[en] A new noncontacting current sensor with a compact size was developed on the basis of the magnetic bridge principle. The magnetic bridge utilizes the monotonically increasing portion of the permeability of the core together with the flux density. To ensure that the sensitivity of the current sensor is high enough to detect a μA-order current, the magnetic bridge circuit is made in a round shape enclosing a current-carrying conductor. The whole structure of the magnetic bridge current sensor (MBCS) is encapsulated in a thick magnetic shield made of permalloy. The resolution of the current sensor presented in this paper is about 3 μA under an excitation current of 830 μA in 2.5 kHz. Therefore, the interference affecting the measured circuit is reduced to a negligible level. (author)