio carrier frequency with the in-phase signal and a sine signal with the Q′

signal to produce a modulated cosine and a modulated sine signal;

means for forming the first pair of signals as the sum and the difference of the modulated cosine and modulated sine signal;

means for generating a signal I′

complementary to the quadrature signal such that the sum of the squares of I′ and

the quadrature signal is constant;

means for modulating a cosine signal at the radio carrier frequency with the I′

signal and a sine signal with the quadrature signal, to produce a modulated cosine and a modulated sine signal; and

means for forming the second pair of signals as the sum and the difference of the modulated cosine and modulated sine signals.

37. A system for generating a radio frequency signal at a desired transmit power level, the radio frequency signal being modulated in phase and amplitude with an information source signal, the system comprising:

a generator this is configured to generate from the information source signal a complex baseband signal representative of the phase and amplitude modulation, the complex baseband signal comprising an in-phase signal and a quadrature signal;

a modulator that is configured to modulate a radio carrier frequency using the in-phase and quadrature signals to produce more than two modulated radio frequency signals of constant amplitude and varying phase;

more than two amplifiers, a respective one of which is configured to separately amplify a respective one of the more than two modulated radio frequency signals; and

a combining network that is configured to combine the more than two amplified modulated radio frequency signals to produce the desired radio frequency signal that is modulated in phase and amplitude with the information source signal at the desired transmit power level.

38. A system according to claim 37 wherein the more than two modulated radio frequency signals of constant amplitude and varying phase are four signals, a first pair of the four signals being modulated in phase only in dependence on the in-phase signal and the second pair of the four signals being modulated in phase only in dependence on the quadrature signal.

39. A system according to claim 38 wherein a sub-combination of the first pair of signals is a radio frequency signal modulated in amplitude according to the in-phase signal and a sub-combination of the second pair of signals is a radio frequency signal modulated in amplitude according to the quadrature signal, and the sub-combinations are in quadrature and combine to produce the radio frequency signals that are modulated in phase and amplitude with the information signal at the transmit power level.

40. A system according to claim 39 wherein the phases of the first pair of signals are modulated in a counter-rotating manner in dependence only on the in-phase signal and the phases of the second pair of signals are modulated in a counter-rotating manner in dependence only on the quadrature signal.

41. A system according to claim 37 wherein the more than two amplifiers are more than two saturated amplifiers.

42. A system according to claim 37 wherein the combining network comprises more than two transformers each having a primary winding and a secondary winding, a respective primary winding being coupled to a respective one of the more than two amplifiers, the secondary windings being series-coupled to produce the radio frequency signal.

43. A system according to claim 37 wherein the combining network comprises more than two quarter wavelength transmission lines or discrete component equivalents thereof, a respective one of which is connected between a respective one of the more than two amplifiers and a single terminal of a load impedance such that the load impedance receives a signal current proportional to a sum of the separately amplified signals.

44. A system according to claim 43 wherein the discrete equivalent to the quarter wavelength lines comprises an inductance that is configured to connect each of the separately amplified signals to the load terminal.

45. A system according to claim 43 wherein the more than two quarter wavelength transmission line equivalent networks are more than two Pi-networks comprising inductors and capacitors.

46. A system according to claim 45 wherein the capacitors include output capacitors that are combined in parallel.

47. A system according to claim 45 wherein the capacitors include input capacitors that include the output capacitance of the associated separate amplifiers.

48. A system according to claim 37 wherein the modulator comprises a phase modulator that is configured to modulate each of the more than two signals of constant amplitude in dependence on the in-phase and quadrature signals.

49. A system according to claim 37 wherein the modulator comprises a quadrature modulator that is configured to modulate each of the more than two signals of constant amplitude in dependence on the in-phase and quadrature signals.

50. A system according to claim 37 wherein the modulator comprises a separate phase locked loop to filter each of the more than two signals.

51. A system according to claim 38 further comprising:

a first generator that is configured to generate a signal Q′

complementary to the in-phase signal such that the sum of the squares of the in-phase signal and Q′

is constant;

a first modulator that is configured to modulate a cosine signal at the radio carrier frequency with the in-phase signal and a sine signal with the Q′

signal to produce a modulated cosine and a modulated sine signal;

a first circuit that is configured to form the first pair of signals as the sum and the difference of the modulated cosine and modulated sine signal;

a second generator that is configured to generate a signal I′

complementary to the quadrature signal such that the sum of the squares of I′ and

the quadrature signal is constant;

a second modulator that is configured to modulate a cosine signal at the radio carrier frequency with the I′

signal and a sine signal with the quadrature signal, to produce a modulated cosine and a modulated sine signal; and

a second circuit that is configured to form the second pair of signals as the sum and the difference of the modulated cosine and modulated sine signals.