Precision Temperature Readout Using Solid-State Electronics

摘要

Precision temperature measurement with SPRTs and RTDs requires a readout device that can accurately measure resistance. Resistance ratio transformers are often used for this purpose. Although they presently offer the greatest accuracy, the drawbacks to resistance ratio transformers are that they're large, expensive, slow, and difficult to operate. A readout instrument that uses solid-state electronic components offers significant advantages with regard to size, cost, speed, reliability, and simplicity. Recent advances in solid-state electronic components have also made it possible to achieve an accuracy up to 4 ppm using these devices which is excellent for many temperature calibration applications. The purpose of this paper is to describe a practical approach that uses solid-state electronic components to accurately measure the resistance of SPRTs and RTDs and thus temperature. The functions and requirements of the components are described in general. Causes of error, such as thermoelectric offsets and component nonlinearity, are evaluated and techniques for reducing their effects are discussed.