This paper presents the implementation of an electronic fully-digital impedance bridge optimized for RC comparisons with equal impedance magnitudes, together with an evaluation of the uncertainty. This bridge has been designed with the goal of realizing the farad directly from the quantum Hall effect with a bridge uncertainty component at the 10⁻⁷ level. Thanks to its simple design, ease of operation and affordability, this bridge is suitable to be industrially manufactured. Together with the increasing availability of graphene quantum Hall resistance standards, this can provide an affordable quantum realization of the unit farad for metrology institutes and calibration centres.

In this paper we present the uncertainty budget of an example measurement and the results of the validation of the bridge against a suitably modified version of the traceability chain of the Italian national standard of capacitance. The combined uncertainty of the bridge resulted from repeated measurements (overall measurement time of about 200 min) is 9.2 10⁻⁸, suitable for the primary realization of the unit of capacitance from a quantized Hall resistance standard. The crosstalk among the channels of the electrical generator is the most significant uncertainty component, possibly reducible with internal shielding and filtering of the electronic generator.

本文介绍了一种电子全数字阻抗电桥的实现，该电桥针对具有相等阻抗幅度的RC比较进行了优化，并评估了不确定性。该电桥的设计目标是直接从量子霍尔效应中实现法拉，其电桥不确定性分量为 10 ^-7水平。由于其简单的设计、易于操作和价格合理，该桥适合工业化制造。再加上石墨烯量子霍尔电阻标准的日益普及，这可以为计量机构和校准中心提供负担得起的单位法拉量子实现。

在本文中，我们介绍了示例测量的不确定度预算以及根据意大利国家电容标准的可追溯链的适当修改版本验证电桥的结果。重复测量（总测量时间约为 200 分钟）产生的电桥组合不确定度为 9.2 10 ^-8，适合从量化霍尔电阻标准初步实现电容单位。发电机通道之间的串扰是最重要的不确定性分量，可能通过电子发电机的内部屏蔽和滤波来减少。