Oscilloscope Bandwidth Tutorial
B
4000 X-Series Oscilloscopes Advanced Training Guide
165
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 Keysight’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 108
100 MHz digital clock signal captured on a 1 GHz bandwidth scope
