5968-4632E Datasheet, PDF (74/77 Pages) Keysight Technologies – Probing Solutions for Logic Analyzers

74 | Keysight | Probing Solutions for Logic Analyzers - Data Sheet
Probing Solutions for 40-pin Logic Analyzers
Custom Probing (Continued)
Notes on using discrete
components
Discrete components can be used to
design the isolation network. Keysight
recommends the circuit shown in Figure
9.42. To achieve the equivalent load
shown in the figure, trace lengths should
be minimized by locating the RC network
very near the measured node. Actual
load will be the stub length load added
to the equivalent load in the figure. Trace
length from the suggested on-board RC
network to the target connector must be
3 to 4 inches or less. This transmission
line should be designed for an impedance
in the range of 80 to 100 ohms (closer to
100 ohms is better).
Suggested on board isolation network
k
8.2 pF
Equivalent load
7.4 pF
Includes on board isolation network
and logic analyzer
Figure 9.41. Equivalent load for on-target discrete components.