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2-14
Measurement Concepts
Model 6485 Picoammeter Instruction Manual
Figure 2-9
Equivalent input impedance with zero check enabled
Zero correct
Model 6485 has a zero correct feature to algebraically subtract the voltage offset term
from the measurement (to actually reduce the voltage at the input terminals, see the Volt-
age Offset Correction procedure in
). Perform the following steps to algebra-
ically zero correct the measurement:
NOTE
The ZCOR key toggles zero correct on and off. If zero correct is enabled (“ZZ”
or “CZ” message displayed), press ZCOR to disable it.
1.
Enable zero check (“ZC” message displayed).
2.
Select the range that will be used for the measurement, or select the lowest range.
3.
Press ZCOR to enable zero correct (“ZZ” message displayed).
4.
Press ZCHK to disable zero check.
5.
Readings can now be taken from the display. The “CZ” message indicates that the
displayed reading is zero corrected.
NOTES
With regard to the zero correct feature:
-Model 6485 will remain zero corrected even if it is upranged. If downranged,
re-zero the instrument.
-Model 6485 does not have to be re-zero corrected as long as the ambient tem-
perature remains stable.
-Zero correction cancels the voltage offset term of the amplifier. With both zero
check and zero correct enabled, the instrument may not display a perfectly
zeroed reading.
-If Model 6485 is operating at, or near T
CAL
, zero correction will have very little
effect. T
CAL
is the internal temperature of Model 6485 when it was last cali-
brated.
100pF
Input
Z
F
= 500
Ω
||
200nF....2 mA, 20 mA
50k
Ω
||
2nF .......20
µ
A, 200
µ
A
5M
Ω
||
20pF .....200 nA, 2
µ
A
500M
Ω
||
5pF ...2 nA, 20 nA
12M
Ω
Z
F
Содержание 6485
Страница 1: ...Model 6485Picoammeter Instruction Manual A G R E A T E R M E A S U R E O F C O N F I D E N C E ...
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Страница 44: ...1 20 Getting Started Model 6485 Picoammeter Instruction Manual ...
Страница 66: ...3 6 Measurements Model 6485 Picoammeter Instruction Manual ...
Страница 138: ...9 20 Remote Operation Model 6485 Picoammeter Instruction Manual ...
Страница 159: ...11 CommonCommands ...
Страница 164: ...11 6 Common Commands Model 6485 Picoammeter Instruction Manual ...
Страница 165: ...12 SCPISignalOriented MeasurementCommands ...
Страница 190: ...14 12 SCPI Reference Tables Model 6485 Picoammeter Instruction Manual ...
Страница 214: ...16 14 Calibration Model 6485 Instruction Manual ...
Страница 219: ...A Specifications ...
Страница 221: ...B StatusandErrorMessages ...
Страница 227: ...C GeneralMeasurement Considerations ...
Страница 233: ...D DDCEmulationCommands ...
Страница 247: ...E ExamplePrograms ...
Страница 250: ...E 4 Example Programs Model 6485 Picoammeter Instruction Manual ...
Страница 251: ...F IEEE 488BusOverview ...
Страница 266: ...F 16 IEEE 488 Bus Overview Model 6485 Picoammeter Instruction Manual ...
Страница 267: ...G IEEE 488andSCPI ConformanceInformation ...
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