4349B
A
dditional
Error
Due
to
V
oltage
Source
Noise
The
error
caused
by
the
DC
voltage
source's
noise
appears
as a
measurement value
uctuation.
Figure
6-5
shows
an
estimation
of
the additional
error caused
by the
DC voltage
source's noise
under
the
following
conditions:
External
DC
voltage
output
:
100
V
4349B
Measurement
Speed
:
30
ms
DC
voltage
source
performance
:
Ripple
5
Vrms(@50
Hz)
Wide
band
nosie
1
Vrms/
p
H
z
(@50
Hz)
Switching
noise
<
10
mVrms(@100
Hz)
Note
The
DC
voltage
source's
output resistance
is assumed
to be
0
in
this
example
.
Figure 6-5. A
dditional Error Due to V
oltage Source Noise
For example
, when measuring a capacitor of 2 G resistance and 1
F capacitance
, the leakage
current (50 nA=100 V/2 G) can be measured within 10% additional error
. That is
, the
measurement value will uctuate from 45 nA to 55 nA (or 1.82 G to 2.22 G).
Figure 6-5 shows the measurement error due to the external DC voltage source only
.T
o
estimate the total system measurement error, it is also necessary to include the 4349B's
measurement accuracy in addition to the error shown in Figure 6-5.
6-10 Application Measurement
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