Preface

Digital technologies aim towards ever smaller, faster, less consuming transistors to lead to increasingly complex integrated digital systems. Consequently, many of the functions obtained through the use of analog integrated circuits are now entrusted to digital circuits. This has reaped substantial benefits regarding accuracy with no sensible penalty as far as area and power consumption are concerned. The input data are often analog however so that high performance imbedded D to A and A to D converters are required unless already integrated within the sensors linking the system to the outside world.

Converters are essential parts that enable communication between the external analog world and the digital silicon chip. They should not compromise precision even though the hardware in which they are implemented relies on semi-conductor devices known for their poor accuracy. Therefore, converters capitalize design expertise accumulated during the last to circumvent the limitations and impairments inherent to integrated circuits.

The objective of this book is not only to review the principal converter architectures, but also to bring to forward many of the innovative solutions suggested throughout time to reach high performance. This is why some circuits, nowadays obsolete, but essential stepping stones in the process of development, are still reviewed. Their merit lies in their ability to illustrate the basic principles upon which progress became possible. To this end, in addition to detailed presentations of the various types of converters, this book also exemplifies the evolution designers went through in order to cope with the inherent integration limitations. Converters offer a remarkable opportunity in this respect. They make the most of the hardware and software techniques available to enhance the performances of integrated circuits.

The book is divided in eight chapters. Definitions and evaluation techniques are dealt with in Chapter 1; parallel D to A converters in Chapters 2 and 3; serial A to D converters in Chapters 4, 5 and 6; stochastic A to D and D to A converters in Chapter 7; and flash, multi-step, pipelined and folding A to D converters in Chapter 8.