A40B
Instruction Manual
26
TVC Sensitivity Characterization
The voltage output of a SJTVC output is proportional to the square of the applied
voltage. Thus the device is inherently non-linear and transresistance gain or sensitivity
changes with input current. Sensitivity characterization minimizes the resulting errors by
determining mean sensitivity in a narrow band ±500 ppm from the nominal current.
Sensitivity characterization is performed before UUT calibration with the system
configured as for UUT measurement (Figure 7). Figure 9 shows the characterization
sequence w
here:
Vin is the setting on the 5720A
Vin_1 = n 500 ppm
Vin_2 = nominal - 500 ppm
Vin_3 = n 500 ppm
Vout_1 , 2 and 3 are the voltages reported by the measuring devices.
The gain factor
n
is a measure of the sensitivity of the device used to measure the output
voltage
Apply Nominal
value + 500 ppm
Measure Vout
V
out_1
Apply Nominal
value - 500 ppm
Measure Vout
Delay
Apply Nominal
value + 500 ppm
V
out_2
Start
End
Measure Vout
Delay
V
out_3
V
in_1
V
in_2
Delay
V
in_3
feh022.eps
Figure 9. Characterizing Sensitivity
1
2
1
2
)
ppm
in
(
)
ppm
in
(
factor
Gain
2
_
3
_
1
_
2
_
3
_
1
_
−
×
+
−
×
+
=
Δ
Δ
=
IN
IN
IN
OUT
OUT
OUT
V
V
V
V
V
V
Vin
Vout
η
The +500 ppm measurement is performed twice to counter drift in the measurement.
Summary of Contents for A40B
Page 6: ...A40B Instruction Manual iv...
Page 8: ...A40B Instruction Manual vi...
