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®
R&S
RT-ZS60
Fig. 4-9: Signal loading caused by the R&S RT-ZS60 probe at an effective source impe-
dance of 25 Ω
4.2.1.1
Input Resistance R
The input resistance determines the loading of the DUT at DC and very low fre-
quencies (< 4 kHz). A low input resistance can potentially disturb measurements
of high-frequency signals as it influences the DC operating point of active compo-
nents. This effect is negligible for the majority of applications involving the
R&S RT-ZS60 probe due to the very high input resistance of the probe (1 MΩ).
4.2.1.2
LF Capacitance C
The LF capacitance causes the input impedance to decrease in the low frequency
range (4 kHz to 20 MHz). The LF capacitance affects the settling time of the loa-
ded input voltage in the case of fast transients, see
User Manual 1418.7342.02 ─ 03
in
LF
Measurement Principles
Signal Loading of the Input Signal
figure
4-9.
37
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