The first two chapters of this book set the stage for the following ones. This chapter covers some of the most advanced and recent architectures and circuit techniques for analog-to-digital conversion.

Certain classic ADC architectures have recently seen renewed interest and, in fact, have gained something like a “new life” when researchers and designers rediscovered them as very valuable options to push the converters' performance, especially as deep CMOS scaling begins to offer serious challenges to switch capacitor ADCs using precision amplifiers. The renaissance of these “forgotten” ADCs is the topic of Section 3.1.

Progress in analog-to-digital conversion, however, has certainly not relied only on rediscovering and modernizing old tools and techniques. A few emerging architectures and techniques that certainly break away from tradition to a larger degree are discussed in Section 3.2. Most of these, however, are still somewhat in their “incubation” stage since to date there aren't many commercial stand-alone ADCs based on them. This section offers a look at what the imminent future of ADCs could be.

Another recent trend in this field has been associated with the proliferation of hybrid architectures, namely ADCs whose architecture is not a single classical one (e.g. a pipelined ADC, a ΔΣ ADC, a flash ADC etc.) but rather a combination of two or more into a single converter. The idea is that, on carefully combining two or more architectures, the resulting one would have the advantages of both and then achieve better overall performance than if either one or the other had been adopted.