Filter
Top Products
Reference
80E00 Electrical Sampling Modules User Manual
19
propagation time from the acquisition point to the short in the device under test
and back. See Figure 8.
250 mV
0V
E
i
E
r
Figure 8: St ep generator with a shorted output
Operation Into a 50 Ω Load. Initially, the diode switch is conducting --10 mA.
Since the step-generator output is connected to a 50 Ω load, the resistance to
ground at the acquisition point is 25 Ω (because of the internal 50 Ω impedance).
+250 mV
0V
E
i
E
r
Figure 9: St ep generation with a 50 Ω load
When the diode switch opens (reverse-biased), apparent resistance to ground at
the acquisition point (and at the channel connector) is 25 Ω because the internal
termination resistance is 50 Ω in parallel with the connector impedance of 50 Ω.
The voltage at the acquisition point rises to +250 mV.
The transition propagates to the 50 Ω load and no reflection occurs.
Operation Into an Open. Initially, the diode switch is conducting --10 mA. Since
the step-generator output is open, the resistance to ground at the acquisition point
is 50 Ω (because of the internal 50 Ω impedance).
+250 mV
0V
+500 mV
E
i
E
r
Figure 10: St ep generation with an open circuit