Hi Kazuya-san, Thank you for the conditions. Do you know which one is their exact part number? I mean, U/Y version or UK/YK? It is a bit different in the spec. Also, can you ask them what do they mean for output data and standard deviation. I.e., for instance, is 1.81527pA the output value of one DDC112 channel and 0.02865 (pArms?) the noise for that channel? I would think so, but just making sure... So, they basically listed 3 channels that look similar to others and 3 that look off, 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? 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? A small issue we have looking at this data is that it is taken at Range 1 (50pC FSR) but offset error spec is given in Range 5 (250pC), so, it is difficult to know if it is within spec or not. The first number above (3807) would be pretty close to the ideal 4095 and actually would be close to typical spec (+/-200). The 2nd number (7901) is quite far. I would have to check here, but maybe the Range 1 as it is 5 times more sensitive can result on wider offset spec. No idea... 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". To see if ibias is the culprit, they could change the integration time and see how it varies the output. Offset does not change with integration time, while the effect of ibias gets bigger with integration time... Also to note that if it was ibias, the effect would get worse with temperature (roughly 2x increase for every 10C T increase) Nevertheless, I am thinking we still missing something as again, we are talking only about 7 codes difference in average which looks very small... So, I'll stop speculating here and wait for your answers... May also have done some math error but please feel free to double check these numbers. Best regards, Eduardo
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