An Integrated Two-Wire Transmitter with Intrinsic Temperature Sensing Capability

A new integrated two-wire transmitter (TWT) is presented which converts signals from temperature sensors, RTD´s and thermocouples into a industrial standard 4mA to 20mA output. This TWT is unique in that it is a silicon temperature sensor with a standard output which also allows compensation for the cold junction of thermocouples. Although a full-custom design, it is shown that its architecture is also suitable for semi-custom implementation. As a signal conditioner, measured samples of the TWT has shown an accuracy of 0.1% (FS) and nonlinearity of ±0.02%.