l
BrHalf4W()
l
TCDiff()
6.1.2.1
Reverse
differential
Differential
measurements
have
the
advantage
of
an
input
reversal
option,
RevDiff
.
When
RevDiff
is
set
to
True,
two
differential
measurements
are
made,
the
first
with
a
positive
polarity
and
the
second
reversed.
Subtraction
of
opposite
polarity
measurements
cancels
some
offset
voltages
associated
with
the
measurement.
6.1.3
Improving
voltage
measurement
quality
The
following
topics
discuss
methods
of
generally
improving
voltage
measurements:
Read
More:
Consult
the
following
technical
papers
at
for
in-
depth
treatments
of
several
topics
addressing
voltage
measurement
quality:
l
Preventing and Attacking Measurement Noise Problems
l
Benefits of Input Reversal and Excitation Reversal for Voltage Measurements
l
Voltage Accuracy, Self-Calibration, and Ratiometric Measurements
6.1.3.1
Deciding
between
single-ended
or
differential
measurements
Deciding
whether
a
differential
or
single-ended
measurement
is
appropriate
is
usually,
by
far,
the
most
important
consideration
when
addressing
voltage
measurement
quality.
The
decision
requires
trade-offs
of
accuracy
and
precision,
noise
cancellation,
measurement
speed,
available
measurement
hardware,
and
fiscal
constraints.
In
broad
terms,
analog
ue
voltage
is
best
measured
differentially
because
these
measurements
include
the
following
noise
reduction
features
that
are
not
included
in
single-ended
measurements.
l
Passive Noise Rejection
o
No voltage reference offset
o
Common-mode noise rejection, which filters capacitively coupled noise
l
Active Noise Rejection
o
Input reversal
o
For more information, see
Compensating for offset voltage
Reasons for using single-ended measurements, however, include:
6. Measurements
48
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