Reverter Ferran
Department of Electronic Engineering, Universitat Politècnica de Catalunya-BarcelonaTech, 08860 Castelldefels, Spain.
Sensors (Basel). 2024 Jan 10;24(2):422. doi: 10.3390/s24020422.
This article proposes and experimentally characterizes two implementations of a novel front-end circuit for three-wire connected resistive sensors with a wire-resistance compensation. The first implementation relies on two twin diodes, whereas the second on a switch; in both cases, those devices are non-remote (i.e., they are placed at the circuit end). The two circuit proposals have a square-wave input excitation so that a constant current with the two polarities is alternatively generated. Then, depending on that polarity, the current goes through either the sensor and the wire parasitic resistances or just the parasitic resistances. This generates a square-wave bipolar output signal whose average value, which is obtained by a low-pass filter, is proportional to the sensor resistance and only depends on the mismatch between two of the three wire resistances involved. Experimental tests applied to resistances related to a Pt100 thermal sensor show a remarkable linearity. For example, the switch-based front-end circuit offers a non-linearity error lower than 0.01% full-scale span, and this is practically insensitive to both the presence and the mismatch between the wire resistances.
本文提出并通过实验表征了一种用于三线连接电阻式传感器的新型前端电路的两种实现方式，该电路具有线电阻补偿功能。第一种实现方式依赖于两个双二极管，而第二种则依赖于一个开关；在这两种情况下，这些器件都是非远程的（即它们放置在电路末端）。这两种电路方案都有一个方波输入激励，以便交替产生具有两种极性的恒定电流。然后，根据该极性，电流要么流经传感器和线路寄生电阻，要么仅流经寄生电阻。这会产生一个方波双极输出信号，其平均值通过低通滤波器获得，该平均值与传感器电阻成正比，并且仅取决于所涉及的三根线路电阻中的两根之间的不匹配。应用于与Pt100热传感器相关电阻的实验测试显示出显著的线性度。例如，基于开关的前端电路提供的非线性误差低于满量程跨度的0.01%，并且实际上对线路电阻的存在和不匹配都不敏感。
