Apparatus and method for calibration of gain and/or phase imbalance and/or DC offset in a communication system

1. A radio frequency (RF) transmitter system for communication, the transmitter system comprising:

a transmit pre-distortion module including a first transmit input configured to receive a first transmit calibration signal during a transmit calibration mode and configured to receive a first transmit communication signal during a transmit communication operation mode, the transmit pre-distortion module further including a second transmit input configured to receive one or more transmit calibration adjustment signals to adjust the first transmit calibration signal during the transmit calibration mode and configured to receive one or more transmit calibration adjustment signals to adjust the first transmit communication signal during the transmit communication operation mode, the transmit pre-distortion module further including a first transmit output configured to provide a second transmit calibration signal during the transmit calibration mode and configured to provide a second transmit communication signal during the transmit communication operation mode;

a transmit channel frequency converter coupled to the transmit pre-distortion module, the transmit channel frequency converter including a third transmit input configured to receive a third transmit calibration signal during the transmit calibration mode and configured to receive a third transmit communication signal during the transmit communication operation mode, the transmit channel frequency converter further including a fourth transmit input configured to receive a transmit reference signal, the transmit channel frequency converter further including a second transmit output configured to provide a fourth transmit calibration signal during the transmit calibration mode and configured to provide a fourth transmit communication signal during the transmit communication operation mode, the fourth transmit calibration signal comprising a frequency-translated version of the third transmit calibration signal, the fourth transmit communication signal comprising a frequency-translated version of the third transmit communication signal; and

a transmit calibration module coupled to the transmit channel frequency converter and the transmit pre-distortion module, the transmit calibration module including a calibration signal generator for generating a calibration signal, the transmit calibration module further including a fifth transmit input configured to receive a fifth transmit calibration signal during the transmit calibration mode, the transmit calibration module further including a third transmit output configured to provide the one or more transmit calibration adjustment signals for the first transmit calibration signal and the one or more transmit calibration adjustment signals for the first transmit communication signal, the transmit calibration module further including a fourth transmit output configured to provide a sixth transmit calibration signal from the calibration signal generator during the transmit calibration mode, wherein value or values of the one or more transmit calibration adjustment signals for the first transmit calibration signal are determined during the transmit calibration mode, and value or values of the one or more transmit calibration adjustment signals for the first transmit communication signal are determined during the transmit calibration mode.

2. An RF transmitter system of claim 1 , wherein the transmit calibration module includes a plurality of filters configured to separate and provide a first calibration error signal associated with a transmit calibration signal and a second calibration error signal associated with the transmit calibration signal, wherein the first and second calibration error signals are not based on any transmit communication signal.

3. An RF transmitter system of claim 2 , wherein the first calibration error signal corresponds to an error due to gain and/or phase imbalance, and the second calibration error signal corresponds to an error due to DC offset.

4. An RF transmitter system of claim 1 , wherein the transmit calibration module includes a detector, a calibration receiver, a calibration processor and a microprocessor.

5. An RF transmitter system of claim 4 , wherein the calibration receiver includes one or more analog-to-digital converters, a plurality of bandpass filters and a plurality of detectors.

6. An RF transmitter system of claim 4 , wherein the calibration processor includes one or more memories, a calibration controller, a look-up table and a calibration signal generator.

7. An RF transmitter system of claim 1 , wherein the transmit pre-distortion module includes a plurality of multipliers and a plurality of adders.

8. An RF transmitter system of claim 1 , wherein the first transmit input of the transmit pre-distortion module is coupled to the calibration signal generator of the transmit calibration module, wherein the sixth transmit calibration signal from the calibration signal generator is the first transmit calibration signal.

9. An RF transmitter system of claim 1 , wherein each of the first transmit input and the third transmit input includes an in-phase input and a quadrature-phase input,

wherein each of the first transmit output and the fourth transmit output includes an in-phase output and a quadrature-phase output.

10. A radio frequency (RF) transmitter system for communication, the transmitter system comprising:

a transmit pre-distortion module including a first transmit input configured to receive a first transmit calibration signal during a transmit calibration mode and configured to receive a first transmit communication signal during a transmit communication operation mode, the transmit pre-distortion module further including a second transmit input configured to receive one or more transmit calibration adjustment signals to adjust the first transmit calibration signal during the transmit calibration mode and configured to receive one or more transmit calibration adjustment signals to adjust the first transmit communication signal during the transmit communication operation mode, the transmit pre-distortion module further including a first transmit output configured to provide a second transmit calibration signal during the transmit calibration mode and configured to provide a second transmit communication signal during the transmit communication operation mode, the one or more transmit calibration adjustment signals comprising an offset parameter associated with DC offset and an imbalance parameter associated with at least one of gain and phase imbalances;

a transmit channel frequency converter coupled to the transmit pre-distortion module, the transmit channel frequency converter including a third transmit input configured to receive a third transmit calibration signal during the transmit calibration mode and configured to receive a third transmit communication signal during the transmit communication operation mode, the transmit channel frequency converter further including a second transmit output configured to provide a fourth transmit calibration signal during the transmit calibration mode based on the third transmit calibration signal and a transmit reference signal and configured to provide a fourth transmit communication signal during the transmit communication operation mode, the fourth transmit calibration signal comprising a frequency-translated version of the third transmit calibration signal, the fourth transmit communication signal comprising a frequency-translated version of the third transmit communication signal; and

a transmit calibration module coupled to the transmit channel frequency converter and the transmit pre-distortion module, the transmit calibration module further including a fifth transmit input configured to receive a fifth transmit calibration signal during the transmit calibration mode, the transmit calibration module further including a third transmit output configured to provide the one or more transmit calibration adjustment signals for the first transmit calibration signal and the one or more transmit calibration adjustment signals for the first transmit communication signal, wherein value or values of the one or more transmit calibration adjustment signals for the first transmit calibration signal are determined during the transmit calibration mode, and value or values of the one or more transmit calibration adjustment signals for the first transmit communication signal are determined during the transmit calibration mode.

11. An RF transmitter system of claim 10 ,

wherein the transmit channel frequency converter further includes a fourth transmit input configured to receive the transmit reference signal,

wherein the transmit calibration module includes a calibration signal generator for generating a calibration signal, and

wherein the transmit calibration module further includes a fourth transmit output configured to provide a sixth transmit calibration signal from the calibration signal generator during the transmit calibration mode.

12. An RF transmitter system of claim 10 , wherein the transmit calibration module includes a plurality of filters configured to separate and provide a first calibration error signal associated with a transmit calibration signal and a second calibration error signal associated with the transmit calibration signal, wherein the first and second calibration error signals are not based on any transmit communication signal.

13. An RF transmitter system of claim 12 , wherein the first calibration error signal corresponds to an error due to gain and/or phase imbalance, and the second calibration error signal corresponds to an error due to DC offset.

14. An RF transmitter system of claim 10 , wherein the transmit calibration module includes a detector, a calibration receiver, a calibration processor and a microprocessor.

15. An RF transmitter system of claim 14 , wherein the calibration receiver includes one or more analog-to-digital converters, a plurality of bandpass filters and a plurality of detectors, and

wherein the transmit pre-distortion module includes a plurality of multipliers and a plurality of adders.

16. An RF transmitter system of claim 14 , wherein the calibration processor includes one or more memories, a calibration controller, a look-up table and a calibration signal generator.

17. An RF transmitter system of claim 11 , wherein the first transmit input of the transmit pre-distortion module is coupled to the calibration signal generator of the transmit calibration module, wherein the sixth transmit calibration signal from the calibration signal generator is the first transmit calibration signal.

18. An RF transmitter system of claim 11 , wherein each of the first transmit input and the third transmit input includes an in-phase input and a quadrature-phase input, wherein each of the first transmit output and the fourth transmit output includes an in-phase output and a quadrature-phase output.