Practical RTD interface solutions
An RTD (Resistance Temperature Device) can be fabricated in several ways, but the most common are based on the temperature characteristics of Platinum. It has a predictable temperature characteristic that can be controlled and configured in a number of different ways.
Platinum wire wound around glass or ceramic and platinum thin film chip designs are common. Many kinds of RTD designs are available to designers but this discussion will be limited to some of the most common.
This application note is intended to review RTD and commonly used interfaces for them. In an industrial environment, longitudinal noise in a wide spectrum may exist requiring good common mode rejection at the circuit interface.
A brief discussion of longitudinal balance and how to improve the interface response to longitudinal noise is presented. Circuit configurations that provide better longitudinal balance along with design recommendations for optimal performance are presented.
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