This paper discusses design considerations for a precision temperature measurement system and how to improve the system’s EMC (electromagnetic compatibility) performance while maintaining measurement accuracy. We will present the test results and data analysis that allow us to easily move from concept to prototype and from concept to market using a Resistance Temperature Detector (RTD) as an example.

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Temperature measurement is one of the most commonly used sensing technologies known in the analog world. Many measurement technologies are available to sense ambient temperature. A thermistor is a small, simple 2-wire implementation with a fast response time, but its nonlinearity and limited temperature range limit its precision and application. An RTD is the most stable and most accurate temperature measurement method. The difficulty of RTD design is that it requires an external stimulus, complex circuits, and calibration work. Engineers  without experience in developing temperature measurement systems may be discouraged. A thermocouple (TC) can provide a rugged, inexpensive solution with varying ranges, but cold junction compensation (CJC) is necessary for a complete system.

Compared to the thermistor, TC, and RTD, a newly developed digital temperature sensor can provide calibrated temperature data directly  through a digital interface. Precision temperature measurement requires high accuracy temperature sensors and a precision signal chain to form a temperature measurement system. TC, RTD, and digital temperature sensors have the highest accuracy. Precision signal chain devices are available and can be used to collect these sensor signals and convert them into absolute temperature.