Chapter 5 - Analog-to-Digital and Digital-to-Analog Conversions

Abstract

This chapter develops an understanding of converting an input analog signal to digital codes or converting digital codes to analog signals. The chapter emphasizes the digit position weighted value in a binary numbering system. This reduction by one-half in weighted digit position value as the bit position is moved to the right continues down to the least significant bit (LSB). The process continues until the input is less than the sum of the weighted values. Then the last digit weighted position value is not added but made equal to zero and a weighted position value of a next bit to the right is added and the total tested again. This process continues until the value is determined or the LSB's value is included, which indicates that the evaluation is complete. The digital code generated at a particular sample is the code nearest the amplitude just exceeded by the signal but not large enough to generate the next code step. These codes from the sampling points appear in sequence at the output of the analog-to-digital converter (ADC) to describe the analog signal. Depending on the ADC, the digital codes may be presented a bit at a time in series, or all bits together in parallel at specific times determined by a timing network.