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 ¿m CMOS technology. Experimental results show that the sensor interface is able to measure a resistance in the range of 0 ¿ to 200 ¿ with a resolution of 3.5 m¿ (0.009 °C @ t = 0 °C) and a systematic error of 6.8 m¿ (0.018 °C @ t = 0 °C). The measurement time amounts to 110 ms.