Microwave transmitter and the method for increasing envelope bandwidth

• US 20070018718A1
• Filed: 06/19/2006
• Published: 01/25/2007
• Est. Priority Date: 06/20/2005
• Status: Abandoned Application

• Current Assignee: Industrial Technology Research Institute, National Sun Yat-sen University
• Original Assignee: Industrial Technology Research Institute, National Sun Yat-sen University
• Inventors: Jau, Je-Kuan, Horng, Tzyy-Sheng, Lai, Chang-Ming, Chen, Yuan, Li, Jian-Yu
• Application Number:
  US11/455,046
• Publication Number:
  US 20070018718A1
• Time in Patent Office: Days
• US Class Current: 330/10
• CPC Class Codes: H03F 1/0227 using supply converters

Abstract

The microwave transmitter of the present invention can perform two-terminal dynamic modulation with respect to the voltage supply terminal and the RF input terminal of a RF power amplifier. The microwave transmitter of the present invention comprises a first modulator and a second modulator. The first modulator uses the baseband digital delta-sigma modulation technique to process the envelope signal and outputs this signal to the voltage supply terminal of the RF power amplifier as a supply voltage. The second modulator uses the baseband digital pre-distortion technique to process the IQ-modulated carrier and outputs this signal to the RF input terminal of the RF power amplifier as a RF input signal. Thereby, the RF power amplifier can highly efficiently reconstruct the power-amplified RF modulated carrier without distortion at the RF output terminal. In addition, the baseband digital processing techniques used in the two modulators make the microwave transmitter of the present invention suitable for multi-mode operation.

Claims

1. A transmitter, comprising:

an RF power amplifier, having a power supply terminal, an input terminal and an output terminal;

a first modulator, coupled to the power supply terminal of said RF power amplifier, said first modulator using the digital delta-sigma modulation technique to generate an envelope signal to supply to said power supply terminal; and

a second modulator, coupled to the input terminal of said RF power amplifier, said second modulator using the pre-distortion technique to process and generate an IQ-modulated carrier to supply to said input terminal.

2. The transmitter of claim 1, wherein said first modulator comprises a delta-sigma modulator, a switched amplifier and a low-pass filter.

3. The transmitter of claim 2, wherein said delta-sigma modulator receives the digital envelope signal generated from an envelope generator.

4. The transmitter of claim 3, wherein said envelope generator receives an IQ signal or an output signal generated from a pre-distorter, and said pre-distorter receives an IQ signal.

5. The transmitter of claim 1, further comprising:

an envelope generator, coupled to the input terminal of the first modulator, for generating the corresponding digital envelope signal of the desired modulated signal.

6. The transmitter of claim 5, wherein said first modulator comprises:

a delta-sigma modulator, for receiving the digital envelope signal and modulating it to be a two-stage signal.

7. The transmitter of claim 6, wherein said first modulator comprises:

a switched amplifier for amplifying the two-stage signal, the amplified two-stage signal passing a low-pass filter to reduce to an amplified analog envelope signal for modulating the power supply terminal of said RF power amplifier.

8. The transmitter of claim 6, wherein said delta-sigma modulator is selected from the group consisting of an analog delta-sigma modulator, an analog pulse-width modulator, an analog multi-stage delta-sigma modulator, a digital delta-sigma modulator, a digital pulse-width modulator and a digital multi-stage delta-sigma modulator.

9. The transmitter of claim 5, wherein said first modulator comprises:

a delta-sigma modulator for receiving the digital envelope signal and modulating the digital envelope signal to an at least two-stage signal.

10. The transmitter of claim 6, wherein said first modulator comprises:

an at least one bit control current source, for converting the at least two-stage signal to a controlled current, the controlled current passing a low-pass filter to be the current supply for the power supply terminal.

11. The transmitter of claim 1, wherein said second modulator comprises a pre-distorter, a plurality of digital-to-analog converters and an IQ-modulator.

12. The transmitter of claim 11, wherein said pre-distorter has the circuitry functions including changing the IQ baseband signal, the envelope signal, the phase signal or the amplitude of the RF carrier.

13. The transmitter of claim 1, further comprising:

a delay control unit, for coordinating the synchronization between said first modulator and said second modulator.

14. The transmitter of claim 1, further comprising:

a feedback control unit, for detecting the output terminal of said RF power amplifier to obtain a feedback signal and processing the feedback signal and a digital envelope signal from an envelope generator with pre-distortion to modulate the gain of said input terminal.

15. The transmitter of claim 14, wherein said feedback control unit comprises:

an envelope detector, for detecting said output terminal to generate the feedback signal;

an analog-to-digital converter, for digitizing the feedback signal; and

a pre-distorter, for receiving the digitized feedback signal and the digital envelope signal from the envelope generator to control a tunable gain amplifier, the tunable gain amplifier coupled to said input terminal.

16. The transmitter of claim 1, wherein said power supply terminal receives a low-frequency envelope signal.

17. The transmitter of claim 1, wherein said input terminal receives a phase-modulated carrier that is provided with a time-varying envelope.

18. The transmitter of claim 1, wherein said RF power amplifier is selected from the group consisting of class-A, class-B, class-AB, class-C, class-D, class-E or class-F amplifier circuits.

19. A modulation method for an RF power amplifier, applying to a transmitter, the modulation method for an RF power amplifier comprising:

generating an envelope signal with the digital delta-sigma modulation technique, to modulate the power supply terminal of said RF power amplifier; and

processing and generating an IQ-modulated carrier with pre-distortion technique, to modulate the input terminal of said RF power amplifier.

20. The modulation method for an RF power amplifier of claim 19, further comprising:

processing the corresponding envelope signal of the desired modulated signal with a digital delta-sigma modulator.

21. The modulation method for an RF power amplifier of claim 19, further comprising:

generating a phase-modulated and envelope-modulated driving signal with a combination of a pre-distorter, a plurality of digital-to-analog converters and an IQ-modulator.

22. The modulation method for an RF power amplifier of claim 19, further comprising:

coordinating the synchronization between a first modulator and a second modulator with a delay control.

23. The modulation method for an RF power amplifier of claim 19, further comprising:

detecting the output terminal of said RF power amplifier to obtain a feedback signal; and

processing the feedback signal with pre-distortion to modulate the gain of said input terminal.

24. The modulation method for an RF power amplifier of claim 19, further comprising:

controlling an at least one bit control current source with at least two-stage modulation, to convert the envelope signal to the current supply for said power supply terminal.

25. A transmitter, comprising:

a first modulator, receiving the envelope signal for the desired modulated signal and modulating it to be a two-stage signal, to generate a low-frequency envelope signal for the desired modulated signal;

a second modulator, receiving the desired modulated signal and processing it with pre-distortion, to generate a phase-modulated carrier that is characterized by a time-varying envelope; and

an RF power amplifier, receiving the low-frequency envelope signal for the desired modulated signal as the voltage supply for the RF power amplifier, and receiving the phase-modulated carrier that is characterized by a time-varying envelope as an RF input signal for the RF power amplifier, to generate an amplified RF modulated signal.

26. The transmitter of claim 25, wherein said first modulator comprises a delta-sigma modulator, a switched amplifier and a low-pass filter.

27. The transmitter of claim 26, wherein said delta-sigma modulator is selected from the group consisting of an analog delta-sigma modulator, an analog pulse-width modulator, an analog multi-stage delta-sigma modulator, a digital delta-sigma modulator, a digital pulse-width modulator and a digital multi-stage delta-sigma modulator.

28. The transmitter of claim 25, further comprising:

an envelope generator, for generating the corresponding digital envelope signal of the desired modulated signal and supplying the digital envelope signal to said first modulator.

29. The transmitter of claim 25, wherein said second modulator comprises a pre-distorter, a plurality of digital-to-analog converters and an IQ-modulator.

30. The transmitter of claim 29, wherein said pre-distorter has the circuitry functions including changing the IQ baseband signal, the envelope signal, the phase signal or the amplitude of the RF carrier.

31. The transmitter of claim 25, wherein said RF power amplifier is selected from the group consisting of class-A, class-B, class-AB, class-C, class-D, class-E or class-F amplifier circuits.

32. A baseband processor, used in a transmitter, the baseband processor comprising:

an envelope generator, for generating the corresponding digital envelope signal of the desired modulated signal;

a delta-sigma modulator, for receiving the digital envelope signal and modulating it to be a two-stage signal;

a switched amplifier for amplifying the two-stage signal;

a low-pass filter, for receiving the amplified two-stage signal and reducing it to an amplified analog envelope signal; and

a pre-distorter, for compensating the nonlinear relation between the input and output signals of the microwave transmitter, thereby improving the parameters such as the modulation accuracy and the linearity.

33. The baseband processor of claim 32, wherein said delta-sigma modulator is selected from the group consisting of an analog delta-sigma modulator, an analog pulse-width modulator, an analog multi-stage delta-sigma modulator, a digital delta-sigma modulator, a digital pulse-width modulator and a digital multi-stage delta-sigma modulator.

34. The baseband processor of claim 32, wherein said pre-distorter has the circuitry functions including changing the IQ baseband signal, the envelope signal, the phase signal or the amplitude of the RF carrier.

35. The baseband processor of claim 32, wherein said transmitter comprises a transceiver chip, the transceiver chip coupled to said baseband processor for operation.

36. The baseband processor of claim 32, further comprising:

a plurality of digital-to-analog converters, for converting the output signal of said pre-distorter to the corresponding analog signal.

37. The baseband processor of claim 32, wherein said envelope generator, said delta-sigma modulator and said pre-distorter are all realized with the baseband digital processing technique.

38. The baseband processor of claim 32, wherein said switched amplifier and said low-pass filter are both realized with the baseband analog signal processing technique.

39. The baseband processor of claim 36, wherein said digital-to-analog converters are realized with the baseband mixed signal processing technique.

40. A wireless transceiver chip, having a baseband processor, an RF processor and an RF power amplifier, the baseband processor comprising:

an envelope generator, for generating the corresponding digital envelope signal of the desired modulated signal;

a delta-sigma modulator, for receiving the digital envelope signal and modulating it to be a two-stage signal;

a switched amplifier for amplifying the two-stage signal;

a low-pass filter, for receiving the amplified two-stage signal and reducing it to an amplified analog envelope signal, the analog envelope signal supplied to said RF power amplifier; and

a pre-distorter, for compensating the nonlinear relation between the input and output signals of the microwave transmitter.

41. The wireless transceiver chip of claim 40, wherein said delta-sigma modulator of the baseband processor is selected from the group consisting of an analog delta-sigma modulator, an analog pulse-width modulator, an analog multi-stage delta-sigma modulator, a digital delta-sigma modulator, a digital pulse-width modulator and a digital multi-stage delta-sigma modulator.

42. The wireless transceiver chip of claim 40, wherein said pre-distorter of the baseband processor has the circuitry functions including changing the IQ baseband signal, the envelope signal, the phase signal or the amplitude of the RF carrier.

43. The wireless transceiver chip of claim 40, further comprising:

a plurality of digital-to-analog converters, for converting the output signal of said pre-distorter to the corresponding analog signal.

44. The wireless transceiver chip of claim 40, wherein said envelope generator, said delta-sigma modulator and said pre-distorter are all realized with the baseband digital processing technique.

45. The wireless transceiver chip of claim 40, wherein said switched amplifier and said low-pass filter are both realized with the baseband analog signal processing technique.

46. The wireless transceiver chip of claim 43, wherein said digital-to-analog converters are realized with the baseband mixed signal processing technique.

47. The wireless transceiver chip of claim 40, wherein said RF power amplifier is selected from the group consisting of class-A, class-B, class-AB, class-C, class-D, class-E or class-F amplifier circuits.

48. The wireless transceiver chip of claim 40, wherein the error vector magnitude (EVM) for measuring the modulation accuracy, the adjacent channel power ratio (ACPR) for measuring the linearity, and the conversion efficiency (ConvEff) of DC power to RF power for measuring the transmitter efficiency are all independent of the output power of said RF power amplifier.

49. A transmitter, comprising:

an RF power amplifier, having a power supply terminal, an input terminal and an output terminal; and

a first modulator, coupled to the power supply terminal of said RF power amplifier and controlling the output power of the RF power amplifier, the first modulator comprising;

an envelope generator, for receiving an IQ signal to generate a digital envelope signal;

a delta-sigma modulator, for receiving the digital envelope signal and modulating it to be an at least two-stage signal; and

an at least one bit control current source, for converting the at least two-stage signal to a controlled current, the controlled current passing a low-pass filter to be the current supply for the RF power amplifier.

50. The transmitter of claim 49, further comprising:

a second modulator, coupled to the input terminal of said RF power amplifier, said second modulator receiving an IQ signal, to generate an IQ-modulated carrier to supply to said input terminal.

51. The transmitter of claim 50, further comprising:

a delay control unit, for coordinating the synchronization between said first modulator and said second modulator.

52. The transmitter of claim 49, further comprising:

a feedback control unit, for detecting the output terminal of said RF power amplifier to obtain a feedback signal and processing the feedback signal and the digital envelope signal from the envelope generator with pre-distortion to modulate the gain of said input terminal.

53. The transmitter of claim 52, wherein said feedback control unit comprising:

an envelope detector, for detecting said output terminal to generate the feedback signal;

an analog-to-digital converter, for digitizing the feedback signal; and

a pre-distorter, for receiving the digitized feedback signal and the digital envelope signal from the envelope generator to control a tunable gain amplifier, the tunable gain amplifier coupled to said input terminal.