ADC Design at Black-Box Level

Up till this point, the book has focused on filtering for the application of proposed concepts for high-accuracy design using switched capacitors. Now the focus shifts to analogue-to-digital converter (ADC) design, which is the second most important application area for SC techniques. To start off, this chapter deals with the design of the ADC at the generic black-box level. Firstly, the most important performance specifications are explained and formulated. The signal processing of the ADC can be broken down into three basic functions, namely the anti-aliasing pre-filter, the sampler, and the quantizer. Although the anti-aliasing filter is not fundamental to the ADC operation, some form of analogue pre-filtering is almost always needed due to the sampled-data operation of the ADC. The signal path of the black-box ADC is shown in Fig. 7.1. Each of the ADC sub-blocks are examined and modelled, in this chapter, for how they affect the quality of the conversion process from analogue to digital. Finally, models are proposed to represent the ADC conversion efficiency. Limits are derived for the minimum signal-to-noise ratio and minimum power of the generic ADC.