Vertical Setups Termination Controls
TekProbe/TekVPI Interface
This interface enables the instrument to sense information about the probe such as the serial number
and other unique identification information. It also allows the instrument to provide power directly to
the probe.
With this information, the instrument can automatically set up its requirements to match the
characteristics of the probe, such as termination and attenuation.
High Impedance Probes
Most general-purpose probes have high input impedance.
The high input resistance of passive probe s (typically 10 MΩ) provides negligible DC loading and
provides accurate DC amplitude measurements.
Most passive 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 high resistance passive probes for measurements involving the following:
Device characterization (above 15 V, thermal drift applications)
Maxim
um amplitude sensitivity using 1X probe
Large voltage range (between 15 V and 500 V)
Qualitative or go/no-go measurements
Active Probes
Active voltage probes often contain preamplifiers that provide high resistance and low capacitance at
the probe tip. Some active voltage probes contain differential amplifiers that provide high Common
Mode Rejection Ratio (CMRR).
Active current probes often contain Hall-effect sensors that extend the probe bandwidth down to DC.
Many active probes, especially high frequency probes, can drive a 50 Ω instrument input.
DSA/DPO70000D, MSO/DPO/DSA70000C, DPO7000C, and MSO/DPO5000 Series 491
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