15.2.3
High accuracy passive, single
-
ended isolated voltage probes
High accuracy passive, single
-
ended isolated voltage probes divide an isolated
input signal by a specific factor. They are designed in an “isolated way" so that
they can be used in series with an isolated unbalanced amplifier. They are
called “isolated voltage probes”, although the amplifier and not the probe adds
the isolation.
10 * Udiff
Uiso
Uiso
Udiff
(+)
(-)
(-)
GND
High voltage
probe
GND
Single-ended isolated or
unbalanced differential amplifier
900K
1
10k
900K
Isolation
Barrier
100K
(+)
(+)
(-)
Uiso
Non-isolated
system
Figure 15.9:
Typical example of a high accuracy voltage probe for isolated
amplifiers – as external divider
High accuracy passive, single
-
ended isolated voltage probes are designed to
overcome the accuracy loss that comes with the use of passive, single
-
ended
isolated voltage probes. To achieve this, they form a complete, high accuracy
voltage divider in series and parallel with the amplifier input. The accuracy is
therefore mainly by the probe itself and maintained at a high level. There is still
a capacitive component in this divider, so the amplifier and the probe need to
match. Only a specific combination of probe and amplifier can maintain high
overall accuracy using the full pass band of the amplifier and probe. However,
as the division only applies to the positive side of the amplifier input, the input
range is increased while the isolation voltage remains the same as without a
probe. These probes can only be used in series with isolated unbalanced
amplifiers. These probes overcome the problems of “standard” passive probes
and offer increased input ranges AND high accuracy.
GEN3i
352
I3763-3.1 en HBM: public
