The purpose of this calibration is to determine the I/Q time skew adjustments required to minimize the I/Q time skew of internally generated signals on the I/Q External outputs. This adjustment will be required for a number of the unique I/Q baseband paths that exist from the baseband generator, through the instrument to the I/Q outputs.
The calibration is accomplished by applying identical multitone baseband signals to the I channel, the Q channel, but 180 degrees out of phase. The I/Q outputs are then summed together through a tee and the resultant waveform is measured with a spectrum analyzer. The I/Q time skew between the I and Q channels is then adjusted until the signals cancel each other to the maximum extent possible. This point of maximum cancellation will coincide with the point at which the I and Q channels I/Q time skew is minimized.
Test Equipment |
Preferred Model |
Alternate Model(s) |
Spectrum Analyzer |
E444xA1 |
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1.Select any model of PSA spectrum analyzer (E4440A, E4443A,E4445A, E4446A, E4447A, E4448A) that has a maximum frequency greater than or equal to the maximum frequency of the unit under test. An E4448A is required for units with Option 567. The E4448A frequency range is adequate for all PSG-D frequency configurations.
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Connect all test equipment as shown.
Connect GPIB cables to all GPIB-controlled test equipment.
While performing this adjustment, follow all instructions on the controller display.
Setup for I/Q Time Skew Baseband Calibration
If this adjustment fails, perform the following steps in order:
Check the equipment setup (see above). If the setup is incorrect, make the necessary corrections and rerun the adjustment.
If a 856xE/EC series spectrum analyzer is being used and the adjustment locks up, please check and ensure that the 856xE/EC's external reference is connected. The spectrum analyzer will lock up and not take a sweep when external reference is selected and there isn't one connected to it.
If this adjustment fails after step 1 and step 2, refer to the troubleshooting section of the signal generator's service guide. If you do not have a printed copy of the service guide (Option OBW), one is available either on the CD-ROM that came with your signal generator shipment or on the Keysight Website.
If you cannot correct the problem using the troubleshooting procedures in the Service Guide, obtain service from Keysight Technologies. Refer to Contacting Keysight Technologies.