分析了噪声温度计中相关器的基本原理和特点，设计了一种基于商用数据采集卡和LabVIEW软件的新 型数字相关器，用于极小幅度的热噪声谱的测量。通过调节外部参考时钟的相位，控制相关器两个通道的精确同 步采样，能够实现淹没在测量电路噪声背景下的微弱信号的测量。实验结果表明，该数字相关器设计切实可行，性 能可靠，为噪声温度计测量热力学温度奠定了基础。

The basic principles and characteristics of cross-correlators used in Johnson noise thermometry are described. A new digital correlator is presented based on commercial analog-to-digital converters and Lab VIEW software for the measurement of the thermal noise. High-precision synchronous dual-channel-sampling has been achieved by adjusting the phases of the external reference clocks. Experiments are carried out to validate the proposed approach and the results show that the new correlator is able to detect extremely small signals buried in the noise of the measurement circuits.