A High-Performance Interface For Platinum Temperature Sensors With Long-Cable

This paper presents a low-cost, high-performance sensor interface for resistive platinum temperature sensors with a long connection cable. The interface design is based on the use of a relaxation oscillator. The effects of interference and parasitic elements are reduced by applying some classical and new measurement techniques in the sensor interface design. The sensor is supplied with a DC excitation signal, which allows the use of a very long cable for the sensor connection. Meanwhile, the advanced chopping technique reduces the effect low-frequency interferences. The sensor interface has been manufactured with 0.7 mu m CMOS technology. Experimental results show that the sensor interface is able to measure a resistance in the range of 0 Omega to 200 Omega with a resolution of 3.5 m Omega (0.009 degrees C @ t = 0 degrees C) and a systematic error of 6.8 m Omega (0.018 degrees C @ t = 0 degrees C). The measurement time amounts to 110 ms.