Keysight EXG and MXG X-Series Signal Generators User’s Guide 415Multitone and Two-Tone Waveforms (Option 430)Using Two–Tone Modulation7. Set the attenuation to 4 dB, so you’re not overdriving the input mixer on the spectrumanalyzer.You should now see a two–tone waveform with a 6 GHz center carrier frequency that is similar tothe one shown in Figure 17-2 on page 415. You will also see IMD products at 10 MHz intervalsabove and below the generated tones, and a carrier feedthrough spike at the center frequency withcarrier feedthrough distortion products at 10 MHz intervals above and below the center carrierfrequency.Figure 17-2Minimizing Carrier FeedthroughThis procedure describes how to minimize carrier feedthrough and measure the difference in powerbetween the tones and their intermodulation distortion products. Before beginning this procedure,it is important that a recent I/Q calibration has been performed on the instrument. The procedurefor performing an I/Q calibration (refer to “I/Q Calibration” on page 250).This procedure builds upon the previous procedure.1. On the spectrum analyzer, set the resolution bandwidth for a sweep rate of about100 to 200 ms. This will allow you to dynamically view the carrier feedthrough spike as youmake adjustments.2. On the signal generator, press I/Q > I/Q Adjustments > I/Q Adjustments Off On to On.3. Press Internal Baseband Adjustments > I Offset and turn the rotary knob while observing thecarrier feedthrough with the spectrum analyzer. Changing the I offset in the proper directionwill reduce the feedthrough level. Adjust the level as low as possible.4. Press Q Offset and turn the rotary knob to further reduce the carrier feedthrough level.IntermodulationDistortionTwo–ToneChannelsCarrier FeedthroughDistortionCarrierFeedthroughFor details on each key, use key help as described on page 40.
