Sigma-Delta Converters: Practical Design Guide, 2nd Edition

3 Circuit Errors in Switched‐capacitor Modulators

As discussed in previous chapters, ADCs based on modulation offer key advantages for practical implementation in present‐day CMOS processes compared to other data‐conversion techniques. Unlike Nyquist‐rate converters, which require high precision in their building blocks to achieve overall high accuracy, oversampling and quantization noise shaping allow speed to be traded for accuracy. In this way, an operation that is relatively insensitive to imperfections in the analog circuit can be obtained at the cost of increased complexity and speed in the associated digital circuitry [1].

The principles of modulation were presented in Chapter 1 and alternative M topologies and implementation techniques (DT and CT) were presented in Chapter 2. However, it was only the quantization error that was taken into account when considering the achievable performance of the different alternatives. Besides this error – which is inherent to any analog‐to‐digital conversion technique – only the effect of DAC errors was considered when comparing ...