Voltage and Temperature Measurements
2-7
Front Autozero
With Front Autozero for the front-end amplifier enabled (which is the default setting), the
Model 2182 performs two A/D measurement cycles for each reading. The first one is a normal
measurement cycle, and the second one is performed with the polarity of the amplifier reversed.
This two-cycle, polarity-reversal measurement technique is used to cancel internal offsets in the
amplifier. With Front Autozero disabled, the second A/D measurement cycle is not performed.
Benefits of Front Autozero disabled:
•
Twice as fast
•
Lower Pumpout Current noise
Drawbacks of Front Autozero disabled:
•
High drift (20µV/°C) in normal voltage mode
•
High offset voltage (±500µV) in normal voltage mode
NOTE
To increase the speed of Delta measurements, disable Front Autozero. The two-
measurement cycle, polarity-reversal technique used by Front Autozero is *not
required for Delta. Delta uses its own polarity-reversal technique to cancel offsets.
Delta measurements are covered in
Autozero
When Autozero for the second amplifier is disabled, the offset, gain, and internal reference
temperature measurements are not performed. This increases measurement speed (a few % at
1PLC). However, the zero, gain, and temperature reference points will eventually drift resulting
in inaccurate readings for the input signal. It is recommended that Autozero only be disabled for
short periods of time.
When Autozero is enabled after being off for a long period of time, the internal reference
points will not be updated immediately. This will initially result in inaccurate measurements,
especially if the ambient temperature has changed by several degrees. A faster update of
reference points can be forced by setting a faster integration rate.
Rate
— With Autozero disabled, pressing the front panel RATE key will change the speed
setting, and will also enable Autozero. Rate changes using remote programming have no effect
on the state of Autozero.
To force a single rapid update of the internal reference points when Autozero is enabled, set
the integration rate to FAST (or 0.01 PLC for remote programming), and then back to the desired
rate (i.e., MED; 1.0 PLC). Details on Rate are covered in
.
Summary of Contents for 2182
Page 1: ...www tek com keithley Model 2182 2182A Nanovoltmeter User s Manual 2182A 900 01 Rev B May 2017...
Page 18: ......
Page 22: ......
Page 23: ...1 Getting Started Getting Started...
Page 41: ...2 VoltageandTemperature Measurements Voltageand Temperature Measurements...
Page 68: ...2 28 Voltage and Temperature Measurements...
Page 69: ...3 Range Digits Rate andFilter Range Digits Rate andFilter...
Page 82: ...3 14 Range Digits Rate and Filter...
Page 83: ...4 Relative mX b and Percent Relative mX b andPercent...
Page 91: ...5 RatioandDelta Ratioand Delta...
Page 117: ...6 Buffer Buffer...
Page 123: ...7 Triggering Triggering...
Page 140: ...7 18 Triggering...
Page 141: ...8 Limits Limits...
Page 149: ...9 SteppingandScanning Steppingand Scanning...
Page 168: ...9 20 Stepping and Scanning...
Page 169: ...10 AnalogOutput Analog Output...
Page 175: ...11 RemoteOperation Remote Operation...
Page 205: ...12 CommonCommands Common Commands...
Page 221: ...13 SCPISignalOriented Measurement Commands SCPISignalOri entedMeasure ment Commands...
Page 225: ...14 SCPIReferenceTables SCPIRefer enceTables...
Page 239: ...15 AdditionalSCPI Commands Additional SCPICom mands...
Page 260: ...15 22 Additional SCPI Commands...
Page 261: ...A Specifications Specifications...
Page 263: ...B Statusand ErrorMessages StatusandError Messages...
Page 268: ...B 6 Status and Error Messages...
Page 269: ...C Measurement Considerations Measurement Consider ations...
Page 278: ...C 10 Measurement Considerations...
Page 279: ...D Model182Emulation Commands Model182 EmulationCom mands...
Page 284: ...D 6 Model 182 Emulation Commands...
Page 285: ...E Example Programs ExamplePro grams...
Page 293: ...F IEEE 488 BusOverview IEEE 488Bus Overview...
Page 307: ...G IEEE 488andSCPI ConformanceInformation IEEE 488and SCPIConform anceInforma tion...
Page 310: ...G 4 IEEE 488 and SCPI Conformance Information...
Page 311: ...H Measurement Queries Measurement Queries...
Page 316: ...H 6 Measurement Queries...
Page 317: ...I Delta PulseDelta and DifferentialConductance Delta Pulse Deltaand Dif ferentialCon ductance...