A new silicon micro-transducer for the measurement of the magnitude and direction of a magnetic-field vector

This paper describes a new Silicon Micro-Transducer (SMT) which is capable of measuring the magnitude and direction of a magnetic-field vector. This vector sensor --made by standard bipolar technology-is a four-collector npn-transistor giving output signals which are a linear function of the two components of an in-plane magnetic field. A centrally injected current is divided into four equal parts. The current differences of the two pairs of opposite collectors, affected by the two in-plane field components, are the output signals. Consequently, the amplitude and direction of the applied field can be derived from these independent signals. The vector sensor was developed from a one-dimensional sensor having two collectors only. As the basic operating principles are the same, most of the one-dimensional characteristics also apply to the vector sensor. Non-linearity: ≤ 0.3% for |B| ≤ 1 T. Typical sensitivity per collector pair: δIc/(Ic.B) = 3 × 10^-2T^-1at Ucb= 5 V.