CURRENT MEASUREMENTS BASED ON THIN-FILM MAGNETORESISTIVE SENSORS

As is well known, the magnetoresistive effect is the basic principle of a large number of sensors. The potential-free measurement of current is one way of applying magnetoresistive sensors. For the measurement of currents lower than about 50 A, it is necessary to reduce the distance between the conductor and the magnetoresistive sensor to one millimeter or less. We have developed two different kinds of current-sensor devices containing both a conductor and a sensor. The first one is a hybrid magnetoresistive current sensor suitable for measurements of currents between 1 and 10 A. This device contains a barberpole elementary magnetoresistive sensor chip and the conductor, and also a permanent magnet in order to generate the stabilizing magnetic field. The second device, suitable for the measurement of currents between 1 and 30 mA, contains a sensor chip with integrated thin-film conductor and a thin-film insulator between the conductor and magnetoresistive layer. The advantages and disadvantages of our sensor devices are described and the typical sensor parameters are explained.