Mobile wireless communications device with separate In-phase (I) and Quadrature (Q) phase power amplification and power amplifier pre-distortion and IQ balance compensation

• US 8,223,885 B2
• Filed: 02/19/2009
• Issued: 07/17/2012
• Est. Priority Date: 02/19/2009
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Zhu, Lizhong, Mankaruse, George, Corrigan, Michael, Jarmuszewski, Perry, Kravets, Oleksiy, Nickerson, Kent, Sangary, Nagula
• Primary Examiner(s): LEE, SIU M
• Application Number:
  US12/388,532
• Publication Number:
  US 20100208848A1
• Time in Patent Office: 1,244 Days
• Field of Search: 375/295, 375/296, 375/297
• US Class Current: 375/296
• CPC Class Codes: H04L 1/0035 evaluation of received explicit signalling
• CPC Class Codes: H04L 27/2089 with unbalanced quadrature channels
• CPC Class Codes: H04L 27/364 Arrangements for overcoming imperfections in the modulator, e.g. quadrature error or unbalanced I and Q levels
• CPC Class Codes: H04L 27/367 using predistortion

Abstract

A communications device, in one aspect as a portable wireless communications device, includes an in-phase modulator and power amplifier that receives a baseband I signal and modulates and amplifies the I signal. A quadrature modulator and power amplifier receives a baseband Q signal and modulates and amplifies the Q signal. A power combiner sums and outputs the I and Q signals. An I demodulator circuit receives a signal fed back from the I power amplifier and demodulates the fed back signal to produce demodulated I signals. A Q demodulator circuit receives a signal fed back from the Q power amplifier and demodulates the fed back signal to produce demodulated Q signals. A processor compares the digital, baseband I and Q signals with a demodulated I and Q signals to compensate for amplitude, frequency and phase modulation errors.

Claims

1. A communications device, comprising:

an In-phase (I) circuit comprising an In-phase modulator and mixer circuit and an I power amplifier circuit that receives a digital, baseband I signal and modulates and amplifies the I signal;

a Quadrature (Q) circuit comprising a Quadrature modulator and mixer circuit and a Q power amplifier circuit that receives a digital, baseband Q signal and modulates and amplifies the Q signal;

a power combiner that receives the separately amplified I and Q signals and sums and outputs the I and Q signals as a combined I and Q signal;

an I demodulator circuit that receives a signal feedback from the I power amplifier and demodulates the feedback signal to produce demodulated I signals;

a Q demodulator circuit that receives a signal feedback from the Q power amplifier and demodulates the feedback signal to produce demodulated Q signals; and

a processor that compares the digital, baseband I and Q signals with the demodulated I and Q signals to compensate for amplitude, frequency and phase modulation errors wherein I and Q signal inputs are isolated from the combined I and Q signal to enhance antenna matching and transmit radiated power (TRP) and reduce harmonic emission from the respective I and Q power amplifier circuits.

2. The communications device according to claim 1, wherein said processor predistorts the digital baseband I and Q signals fed to the I and Q circuits to aid in compensating for the amplitude, frequency and phase modulation errors.

3. The communications device according to claim 1, wherein said respective In-phase modulator and mixer circuit receives I_I and I_Q input signals to produce an I signal to said I power amplifier and said Quadrature modulator and mixer circuit receives Q_I and Q_Q input signals to produce a Q signal to the Q power amplifier.

4. The communications device according to claim 3, wherein said In-phase modulator and mixer circuit comprises a respective I_I mixer and I_Q mixer that receives respective I_I and I_Q signals and a frequency divider circuit associated with the I_I mixer and I_Q mixer for imparting a ninety degree phase shift and an I summer for receiving signals from the mixers and producing an I signal.

5. The communications device according to claim 3, wherein said Quadrature modulator and mixer circuit comprises a respective Q_I mixer and Q_Q mixer that receives respective Q_I and Q_Q signals and a frequency divider circuit associated with the Q_I mixer and Q_Q mixer for imparting a ninety degree phase shift and a Q summer for receiving signals from the mixers and producing a Q signal.

6. The communications device according to claim 1, wherein said processor outputs control signals for controlling each of said power amplifier circuits and control respective biasing in each power amplifier circuit and adjusts amplitude of a respective I or Q signal.

7. The communications device according to claim 1, wherein each of said I and Q demodulator circuits comprise mixers and a frequency divider associated therewith for imparting a ninety degree phase shift.

8. The communications device according to claim 1, and further comprising an I/Q demodulator circuit connected to the processor that receives a signal from the output of the power combiner to aid in determining the amplitude, frequency and phase modulation errors.

9. The communications device according to claim 1, and further comprising a power detector connected to the processor that receives a signal from the output of the power combiner and outputs a signal that is compared with an original power for compensating for the amplitude error.

10. The communications device according to claim 1, wherein said power combiner comprises about a 3 dB power combiner.

11. The communications device according to claim 1, wherein said power combiner comprises a quadrature hybrid power combiner.

12. A mobile wireless communications device, comprising:

a housing;

an antenna carried by the housing;

at least one circuit board carried by the housing and including radio frequency (RF) circuitry carried by the at least one circuit board and comprising a transceiver connected to said antenna through which RF communications signals are transmitted and received, and a processor carried by the at least one circuit board and operative with the RF circuitry, wherein said transceiver further comprises an In-phase and Quadrature (I/Q) modulation and power amplification circuit comprising

an In-phase (I) circuit comprising an In-phase modulator and mixer circuit and an I power amplifier circuit that receives a digital, baseband I signal and modulates and amplifies the I signal;

a Quadrature (Q) circuit comprising a Quadrature modulator and mixer circuit and a Q power amplifier circuit that receives a digital, baseband Q signal and modulates and amplifies the Q signal;

a power combiner that receives the separately amplified I and Q signals and sums and outputs the I and Q signals as a combined I and Q signal;

an I demodulator circuit that receives a signal feedback from the I power amplifier and demodulates the feedback signal to produce demodulated I signals;

a Q demodulator circuit that receives a signal feedback from the Q power amplifier and demodulates the feedback signal to produce demodulated Q signals; and

said processor comparing the digital, baseband I and Q signals with the demodulated I and Q signals to compensate for amplitude, frequency and phase modulation errors wherein I and Q signal inputs are isolated from the combined I and Q signal to enhance antenna matching and transmit radiated power (TRP) and reduce harmonic emission from the respective I and Q power amplifier circuits.

13. The mobile wireless communications device according to claim 12, wherein said processor predistorts the digital baseband I and Q signals fed to the I and Q circuits to aid in compensating for the amplitude, frequency and phase modulation errors.

14. The mobile wireless communications device according to claim 12, wherein said respective In-phase modulator and mixer circuit receives I_I and I_Q input signals to produce an I signal to said I power amplifier and said Quadrature modulator and mixer circuit receives Q_I and Q_Q input signals to produce a Q signal to the Q power amplifier.

15. The mobile wireless communications device according to claim 14, wherein said In-phase modulator and mixer circuit comprises a respective I_I mixer and I_Q mixer that receives respective I_I and I_Q signals and a frequency divider circuit associated with the I_I mixer and I_Q mixer for imparting a ninety degree phase shift and an I summer for receiving signals from the mixers and producing an I signal.

16. The mobile wireless communications device according to claim 14, wherein said Quadrature modulator and mixer circuit comprises a respective Q_I mixer and Q_Q mixer that receives respective Q_I and Q_Q signals and a frequency divider circuit associated with the Q_I mixer and Q_Q mixer for imparting a ninety degree phase shift and a Q summer for receiving signals from the mixers and producing a Q signal.

17. The mobile wireless communications device according to claim 12, wherein said processor outputs control signals for controlling each of said power amplifier circuits and control respective biasing in each power amplifier circuit and adjusts amplitude of a respective I or Q signal.

18. The mobile wireless communications device according to claim 12, wherein each of said I and Q demodulator circuits comprise mixers and a frequency divider associated therewith for imparting a ninety degree phase shift.

19. The mobile wireless communications device according to claim 12, and further comprising an I/Q demodulator circuit connected to the processor that receives a signal from the output of the power combiner to aid in determining the amplitude, frequency and phase modulation errors.

20. The mobile wireless communications device according to claim 12, and further comprising a power detector connected to the processor that receives a signal from the output of the power combiner and outputs a signal that is compared with an original power for compensating for the amplitude error.

21. The mobile wireless communications device according to claim 12, wherein said power combiner comprises about a 3 dB power combiner.

22. The mobile wireless communications device according to claim 12, wherein said power combiner comprises a quadrature hybrid power combiner.

23. The mobile wireless communications device according to claim 12, wherein said RF circuitry is operative for generating Global Systems for Mobile (GSM) packet bursts.

24. A method of operating a mobile wireless communications device, which comprises:

providing a housing, an antenna mounted within the housing, at least one circuit board carried by the housing and including radio frequency (RF) circuitry carried by the at least one circuit board and comprising a transceiver connected to said antenna through which RF communications signals are transmitted and received;

processing RF communications signals in an In-phase (I) circuit comprising an In-phase modulator and mixer circuit and an I power amplifier circuit that receives a digital, baseband I signal and modulates and amplifies the I signal and in a Quadrature (Q) circuit comprising a Quadrature modulator and mixer circuit and a Q power amplifier circuit that receives a digital, baseband Q signal and modulates and amplifies the Q signal;

power combining the separately amplified I and Q signals;

receiving a signal feedback from the I power amplifier and demodulating the feedback signal to produce demodulated I signals;

receiving a signal feedback from the Q power amplifier and demodulating the feedback signal to produce demodulated Q signals; and

comparing the digital, baseband I and Q signals with the demodulated I and Q signals within a processor to determine amplitude, frequency and phase modulation errors wherein I and Q signal inputs are isolated from the combined I and Q signal to enhance antenna matching and transmit radiated power (TRP) and reduce harmonic emission from the respective I and Q power amplifier circuits.

25. The method according to claim 24, and further comprising predistorting the digital baseband I and Q signals fed to the I and Q circuits to aid in compensating for the amplitude, frequency and phase modulation errors.