An Accurate Readout Circuit for Sensors Based on Thermopiles/Thermocouples

摘要

A measurement system optimized for low level voltage output sensors such as thermocouples and thermopile has been designed and implemented. From system level to transistor level, different design optimizations have been carried out to reach the highest system performance. The systematic analyses of the error sources and the techniques to reduce their effect have been presented. By applying the auto-calibration technique, a nonlinearity of below 0.06% has been achieved even with the presence of a 10 kΩ source resistance. The circuit can finish a complete measurement within 0.5 ms, which is much faster compared with the previous work. So it is suitable for a much wider range of applications. When increase the measurement time to above 150 ms, the resolution becomes better than 1 μV.