Keysight Technologies N2750A, User Manual

Page: 33 / 76

SPICE Models
2
N2750/1/2A User’s Guide 33
N2750A probe with the N2777A Solder-In Tip
The following SPICE RLC circuit models the input impedance of the N2750A and
N2777A combination. Observe the following items when positioning the tip wires:
• It is assumed that the tip wires are approximately parallel and connected to the
target at approximately 100 mils spacing.
• As shown in Figure 15 , the tip wires are assumed to be kept roughly parallel
from the N2750A probe to the solder-in point. Dramatically spreading the tip
wires to cover a large span, significantly alters the input model and a new
model would be needed.
• Pin 1 is the + input, pin 2 is the – input and pin 3 is the ground connection.
• The impedance is
not a strong function of the orientation of the tip wires (for
example, vertical or flat) as long as, when flat, the tip wires are not positioned
down on the ground plane surface.
Figure 15 Nominal Connections
NOTE Do not infer any transfer function accuracy from this model.