Digitally corrected multi-bit ΣΔ data converters

ΣΔ data converters using multibit internal A/D and D/A converters (noise-shaping converters) have lower quantization noise and are more stable than the usual single-bit systems. However, the required linearity of the internal multibit digital-to-analog converter (DAC) is very difficult to achieve for an untrimmed integrated converter. A description is given of several novel multibit ΣΔ converters which use digital correction schemes to cancel the errors due to the nonlinearity of the internal DAC. Simulation and experimental results are given. They verify the high accuracy achievable with the proposed systems