Keysight Technologies InfiniiMax III Series User Manual page 19

SPICE Models for N5440A, N5447A, N5441A, N5445A, and N5444A Probe Heads
Figure 8 SPICE circuit to use for N5440A, N5447A, N5441A, N5445A, and
N5444A probe heads
The input impedance is only a function of the probe head; the amplifier
input does not significantly affect the input impedance.
1. Using InfiniiMax III Series Probes
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