Table 4-5 summarizes RMS noise, ENOB, and system absolute accuracy error in voltage input mode over the characterized temperature range. The tested input levels were +3.3V, –3.3V, +5V, –5V, +10V, and –10V. For each test condition, 1024 samples were collected for each channel. RMS noise was calculated for each channel and then averaged across the eight channels. ENOB was calculated from the corresponding RMS noise result. System absolute accuracy error was calculated for each measured sample relative to the corresponding DMM reference value. The 1024 calculated accuracy error values were averaged to obtain one accuracy error result for each channel. The reported table value is the average of the eight channel results. In this table, RMS noise is reported as a converted voltage value.

As shown in Table 4-5, RMS noise increases with temperature and with input magnitude. ENOB decreases correspondingly at higher temperature points and larger input levels. This behavior is consistent with the measured noise trend. Across the full characterized range, ENOB remains relatively stable and stays above 19 bits for all tested voltage input conditions.

System absolute accuracy error remains stable over temperature and input polarity. In general, the percentage error is smaller at higher input levels and slightly larger at lower input levels, as expected for a normalized accuracy error metric. Positive and negative input conditions show comparable performance across the characterized range, with no abnormal excursion observed at the temperature extremes.

Figure 4-18 shows the worst-case channel system absolute accuracy error versus temperature in voltage input mode for different input levels. At each temperature point, the accuracy error for each channel was obtained by averaging 1024 calculated sample errors, and the plotted value represents the worst-case channel among the eight channels. In contrast, Table 4-5 reports the average of the eight channel results.

Figure 4-18 Worst-Case Channel System Absolute Accuracy Error vs Temperature in Voltage Input Mode

The results indicate that the worst-case channel system absolute accuracy error is highest at the lowest tested temperature and remains relatively consistent from –20°C to 125°C. As expected for a percentage-based accuracy error metric, the error is generally larger at lower input magnitudes and smaller at higher input magnitudes, with the ±10V conditions showing the lowest error and the ±3.3V conditions showing the highest error. Positive and negative input levels exhibit comparable trends over temperature, indicating balanced performance across input polarity.

Figure 4-19 shows the RMS noise versus temperature in voltage input mode for input levels of +3.3V, –3.3V, +5V, –5V, +10V, and –10V. At each temperature point, the plotted value represents the average RMS noise across the eight channels, where the RMS noise of each channel is calculated from 1024 measured samples.

Figure 4-19 Voltage Input Mode RMS Noise vs Temperature

The results show a clear increase in RMS noise with temperature across all tested input levels. Higher input magnitudes also tend to produce higher RMS noise, with the ±10V input conditions exhibiting the largest values over most of the characterized range. Positive and negative input conditions follow similar trends, indicating consistent voltage input noise performance across input polarity.

Figure 4-20 through Figure 4-22 shows the output distribution histograms for Channel 4 in voltage input mode with a +10V input at –40°C, 25°C, and 125°C. Channel 4 was selected as a representative channel to illustrate the distribution behavior over temperature.

Figure 4-20 Measured Voltage Distribution Histogram for CH4 at +10V at –40℃

Figure 4-22 Measured Voltage Distribution Histogram for CH4 at +10V at 125℃

Figure 4-21 Measured Voltage Distribution Histogram for CH4 at +10V at 25℃

The histograms indicate that the output distribution remains unimodal and approximately Gaussian across the characterized temperature range, with no abnormal distortion or discontinuity observed. The distribution width increases with temperature, which is consistent with the RMS noise trend shown in Figure 4-19. These results indicate stable channel behavior and consistent voltage input noise performance over temperature.