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3000 X-Series Oscilloscopes Advanced Training Guide
B
Oscilloscope Bandwidth Tutorial
This tutorial on oscilloscope bandwidth focused on oscilloscopes that
exhibit a Gaussian frequency response, which is typical of scopes that
have bandwidth specifications of 1 GHz and below. Many higher bandwidth
oscilloscopes exhibit a frequency response that has a sharper roll- off
characteristic. With this type of frequency response, in- band frequencies
(frequencies below the - 3 dB frequency) are attenuated less, while
out- of- band frequencies (frequencies above the - 3 dB frequency) are
suppressed to a higher degree. This type of frequency response, which
begins to approximate an ideal “brick- wall” filter, is sometimes called a
“maximally- flat” frequency response. The formulas for computing required
oscilloscope bandwidth on these higher bandwidth scopes (> 1 GHz) are
different than what was presented in this tutorial guide. If you would like
to learn more about oscilloscope bandwidth, you can download Agilent’s
application note title, “
Evaluating Oscilloscope Bandwidths for your
Application
”. This publication is listed in the “Related Literature” section
of this document with instructions on how to download.
1
High-Speed Digital Design, A Handbook of Black Magic, Howard Johnson, Martin Graham, 1993, Prentice
Hall PTD, Prentice-Hall, Inc, Upper Saddle River, New Jersey 07458
Figure 89 100 MHz digital clock signal captured on a 1 GHz bandwidth scope