Measure RTD Sensors without a Precision Current Source (.PDF Download)

Traditionally, resistance-temperature-detector (RTD) sensor resistance is measured by applying a precision current source and measuring the developed voltage. This approach usually requires a precision voltage reference to create then current source, followed by a high-quality analog-to-digital converter (ADC) to measure the voltage.

This isn’t difficult to achieve at room temperature, but when you consider that the temperature of your measuring system can be in the range of −40 to +55 C°, the task becomes more daunting.