Tektronix WFM 601A, WFM 601E, WFM 601M - page 81

Reference
WFM 601A, WFM 601E & WFM 601M User Manual 3–25
Calculating Actual Rise Time. The waveform monitor Eye display has a bandwidth
of 450 MHz which equates to a 20 – 80% rise time of 500 ps. Consider this finite
rise time when you measure the displayed rise time. You can calculate the actual
rise time of the source being measured using the following formula:
Ǹ(TR(measured))2–(0.5ns)2
TR(source) =
TR(source) = the actual 20 – 80% rise time of the source (in ns);
TR(measured) = the 20 – 80% rise time measured on the waveform monitor (in ns)
Table 3–1 lists actual rise times for a number of rise time values measured with
the waveform monitor.
Table 3–1: List of measured and actual rise times for the
waveform monitor
20–80% rise time measured Actual 20–80% rise time
640 ps 400 ps
710 ps 500 ps
780 ps 600 ps
860 ps 700 ps
900 ps 750 ps
940 ps 800 ps
1.0 ns 900 ps
1.1 ns 1.0 ns
1.2 ns 1.1 ns
1.3 ns 1.2 ns
1.4 ns 1.3 ns
1.5 ns 1.4 ns
1.6 ns 1.5 ns