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Measurement Considerations
C-9
Meter loading
Loading of the voltage source by the Model 2182 becomes a consideration for high source
resistance values. As the source resistance increases, the error caused by meter loading
increases.
shows the method used to determine the percent error due to meter loading. The
voltage source, V
S
, has a source resistance, R
S
, while the input resistance of the Model 2182 is
R
I
, and the voltage measured by the nanovoltmeter is V
M
.
Figure C-5
Meter loading
The voltage actually measured by the meter is attenuated by the voltage divider action of R
S
and R
I
, and it can be calculated as follows:
This relationship can be modified to directly compute for percent error:
From the above equation, it is obvious that the input resistance of the Model 2182 must be at
least 999 times the value of source resistance if loading error is to be kept to within 0.1%.
V
S
Source
Voltage
+
–
R
S
R
I
V
M
Measured
Voltage
V
M
V
S
R
L
R
I
R
S
+
-------------------
=
Percent error
100R
S
R
I
R
S
+
-------------------
=
Содержание 2182
Страница 1: ...www tek com keithley Model 2182 2182A Nanovoltmeter User s Manual 2182A 900 01 Rev B May 2017...
Страница 18: ......
Страница 22: ......
Страница 23: ...1 Getting Started Getting Started...
Страница 41: ...2 VoltageandTemperature Measurements Voltageand Temperature Measurements...
Страница 68: ...2 28 Voltage and Temperature Measurements...
Страница 69: ...3 Range Digits Rate andFilter Range Digits Rate andFilter...
Страница 82: ...3 14 Range Digits Rate and Filter...
Страница 83: ...4 Relative mX b and Percent Relative mX b andPercent...
Страница 91: ...5 RatioandDelta Ratioand Delta...
Страница 117: ...6 Buffer Buffer...
Страница 123: ...7 Triggering Triggering...
Страница 140: ...7 18 Triggering...
Страница 141: ...8 Limits Limits...
Страница 149: ...9 SteppingandScanning Steppingand Scanning...
Страница 168: ...9 20 Stepping and Scanning...
Страница 169: ...10 AnalogOutput Analog Output...
Страница 175: ...11 RemoteOperation Remote Operation...
Страница 205: ...12 CommonCommands Common Commands...
Страница 221: ...13 SCPISignalOriented Measurement Commands SCPISignalOri entedMeasure ment Commands...
Страница 225: ...14 SCPIReferenceTables SCPIRefer enceTables...
Страница 239: ...15 AdditionalSCPI Commands Additional SCPICom mands...
Страница 260: ...15 22 Additional SCPI Commands...
Страница 261: ...A Specifications Specifications...
Страница 263: ...B Statusand ErrorMessages StatusandError Messages...
Страница 268: ...B 6 Status and Error Messages...
Страница 269: ...C Measurement Considerations Measurement Consider ations...
Страница 278: ...C 10 Measurement Considerations...
Страница 279: ...D Model182Emulation Commands Model182 EmulationCom mands...
Страница 284: ...D 6 Model 182 Emulation Commands...
Страница 285: ...E Example Programs ExamplePro grams...
Страница 293: ...F IEEE 488 BusOverview IEEE 488Bus Overview...
Страница 307: ...G IEEE 488andSCPI ConformanceInformation IEEE 488and SCPIConform anceInforma tion...
Страница 310: ...G 4 IEEE 488 and SCPI Conformance Information...
Страница 311: ...H Measurement Queries Measurement Queries...
Страница 316: ...H 6 Measurement Queries...
Страница 317: ...I Delta PulseDelta and DifferentialConductance Delta Pulse Deltaand Dif ferentialCon ductance...