ADC Requirements for RTD Temperature Measurement Systems

Visit analog.com There are several types of temperature sensors that can be used in a temperature system. The temperature sensor to use depends on the temperature range being measured and the accuracy required. Along with the sensor, the accuracy of the temperature system depends on the performance of the analog-to-digital converter (ADC) to which the sensor is interfaced. A high resolution ADC is required in many cases as the magnitude of the signal from the sensor is quite small. Sigma-delta (Σ-Δ) ADCs are suitable for these systems as they are high resolution devices. They also have additional circuitry embedded on-chip, which is required in a temperature system such as excitation currents and reference buffers. This article describes 3-wire and 4-wire resistance temperature detectors (RTDs) that are commonly used. It describes the circuitry needed to interface a sensor to an ADC along with explaining the performance requirements needed from the ADC.