| Summary: | Sigma-Delta analogue to digital converters are essentially a feedback control system where the loop filter is designed to track the input signal. The tracking error can be improved by either increasing the filter order or by using noise cancellation techniques. Different architectures exist that use either or both of these techniques to produce a highly linear approximation that operates accurately over a high dynamic range. There has been much interest in these architectures because they are small and relatively simple to build. However, it is not easy to fully analyse the systems and the relationship between the performance and the component parameters is not well known. This thesis investigates these analogue to digital converter architectures providing a mathematical analysis and simulation results. A new continuous time analysis of the finite amplifier gain and bandwidth is presented. The results are compared to simulation results of a MASH converter using complex, pseudo continuous time models of the operational amplifier, digital to analogue converter and noise, combined with a discrete time model of a comparator, including hysteresis and the digital post processing. Most of the component parameters of a practical MASH circuit are simulated providing new information on some of the parameters. Such a circuit is then built and the results are compared with the simulations. The simulation models are intended to provide a prototype design tool for the MASH converter but can be extended to any of the architectures. The techniques for data capture and testing of these high performance analogue to digital converters completes the work.
|
|---|
