Agilent Technologies E8247C, Руководство пользователя

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Chapter 5 113
Dual Arbitrary Waveform Generator
Using Waveform Clipping
Waveform Clipping Concepts
Waveforms with high power peaks can cause intermodulation distortion, which generates spectral regrowth
(a condition that interferes with signals in adjacent frequency bands). The clipping function allows you to
reduce high power peaks.
The clipping feature is available only with the Dual Arb mode.
How Power Peaks Develop
To understand how clipping reduces high power peaks, it is important to know how the peaks develop as the
signal is constructed. I/Q waveforms can be the summation of multiple channels (see
Figure 5-11 ).
Whenever most or all of the individual channel waveforms simultaneously contain a bit in the same state
(high or low), an unusually high power peak (negative or positive) occurs in the summed waveform. This
does not happen frequently because the high and low states of the bits on these channel waveforms are
random, which causes a cancelling effect.
Figure 5-11 Multiple Channel Summing
The I and Q waveforms combine in the I/Q modulator to create an RF waveform. The magnitude of the RF
envelope is determined by the equation , where the squaring of I and Q always results in a positive
value.