How the Instrument Works
System Architecture
Summary
There is no such thing as the perfect probe, so you must use some discretion
in choosing the best type of probe for each measurement.
To make the correct choice, it's helpful to know the equivalent circuit of the
circuit under test. For truly demanding measurements, it may be worthwhile
to simulate the eect of the probe using SPICE. This discussion assumes a
simple resistance as the equivalent circuit for the circuit under test. For an
actual measurement, a more complete model is useful in evaluating the eects
of the
probe.
Some knowledge
of the
expected signal,
particularly
its
rise
time
or
spectral
content, is
also useful
in
making
a
probe
choice
.
Finally
,
it's
important
to
know
what
parameter
(voltage
or
time)
you
need
to measure
most accurately
,
because
some
tradeo
is
almost
always
required.
13-21
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