Hi Edu, They are using DDC112U (DW package). They get the output data every 0.1s(100ms) for 20 seconds. So total data count is 200. 1.81527pA is average value of those data. Also the standard deviation is calulated from those data. "So, they basically listed 3 channels that look similar to others and 3 that look off, correct?" -> Correct. "Looking at the difference between what they call a normal channel (in average 1.81353) and an outlier (in average 1.816916), it looks like it is 0.00338pA which would translate into 7 codes. That looks really small to me... Are we reading this right?" ->I think so and the customer beleives the data is correct. They want to know what is this phenomenon (data averages can be categolized clearly to two groups as 98% lower data grop and 2% higher data grop) cause. Do you have any answer? "And how do they compute those currents? As you know, the device measures charge, so, I want to know if they are subtracting or not the 0.4% offset (output 4095) on their calculation. I.e., 1.81527e-12*100e-3/50e-12*2^20=3807 codes. Did they get that code as output (3807) or actually they got 3807+4095=7901?" -> I will ask them this. "The other important thing to take into account with those long integration times (100ms) they need to watch for ibias which has a typical of 0.1pA but a max of 10pA. I suspect that this may be because it is not measured in production and they just placed a wide margin, so, I would not expect it to be like that for most of the units, but we have seen outliers in this kind of spec before in a different DDC (not DDC112 ). So, if that ibias varies from channel to channel by 0.1pA, it is already bigger than what they call "outlier". -> If the customer tries to measure the output data with other integration time, what integration time is better to try? 50ms? 20ms? 1ms? Could you please recommend me which time is better? I will ask them to measure the output data when I get your recommend time. Thank you very much again and best regards, Kazuya Nakai.
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