As in any electrical system, the structure produces noise. In this article, we examine the resulting noise from a digital-to-analog converter (DAC) system. The DAC system design goal is to minimize the various noise sources as much as possible to achieve optimal performance. To achieve this we start by examining the three major sources of noise contribution: 1) DACís internal resistor string and feedback resistor; 2) output amplifier; and 3) voltage reference (Figure 1).
Three primary DAC noise sources: internal DAC resistance, output amplifier, and voltage reference.
This article examines the DAC internal-resistances and output-amplifier noise issues. The next article in this DAC Basics series will examine the impact of the voltage reference noise.
Note that other noise sources can impact the DAC system noise, such as power supply transients and cleanliness of the ground layer. The design of well-regulated supplies and proper layout mitigate the impact of these noise sources. Discussing power and layout noise is beyond the scope of this article.