Oscilloscope Reference High
High
The high level measurement is the value u sed as 100% whenever high reference, mid reference, or low
reference values are needed, such as in fall time or rise time measurements. This value can be calculated
using either
the min/max or histogram method. The min/max method uses the maximum value found. The
histogram method uses the most common value found above the midpoint. This value is measured over
the entire waveform or g ated region.
High impedance probes
Most general-purpose probes have high input impedance.
The high i
nput resistance of passive probes (typically 10 MΩ) provides negligible DC loading and
provides accurate DC amplitude measurements.
Most pas
sive probes require the instrument input impedance to be 1 MΩ. However, their 8 pF to
12 pF (over 60 pF for 1X) capacitive loading can distort timing and phase measurements.
Use hig
h resistance passive probes for measurements involving the following:
Device characterization (above 15 V, thermal drift applications)
Maximum amplitude sensitivity using 1X p robe
Largevoltagerange(between15Vand500V)
Qualitative or go/no-go measurements
DSA/DPO70000D, MSO/DPO/DSA70000C, DPO7000C, and MSO/DPO5000 Series 825