Measurement Principles
R&S
®
RT-ZPR20
R&S
®
RT-ZPR40
26
User Manual 1800.5035.02 ─ 03
5.2
Frequency Response
The R&S
RT-ZPR20/40 probe is a dedicated power rail probe, designed for mea-
surements at low impedance voltage sources such as DC power supplies with an
output impedance <
1
Ohm.
A DUT with an output impedance (R
S
) higher than 1
Ohm leads to a mismatch
between DC gain and AC gain. The mismatch causes a step at 1
MHz and thus
non-flat frequency response.
In the time domain, a non-ideal frequency response occurs as a step which only
gradually approaches the final DC value.
Figure 5-3: Example of the frequency response of the R&S
RT-ZPR40 probe with SMA
extension cable for different source impedances
Frequency Response
