Accuracy of schematics of older analog ICs

It is an interesting fact that if datasheets of older ( 70’s – 80’s)devices are examined then then it will be found that the datasheet usually includes a detailed device level datasheet. This is more of a case with analog chips. Large analog device manufacturers have been more than generous in providing these with the datasheet as a guide for designers. The issue is though if the schematic is compared to the actual layout ( for example by taking a photo of the die) then many, many discrepancies will be found. This can lead to some very interesting errors in the design of the product with really no help from manufacturer as to why an effect may be seen to happen. In the case of the uA741 for example there are at least two or three different datasheet schematics available. Neither of them are accurate. So user beware. For more information on this topic please contact Signal Processing Group Inc, via their website at

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