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176 Chapter 8
Multitone Waveform Generator
Creating, Viewing, and Optimizing Multitone Waveforms
4. Press Q Offset and turn the rotary knob to further reduce the carrier feedthrough level.
5. Repeat steps 3 and 4 until you have reached the lowest possible carrier feedthrough level.
6. On the spectrum analyzer, return the resolution bandwidth to its previous setting.
7. Turn on waveform averaging.
8. Create a marker and place it on the peak of one of the end tones.
9. Create a delta marker and place it on the peak of the adjacent intermodulation product, which should be
spaced 10 MHz from the marked tone.
10. Measure the power difference between the tone and its distortion product.
You should now see a display that is similar to the one shown in Figure 8-6 on page 176. Your optimized
multitone signal can now be used to measure the IMD products generated by a device-under-test.
Note that carrier feedthrough changes with time and temperature. Therefore, you will need to periodically
readjust your I and Q offsets to keep the signal optimized.
Figure 8-6
Minimized
Carrier
Feedthrough
Intermodulation
Distortion
Tone 1
Carrier
Feedthrough
Distortion
Tone 10