US Patent 7545136 Device for measuring current

A device for measuring current comprises a magnetic field sensor for measuring the magnetic field produced by a current I flowing through a current conductor and a yoke of a magnetic material with a relative permeability of at least 100. The magnetic field sensor preferably comprises a semiconductor chip with at least one Hall element and an electronic circuit for the operation of the Hall element. The yoke consists of an oblong piece of sheet metal or a laminate of sheet metals with two ends, that has been brought by bending into a form in which the front sides of the ends of the yoke face each other and are separated by an air gap. The ends of the yoke may be flush, tapered, or flayed relative to the width of the yoke.