Analog-to-digital conversion beyond 20 bits

Analog-to-digital converters with resolution exceeding 20 bits are widely available today. They exist in two forms - flexible laboratory instruments and monolithic integrated circuits. We present an overview of application fields for such digitizers, the hardware architectures that implement them, and their limitations. We review the state of the art by comparing the best-performing devices reported in scientific literature, as well as those available commercially. Our focus is particularly on integrated circuit solutions, and among our aims are the disambiguation of the multiple performance metrics in use, as well as the presentation of a clear perspective on basic performance trade-offs. Finally, we provide a discussion on the future prospects for high-resolution digitizing measurement systems.