Characteristics and applications of magnetic sensors

The magnetic sensing element is a semiconductor device that is extremely sensitive to magnetic fields. Typical magnetic sensing elements are magnetic sensitive diodes, magnetically sensitive contactless potentiometers, and the like. Here, only a magnetic sensitive diode is taken as an example.

Magneto-sensitive diodes are made using the principle that carriers are subjected to the action of Lorent's magnetic force during the movement of the magnetic field. The structure of the magneto-sensitive diode is as follows: a piece of high-purity semiconductor silicon or germanium close to the intrinsic, both ends are made of P+ and N+ by alloy or diffusion method, and the middle interval is longer near the intrinsic region (intrinsic area) The length of the large dry holes and the diffusion length of the electrons) form a P+-I-N+ structure, and a high recombination region r is formed on the side of the intrinsic region by a process such as grinding or diffusion, thus forming a magnetic sensitive diode. When the magnetic diode is working normally, it is the same as the general diode, and it is required to connect the positive pole of the power supply at the P+ terminal. The N+ terminal is connected to the negative pole of the power supply and has unidirectional conductivity.

When the magnetic sensitive diode is connected to the working voltage and is in the magnetic field, the resistance of the magnetic sensitive diode changes with the change of the magnetic field strength and the magnetic field direction, so that the current flowing through the magnetic sensitive diode also changes with the magnetic field. And change. According to this feature, magneto-sensitive diodes are used to detect the presence or absence of a magnetic field. Magnetic sensors can also be used in tape tension control, aerospace, automotive, electronics, instrumentation and other fields.