Calibration systems for wireless electronic devices

1. A method of calibrating an electronic device having wireless communications circuitry with a calibration system, wherein the calibration system includes data acquisition equipment and calibration computing equipment and wherein the wireless communications circuitry comprises a calibration pattern generator and local oscillator, the method comprising:

with the wireless communications circuitry, transmitting an amplitude-modulated calibration signal to the data acquisition equipment;

with the data acquisition equipment, transferring the amplitude-modulated calibration signal to the calibration computing equipment;

with the calibration computing equipment, extracting a phase drift correction from the amplitude-modulated calibration signal;

with the calibration computing equipment, extracting pre-distortion coefficients from the amplitude-modulated calibration signal;

with the calibration pattern generator, generating a known amplitude-modulated calibration pattern;

with the local oscillator, generating a carrier signal; and

with the wireless communications circuitry, before transmitting the amplitude-modulated calibration signal to the data acquisition equipment, modulating the carrier signal with the known amplitude-modulated calibration pattern to create the amplitude-modulated calibration signal.

2. The method defined in claim 1 further comprising:

with the calibration computing equipment, applying the phase drift correction to the amplitude-modulated calibration signal.

3. The method defined in claim 2 wherein extracting the pre-distortion coefficients from the amplitude-modulated calibration signal comprises extracting the pre-distortion coefficients from the phase drift corrected amplitude-modulated calibration signal.

4. The method defined in claim 1 wherein the wireless communications circuitry comprises a power amplifier that amplifies the amplitude-modulated calibration signal prior to transmitting the amplitude-modulated calibration signal to the data acquisition equipment.

5. The method defined in claim 4 wherein the amplitude-modulated calibration signal is distorted by the power amplifier and wherein extracting the pre-distortion coefficients from the amplitude-modulated calibration signal comprises comparing the distorted amplitude-modulated calibration signal with the known amplitude-modulated calibration pattern.

6. The method defined in claim 5 wherein the wireless communications circuitry further comprises a pre-distortion compensator, and wherein the pre-distortion compensator is configured to alter a communications signal generated by the wireless communications circuitry using the pre-distortion coefficients.

7. The method defined in claim 1 further comprising, transmitting the pre-distortion coefficients to the electronic device.

8. The method defined in claim 7 further comprising storing the pre-distortion coefficients using the wireless communications circuitry.

9. The method defined in claim 1 wherein extracting the phase drift correction from the amplitude-modulated calibration signal comprises using a linear regression procedure to extract the phase drift correction.

10. A calibration system for wireless communications calibration of an electronic device, comprising:

data acquisition equipment having at least one local oscillator having a first frequency for receiving an amplifier-distorted amplitude-modulated calibration signal from the electronic device, wherein the electronic device comprises at least one local oscillator having a second frequency and wherein the first frequency has a drift with respect to the second frequency that causes a phase drift in the amplifier-distorted amplitude-modulated calibration signal; and

calibration computing equipment for extracting a phase drift correction from the amplifier-distorted amplitude-modulated calibration signal.

11. The calibration system defined in claim 10 wherein the electronic device further comprises a power amplifier, wherein the power amplifier induces amplifier distortion in the amplifier-distorted amplitude-modulated calibration signal, and wherein the calibration computing equipment is configured to apply the phase drift correction to the amplifier-distorted amplitude-modulated calibration signal.

12. The calibration system defined in claim 11 wherein the electronic device further comprises a pre-distortion compensator for pre-distorting an input signal to the power amplifier and wherein the calibration computing equipment is configured to extract pre-distortion coefficients from the phase drift corrected amplifier-distorted amplitude-modulated calibration signal.

13. The calibration system defined in claim 12 wherein the electronic device comprises a calibration pattern generator that generates a known amplitude-modulated calibration pattern, wherein extracting the pre-distortion coefficients from the phase drift corrected amplifier-distorted amplitude-modulated calibration signal comprises comparing the known amplitude-modulated calibration pattern with the phase drift corrected amplifier-distorted amplitude-modulated calibration signal.

14. The calibration system defined in claim 13 wherein the data acquisition equipment is coupled to the calibration computing equipment using a General Purpose Interface Bus cable and wherein the data acquisition equipment is configured to transfer amplifier-distorted amplitude-modulated calibration data to the calibration computing equipment using the General Purpose Interface Bus cable.

15. A method for obtaining pre-distortion coefficients for an electronic device having a power amplifier and a first oscillator that operates at a first frequency, the method comprising:

with the power amplifier, amplifying an amplitude-modulated calibration signal;

transmitting the amplified amplitude-modulated calibration signal to data acquisition equipment having a second oscillator that operates at a second frequency, wherein drift between the first and second frequencies causes bulk phase drift in the amplified amplitude-modulated calibration signal;

with calibration computing equipment, removing the bulk phase drift from the amplified amplitude-modulated calibration signal; and

with the calibration computing equipment, measuring an amplifier distortion in the amplified amplitude-modulated calibration signal.

16. The method defined in claim 15 further comprising:

with the data acquisition equipment, converting the amplified amplitude-modulated calibration signal into in-phase/quadrature-phase data samples; and

with the data acquisition equipment, transferring the in-phase/quadrature-phase data samples to the calibration computing equipment.

17. The method defined in claim 16 further comprising:

with the calibration computing equipment, using the measured amplifier distortion to obtain the pre-distortion coefficients.

18. The method defined in claim 17 wherein measuring the amplifier distortion comprises:

with the calibration computing equipment, comparing a received amplitude associated with the in-phase/quadrature-phase data samples to a known input amplitude; and

with the calibration computing equipment, comparing a received phase associated with the in-phase/quadrature-phase data samples to the known input amplitude.