N5161A/62A/81A/82A/83A MXG Signal Generators User's Guide

Basic Digital Operation—No BBG Option InstalledI/Q ModulationI/Q ModulationThe following factors contribute to the error vector magnitude:• Differences in amplitude, phase, and delay between the I and Q channels• DC offsetsThe I/Q menu provides adjustments to compensate for some of the differences in the I and Q signalsor to add impairments.See also “Modulating the Carrier Signal” on page 61.Figure 7-1I/Q Display and SoftkeysThis panel displays the externalI/Q signal routing.This panel displays the current status and settingsof the I/Q adjustments. Grey text indicates I/Qadjustments are off.Sets the dc offsetFor details on each key, use key helpas described on page 42.The following table shows common uses for the adjustments.Table 7-1 I/Q Adjustments UsesI/Q Adjustment Effect ImpairmentOffset Carrier Feedthrough dc offsetOffsets the phase of the Q signal relative to the phase of theI signal. The quadrature adjustment key is in units ofdegrees. This adjustment is not calibrated.Quadrature AngleEVM errorI/Q Imagesphase skewI/Q path delay136 Agilent N5161A/62A/81A/82A/83A MXG Signal Generators User’s Guide