HP 83480A - Probe Loading

How the Instrument Works
System Architecture
Suppose you are trying to debug an intermittent failure in a state machine
that is implemented in high-speed CMOS logic. You know you need a
high-performance digitizing analyzer, but you don't know which probe gives
the best results.
There are two major factors inuencing probe selection:
1. the load the probe imposes on the circuit
2. the required bandwidth of the circuit with the probe
Probe loading Figure 13-7 shows a simplied diagram of the circuit with the probe attached
to indicate the principal loading eects. The probe load has both resistive
and
capacitive
components
.
In
addition
to
this
,
the
inductance in
the probe
ground
lead
can
cause
ringing.
Figure 13-7. Simplied equivalent circuit of DUT and probe.
13-13