Calibrating automatic test equipment to account for magnitude and phase offsets

1. A method of calibrating automatic test equipment (ATE) comprising transmission paths that transport signals, the method comprising:

obtaining amplitude gains of the signals across the transmission paths;

obtaining phase delays of the signals across the transmission paths;

obtaining magnitude and phase offsets associated with the signals based on the amplitude gains and the phase delays; and

calibrating the ATE using the magnitude and phase offsets;

wherein the transmission paths comprise an inphase (I) transmission path and a quadrature (Q) transmission path; and

wherein the amplitude gains comprise a Gain_II gain across the I transmission path, a Gain_QQ gain across the Q transmission path, and gains across connections of the I and Q transmission paths wherein the gains across the connections of the I and Q transmission paths comprises a Gain_IQ gain from the I transmission path to the Q transmission path, and a Gain_QI gain from the Q transmission path to the I transmission path.

2. The method of claim 1 , wherein the amplitude gains comprise positive or negative deviations from initial values of the signals.

3. The method of claim 1 , wherein the phase delays comprise a Phase_II phase delay across the I transmission path, a Phase_QQ phase delay across the Q transmission path, and phase delays across connections of the I and Q transmission paths.

4. The method of claim 3 , wherein the phase delays across the connections of the I and Q transmission paths comprises a Phase_IQ phase delay from the I transmission path to the Q transmission path, and a Phase_QI phase delay from the Q transmission path to the I transmission path.

5. The method of claim 4 , wherein the ATE comprises a source path and a capture path, the source path to provide signals to a device under test (DUT) and the capture path to receive signals from the DUT;

wherein obtaining the magnitude and phase offsets comprises calculating a source-path magnitude offset and a source-path phase offset for the source path, and calculating a capture-path magnitude offset and a capture-path phase offset for the capture path; and

wherein calibrating comprises calibrating the source path using the source-path magnitude offset and the source-path phase offset, and calibrating the capture path using the capture-path magnitude offset and the capture-path phase offset.

6. The method of claim 5 , wherein the source-path magnitude offset is calculated as follows: Gain_II-Gain_QI;

wherein the source-path phase offset is calculated as follows:

Phase_II-Phase QI;

wherein the capture-path magnitude offset is calculated as follows:

Gain_II-Gain_IQ; and

wherein the capture-path phase offset is calculated as follows: Phase_II-PhaseIQ.

7. The method of claim 5 , wherein the source-path magnitude offset is calculated as follows: Gain_IQ-Gain_QQ;

wherein the source-path phase offset is calculated as follows:

Phase_IQ-Phase QQ;

wherein the capture-path magnitude offset is calculated as follows:

Gain_QI-Gain_QQ; and

wherein the capture-path phase offset is calculated as follows:

Phase_QI-PhaseQQ.

8. A machine-readable medium that stores executable instructions to calibrate automatic test equipment (ATE) having transmission paths, the instructions to cause one or more machines to:

obtain amplitude gains of the signals across the transmission paths;

obtain phase delays of the signals across the transmission paths;

obtain magnitude and phase offsets associated with the signals based on the amplitude gains and the phase delays; and

calibrate the ATE using the magnitude and phase offsets;

wherein the transmission paths comprise an inphase (I) transmission path and a quadrature (Q) transmission path; and

wherein the amplitude gains comprise a Gain_II gain across the I transmission path, a Gain_QQ gain across the Q transmission path, and gains across connections of the I and Q transmission paths wherein the gains across the connections of the I and Q transmission paths comprises a Gain_IQ gain from the I transmission path to the Q transmission path, and a Gain_QI gain from the Q transmission path to the transmission path.

9. The machine-readable medium of claim 8 , wherein the amplitude gains comprise positive or negative deviations from initial values of the signals.

10. The machine-readable medium of claim 8 , wherein the phase delays comprise a Phase_II phase delay across the I transmission path, a Phase_QQ phase delay across the Q transmission path, and phase delays across connections of the I and Q transmission paths.

11. The machine-readable medium of claim 10 , wherein the phase delays across the connections of the I and Q transmission paths comprises a Phase_IQ phase delay from the I transmission path to the Q transmission path, and a Phase_QI phase delay from the Q transmission path to the I transmission path.

12. The machine-readable medium of claim 11 , wherein the ATE comprises a source path and a capture path, the source path to provide signals to a device under test (DUT) and the capture path to receive signals from the DUT;

wherein obtaining the magnitude and phase offsets comprises calculating a source-path magnitude offset and a source-path phase offset for the source path, and calculating a capture-path magnitude offset and a capture-path phase offset for the capture path; and

wherein calibrating comprises calibrating the source path using the source-path magnitude offset and the source-path phase offset, and calibrating the capture path using the capture-path magnitude offset and the capture-path phase offset.

13. The machine-readable medium of claim 12 , wherein the source-path magnitude offset is calculated as follows: Gain_II-Gain_QI;

wherein the source-path phase offset is calculated as follows:

Phase_II-Phase QI;

wherein the capture-path magnitude offset is calculated as follows:

Gain_II-Gain_IQ; and

wherein the capture-path phase offset is calculated as follows: Phase_II-PhaseIQ.

14. The machine-readable medium of claim 12 , wherein the source-path magnitude offset is calculated as follows: Gain_IQ-Gain_QQ;

wherein the source-path phase offset is calculated as follows:

Phase_IQ-Phase QQ;

wherein the capture-path magnitude offset is calculated as follows:

Gain_QI-Gain_QQ; and

wherein the capture-path phase offset is calculated as follows:

Phase_QI-PhaseQQ.

15. Automatic test equipment (ATE) comprising:

inphase transmission paths; and

quadrature transmission paths, the inphase transmission paths and the quadrature transmission paths transmitting signals that are 90° out of phase; and

a processing device to:

obtain amplitude gains of signals across the inphase transmission paths and across the quadrature transmission paths;

obtain phase delays of signals across the inphase transmission paths and across the quadrature transmission paths;

obtain magnitude and phase offsets associated with the signals based on the amplitude gains and the phase delays; and

calibrate the ATE using the magnitude and phase offsets;

wherein the amplitude gains comprise a Gain_II gain across an inphase transmission path, a Gain_QQ gain across a quadrature transmission path, and gains across connections of the inphase and quadrature transmission paths wherein the gains across the connections of the Inphase and Quadrature transmission paths comprises a Gain_IQ gain from the Inphase transmission path to the Quadrature transmission path, and a Gain_QI gain from the Quadrature transmission path to the Inphase transmission path.

16. The ATE of claim 15 , comprising:

a source path to transmit signals to a device under test (DUT); and

a capture path to receive signals from the DUT;

wherein separate magnitude and phase offsets are obtained for the source path and the capture path; and

wherein calibrating comprises calibrating both the source path and the capture path using the separate magnitude and phase offsets.