Adaptive Cancellation of Static and Dynamic Mismatch Error in Continuous-Time DACs

Abstract

Inadvertent but inevitable mismatches among nominally identical unit element 1-bit digital-to-analog converters (DACs) within a multi-bit Nyquist-rate DAC cause both static and dynamic error in the DAC’s continuous-time output waveform. Prior calibration techniques are able to suppress static mismatch error, but have had limited success in suppressing dynamic mismatch error. This paper presents a digital calibration technique that adaptively measures and cancels both static and dynamic mismatch error over the DAC’s first Nyquist band. The technique is capable of either foreground or background operation, and is relatively insensitive to non-ideal circuit behavior. The paper presents a rigorous mathematical analysis of the technique, and demonstrates the results of the paper with both behavioral and transistor-level circuit simulations.