Digital self-correction of time-interleaved ADCs

A well known problem of time-interleaved ADCs is the matching between the individual channels. Any mismatch affects the accuracy adversely. The random mismatch between the channels originates mainly from the mismatch of components like transistors and capacitors. To achieve a certain degree of matching between the channels, the sizes of the individual components have to be chosen accordingly. Especially for high-resolution ADCs, this means that physically large transistors are required. Instead, one can also start with an analog circuit that is relatively inaccurate in itself (allowing physically small devices), and use a digital post-correction technique to correct for the actual deviations of each component. With this method, a high accuracy can be obtained while the requirements for the components are relaxed significantly. Although these techniques have been available for single-channel converters for many years, techniques correcting the mismatch between several channels are scarce. In this paper, an existing algorithm for single-channel pipelined ADCs is extended to include inter-channel correction as well, requiring almost no additional hardware.