The temperature measurement accuracy of the conventional four-wire constant current source driven temperature measurement system is very low due to the interference factor of temperature current drift,it is difficult to exceed the order of 0.1 C.An improved four-wire high-precision temperature measurement circuit driven by constant current source was designed based on PT100.By sampling the ratio of high precision resistance voltage of high temperature stability coefficient to platinum resistance voltage,the current variation of constant current source due to temperature drift and other factors were eliminated,so that the output voltage ratio has a good linear relationship with the platinum resistance.The signal was sampled by LTC2492A/D converter and transmitted to ATMEGA32 which processed,stored and displayed the data.The experimental results show that the temperature measurement accuracy and stability of the circuit can reach within 5‰,which is consistent with the theoretical value.%普通四线制恒流源驱动测温系统受温度电流漂移等影响,温度测量准确率很低,很难超过0.1℃量级.基于PT100设计了一种改进的恒流源驱动四线制高精度温度测量电路,通过采样温度稳定系数高的高精密电阻的电压和铂电阻电压的比值,消除了恒流源由于温度漂移等因素影响的电流变化,使得输出电压比值与铂电阻成良好的线性关系.利用LTC2492A/D转换器对信号进行采样,将信号传送给ATMEGA32单片机,单片机进行数据处理并保存和显示数据.实验测试结果表明,该电路温度测量的精度和稳定性均可以达到5‰之内,与理论值一致.
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