The established calibration of the transresistance of the ultrastable low-noise current amplifier (ULCA) directly involves a cryogenic current comparator (CCC). Here, we present an alternative approach based on a calibrated set of three resistors and three digital voltmeters. This approach was experimentally verified for a two-channel ULCA with nominally 1 G transresistance using PTB's travelling 12-bit CCC setup in an on-site comparison at METAS. Series of interleaved experiments included calibrations of the input and output stages of two different ULCA channels. The consistency found between the conventional calibration with PTB's CCC and calibration with METAS' set of three resistors – each traced to the quantum Hall resistance with METAS' CCC – confirms that the alternative traceability chain provides valuable results. If the standard resistors are calibrated without using a CCC, the new method even opens the possibility to calibrate the ULCA without any CCC in the traceability chain involved, however, typically at the expense of increased uncertainty.

中文翻译：

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无需直接使用低温电流比较器即可校准超稳定低噪声电流放大器

超稳定低噪声电流放大器 (ULCA) 跨阻的既定校准直接涉及低温电流比较器 (CCC)。在这里，我们提出了一种基于一组校准的三个电阻器和三个数字电压表的替代方法。在 METAS 的现场比较中，使用 PTB 的移动 12 位 CCC 设置，对标称 1 G 跨阻的双通道 ULCA 对这种方法进行了实验验证。一系列交错实验包括校准两个不同 ULCA 通道的输入和输出级。使用 PTB 的 CCC 进行的常规校准与使用 METAS 的三个电阻器组的校准之间发现的一致性——每个都使用 METAS 的 CCC 追踪到量子霍尔电阻——证实了替代可追溯性链提供了有价值的结果。