Chapter 6 - Converters

Abstract

The primary focus of this chapter is converters and its operations. The internal construction is glanced at because it is relevant to operational advantages or limitations. There are two basic types of converters, digital-to-analog (DACs or D/As) and analog-to-digital (ADCs or A/Ds). In the case of DACs, they output an analog voltage that is a proportion of a reference voltage, the proportion based on the digital word applied. In the case of ADCs, a digital representation of the analog voltage that is applied to the ADCs input is outputted, the representation proportional to a reference voltage. In both cases the digital word is almost always based on a binarily weighted proportion. The digital input or output is arranged in words of varying widths, referred to as bits, typically anywhere from 6 bits to 24 bits. In a binarily weighted system each bit is worth half of the bit to its left and twice the bit to its right. The greater the number of bits in the digital word, the finer the resolution. These bits are typically arranged in groups of 4, called bytes, for convenience. The operation of converters primarily from a “black box” view is discussed. The difference between accuracy and resolution is to be kept in mind. The resolution of a converter is the number of bits in its digital word. The accuracy is the number of those bits that meet the specifications.