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Voltmeter Calibration Analysis

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The DC current source uncertainty components listed in Table 2 to Table 5 include both those derived from Eq. 1 and additional systematic components (voltmeter calibration, reproducibility, long-term drift, and loop gain). Each component is explained below. Feedback resistance is the combined standard uncertainty from the QED calibration report, i.e., one half of the expanded uncertainty (k = 2), see Table 1. This is only a relative component (Table 3 and Table 5), there is no absolute uncertainty component (Table 2 and Table 4) for the feedback resistance. Measurement noise is the average “noise” of multiple samples. In Table 2 and Table 4 the measurement noise is defined by the standard deviation of the offset (I = 0) measurement. In…show more content…
2 is shown in Table 6 (absolute term) and Table 7 (relative term). These tables vary by DUT model. For efficiency, the values in the table are determined after evaluating several DUTs of the same model and used for subsequent DUTs of this model if the measurement noise is less than the values in the tables. A similar set of tables is generated for the Keithley 6430 current source (not presented). Table 6. Absolute term for the standard uncertainty budget of the current-to-voltage conversion gain (G(I)) of a DUT using the Keithley 263 DC current source. Absolute standard uncertainty [V x 10-6] Uncertainty components Type Range 1x104 V/A 1x105 V/A 1x106 V/A 1x107 V/A 1x108 V/A 1x109 V/A Current B 7.18 26.3 30.4 26.9 43.6 40.9 Measurement noise A 11.2 22.6 32.7 25.9 41.2 32.4 Voltage measurement B 0.14 0.14 0.14 0.14 0.14 0.14 Reproducibility (6 months) A 0.00 0.00 0.00 0.00 0.00 0.00 Loop gain B 0.00 0.00 0.00 0.00 0.00 0.00 Combined absolute standard uncertainty term of G(I) measurement 13.3 34.7 44.6 37.4 60.0 52.2 Table 7. Relative term for the standard uncertainty budget of the current-to-voltage conversion gain (G(I)) of a DUT using the Keithley 263 DC current source. Relative standard uncertainty [x10-6] Uncertainty components Type Range 1x104 V/A 1x105 V/A 1x106 V/A 1x107 V/A 1x108 V/A 1x109 V/A Current B 3.18 5.81 5.61 6.46 8.57 14.6 Measurement noise A 0.19
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