All analog-to-digital converters (ADCs) and digital-to-analog converters (DACs) require a reference signal, usually a voltage. In this article, learn about the basics of voltage references, then find out more about the key things to consider when selecting one for your design.
Key pieces of information to consider when beginning the process of choosing a voltage reference:
Q: How good must a voltage reference be?
A: In short, it depends on the system. A question to ask is “what is the goal of your system?” If absolute accuracy is needed, it may be a requirement to take voltage reference readings in a temperature-controlled area to eliminate the chance for voltage variations caused by temperature fluctuations. If stability or repeatability are desirable, it might lead to the selection of a different type of reference.
Q: What precautions should I take when using voltage references?
A: Remember the basics of good analog circuit design: beware of voltage drops in high impedance conductors, noise from common ground impedances, and noise from inadequately decoupled supply rails. Consider in which direction the reference current is flowing, and be careful of capacitive loads.
Q: Does using these high precision references instead of its internal reference make a converter more accurate?
A. Not necessarily. Some modern regulators have internal references that are plenty accurate on their own. However, depending on the complexity of the system and its measurement demands, it might make sense to incorporate a separate voltage reference into your design.
For more in-depth discussions of these topics, plus many more, click through to the article.