Platinum-RTD-based circuit provides high performance with few components

摘要

The standard way of using an RTD (resistance-temperature-detector) sensor is to include it in a bridge followed by a differential amplifier. The problem is that two non-linearities-one from the sensor and another from the bridge-affect the transfer function. Some approaches are available that attempt to avoid the problem, but they tend to be bulky and expensive (references 1, 2, and 3). An alternative circuit proposes adding only one extra resistor to the differential amplifier but provides neither design guidelines nor results (Reference 4). This Design Idea fills the gap. Although circuit analysis is somewhat complex, performance is good, and the circuit uses few components.