A three-dimensional Hall sensor with integrated coils for sensitivity control and volume testing is described in this article. A special way of operation allows for adjusting the sensitivities for all three magnetic flux components of the sensor, even during measurements. By exposing all orthogonal sensor directions to a magnetic field at the same time, the matching of the different sensitivities is guaranteed, even if the absolute value of the excitation current is unknown. This is of prime importance for further signal processing. In many applications such as rotary encoders, for example, the angle is calculated from two orthogonal flux components. A sensitivity mismatch between these orthogonal sensors of only 1 per cent leads, in worst instance, to an absolute error of 0.3 degrees. Measurements at our Institute show that even with sensitivities adjusted at room temperature the matching between the horizontal and vertical Hall sensors can vary by about ten per cent in a temperature range from −40 °C to 140 °C. This leads to an absolute error of 2.3 degrees. By adjusting the direction-dependent sensitivities versus temperature by means of the integrated coils, we reach an absolute error better than 0.2 degree.
The growing interest and activity in the field of sensor technologies requires a forum for rapid dissemination of important results: Sensor Letters is that forum. Sensor Letters offers scientists, engineers and medical experts timely, peer-reviewed research on sensor science and technology of the highest quality. Sensor Letters publish original rapid communications, full papers and timely state-of-the-art reviews encompassing the fundamental and applied research on sensor science and technology in all fields of science, engineering, and medicine. Highest priority will be given to short communications reporting important new scientific and technological findings.