Measurement Principles
R&S
®
RT-ZS60
37
User Manual 1418.7342.02 ─ 01
Fig. 4-9: Signal loading caused by the R&S
RT-ZS60 probe at an effective source impedance
of 25 Ω
4.3.1.1
Input Resistance R
in
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 components.
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).
4.3.1.2
LF Capacitance C
LF
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 loaded
input voltage in the case of fast transients, see
.
Signal Loading of the Input Signal
