User Manual

Characteristics of Differential Probes
R&S
®
RT-ZHD07/15/16/60
28User Manual 1800.2588.02 ─ 01
3 Characteristics of Differential Probes
A differential probe has three sockets: the positive signal socket (+), the negative sig-
nal socket (-), and the signal output which is connected to ground.
Figure 3-1: Input voltages on a differential probe
Multiple input voltages can be defined for a differential probe:
●
Differential mode input voltage (V
in
, V
dm
)
Voltage between the positive and negative signal sockets
●
Positive single-ended input voltage (V
p
)
Voltage between the positive signal socket and the ground socket
●
Negative single-ended input voltage (V
n
)
Voltage between the negative signal socket and the ground socket
●
Common mode input voltage (V
cm
)
Mean voltage of positive and negative signal sockets referred to the ground socket,
respectively
Two of these voltages are independent values, the other two can be calculated:
2
np
cm
npin
VV
V
VVV



Typically, the differential and the common mode input voltages are used to describe
the behavior of a differential probe.
The output voltage V
out
, which is displayed on the base unit, is obtained by superim-
posing the voltages generated from the differential mode input voltage and from the
common mode input voltage:
cmvcminvdmout
VAVAV 