HP 83480A User Manual

Increasing Measurement Accuracy
and Time-Interval Measurement
Time-Interval Measurements
You can extend this concept to channel-to-channel time-interval
measurements between edges of opposite polarity. Measuring the time
interval between two closely spaced edges of opposite polarity on two
channels is equivalent to measuring the width of a narrow pulse as shown in
Figure 9-8.
Figure
9-8.
Error
in
pulse
width
at
10%
level
is approximately
equal
to
the
error
in
10%{90%
rise
time.
Probe
capacitive
loading
The
capacitance
of
the
probe
tip
to
ground forms
an
RC
circuit
with
the
output
resistance
of
the
circuit
under
test.
The
time
constant
of
this
RC
circuit
will
slow
the
rise
time
of
any
transitions
,
increase
the
slew
rate
,
and
introduce
delay
in
the
actual
time
of
transitions
.
The
approximate
rise
time
of
a
simple
RC
circuit
is
2.2RC.
Thus
,
for
an
output
resistance
of
100 W
and a
probe
tip
capacitance
of
8
pF
,
the
real
rise
time
at
the
node under
test cannot
be faster than approximately 1.8 ns. Without the probe, the rise time might
be faster.
9-18

HP 83480A Specifications

General

Brand	HP
Model	83480A
Category	Measuring Instruments
Language	English