为了基于测温电阻实现空间低温辐射计的腔温测量,研究了系统的电子学测量精度和测量稳定度.结合实际电子学需求,进行方案设计和器件选型,提出了一种新型的基于超低噪基准源LTZ1000ACH,四线制柱状锗电阻GR1400-AA和24位模数转换器LTC2400的对偶相消式精密电压测量系统. 对于整个链路信噪比进行了逐级理论计算和分析,并通过电路仿真软件TINA-TI对系统幅频特性和温度响应特性进行了仿真分析,最后在77K液氮环境下对该系统进行了测温精度和长期稳定性测试.实验结果表明:锗电阻实际采样电压值在100 μV内波动,长期测量稳定度达到1×10-5;在77 K液氮环境下,系统测温精度达到4 mK,长期稳定性达到1×10-5.得到的结果基本满足空间低温辐射计电子学部分的设计指标要求.

To implement the temperature measurement of a cavity in the space cryogenic radiometer based on a temperature resistance,the measuring accuracy and measuring stability of the electronic system in the radiometer was researched.By taking the scheme design and device selection into account,a new precise voltage measuring system was proposed based on an ultralow noise accuracy voltage reference source(LTZ1000), a four wire germanium resistance(GR1400-AA )and a 24 bit analog to digital converter(24 bit AD).Then, the noise ratio for the entire system was calculated in theory ,and the temperature characteristics and the amplitude frequency response of the system were simulated by using TINA-TI.Finally,the experiment on measuring temperature accuracy and long-term stability for this system was performed at the 77 K constant temperature environment.The experimental results show that the actual sampling voltage of germanium resistance is within 100 μV,and the long-term stability is lowered to 1×10-5.Moreover,the temperature measurement accuracy of system is less than 4 mK,meanwhile,the temperature stability is up to 1×10-5.So,the proposed precise temperature measurement system basically meets the needs of space cryogenic radiometer for long-term stability and measurement accuracy.