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Measurement Concepts
Model 6485 Picoammeter Instruction Manual
B) SYSTem:ZCORrect[:STATe] <b>
This method to perform zero correction is consistent with the way it is performed from the
front panel. That is, zero correction is performed while zero check is enabled. The zero
correct state can be turned on and off repeatedly without requiring. If no ACQ has not been
performed since the most recent reset, zero is used for the ACQ value.
Measurement considerations
There are a variety of factors to consider when making low level measurements. These
considerations are listed and summarized in
. For comprehensive information on all measurement considerations, refer to the
Low Level Measurements handbook, which is available from Keithley Instruments.
Table 2-5
Summary of measurement considerations
Considerations
Description
See
Input bias current
Offset current of Model 6485 could affect low current measurements.
Voltage burden
Offset voltage of Model 6485 could cause errors if it is high in
relation to the voltage of the measured circuit.
Noise
Noise generated by source resistance and source capacitance.
See
for details
Ground loops
Multiple ground points can create error signals.
Triboelectric effects
Charge currents generated in a cable by friction between a conductor
and the surrounding insulator (i.e. bending a triax cable).
Piezoelectric and stored
charge effects
Currents generated by mechanical stress on certain insulating
materials.
Electrochemical effects
Currents generated by the formation of chemical batteries on a
circuit board caused by ionic contamination.
Humidity
Reduces insulation resistance on PC boards and test connection
insulators.
Light
Light sensitive components must be tested in a light-free
environment.
Electrostatic interference
Charge induced by bringing a charged object near your test circuit.
Magnetic fields
The presence of magnetic fields can generate EMF (voltage).
Electromagnetic interference
(EMI)
EMI from external sources (i.e. radio and TV transmitters) can
affect sensitive measurements.
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Страница 44: ...1 20 Getting Started Model 6485 Picoammeter Instruction Manual ...
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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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