1-D and 2-D switching strategies achieving near optimal INL for thermometer-coded current steering DACs

It is known that thermometer coded current steering DACs have very small DNLs but much larger INLs, even with the best switching strategies available in the literature. In this paper, we present algorithms for generating near optimal 1-D switching strategies for any types of gradient errors and 2-D switching strategies for linear gradient errors. In both cases, the new switching strategies result in total INL that is less than the DNL. This is far less than what was achievable by existing switching strategies and is very close to the absolute lower limit of 1/2 DNL.