Designing a good thermocouple interface is not easy. There are two main reasons: 1) the output voltage is very small, ranging from a few microvolts per degree up to a few tens of microvolts per degree, and 2) the need to measure the temperature at the cold junction. A complete thermocouple-to-digital circuit is shown using a high-resolution ADC with an internal programmable gain amplifier (PGA), an accurate voltage reference, and a temperature sensor at the cold junction location is monitored to correct for cold junction temperature. The ADC digitizes the  thermocouple output and provides a first-order correction for cold junction error by using the DS600 temperature sensor on the PCB. In general, calibration is necessary to correct for amplifier offset voltage, as well as resistor, temperature sensor, and voltage reference errors, and linearization must be performed to correct for the effect of the thermocouple's nonlinear temperature-voltage relationship. Fortunately for the busy system engineer, Analog Devices provides single chip solutions such as MAX31856 which simplifies the design and provides faster time to market.