Implementation of Precise Temperature Measuring System Using Different-Arm Asymmetric Differential Bridge

To solve problems that conventional temperature measuring systems have poor temperature measuring accuracy, a novel precise temperature measuring system using Different-arm Asymmetric Differential Bridge (DADB) is proposed. Firstly, key factors of Output Nonlinearity (ON) of conventional temperature measuring circuit are studied by analyzing output characteristic, and DADB plus its parameter optimal selection are established to suppress ON and improve sensitivity. Secondly, AD module with synchronous sampling and holding function is used to eliminate Nonsynchronous Sampling Errors (NSE), and Forward Reverse Excitation Control (FREC) is designed to calibrate Measuring Deviations (MD) caused by differential amplifier's offset voltage. Last, precise temperature measuring system is implemented, and it is tested in experiments. The experimental results show that its temperature measuring accuracy is much better than ±0.001°C in 0~118°C, and it is widely used in national production and so on.