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A40B
Instruction Manual
The AC-DC difference of the UUT shunt in ppm is determined from:
Where:
δ
δ
δ
δ
V
V
V
V
η
η
Current Source DC Noise
From some transconductance amplifiers, noise on DC can be problematic. The
Fluke Calibration system addresses this problem by triggering the two
nanovoltmeters at the same time so they integrate simultaneously to maximize
noise immunity.
UUT DC Resistance Measurement
The DC resistance of the UUT is determined by Ratio measurement against the
Reference Standard shunt. See Figure 7. The TVC assemblies are disconnected
and the outputs of the Reference Standard and UUT shunts are each connected
to the second input of their nanovoltmeter. DC reversal is employed to minimize
thermal emf and DC zero offset errors.
30
(
V
δ
δ
=
+
ACSTD
UUT
STD
η
STD
= AC-DC Difference of UUT in ppm
UUT
= AC-DC Difference of UUT SJTVC at the test frequency in ppm
UUT:TVC
= AC-DC Difference of reference Shunt in ppm
STD
= AC-DC Difference of STD SJTVC at the test frequency in ppm
STD:TVC
= Reference shunt voltage with AC current
ACSTD
= Reference shunt voltage, average of forward and reverse DC current
DCSTD
= UUT shunt voltage with AC current
ACUUT
= UUT shunt voltage, average of forward and reverse DC current
DCUUT
= Gain sensitivity of the UUT measurement system
UUT
= Gain sensitivity of the Reference Standard measurement system
STD
6
−
V
* )
10
(
V
−
DCSTD
ACUUT
η
×
V
DCSTD
UUT
6
−
V
* )
10
δ
+
DCUUT
USTD
:
TVC
×
V
DCUUT
δ
−
UUT
:
TVC
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