| The measurement of magnetic field has been used in many technology fields, such as industry, agriculture, national defence, biology, space navigation. With the rapid development of science and technology, more demands have been made of the magnetic measurement. In recent years, it has already brought to the people universal attention with the sensor manufacture and application which use amorphous alloy belts or the wires as the magnetic core. That's because the amorphous alloy has better soft magnetism performance in the magnetic aspect compared with the crystalline state alloy, including such merits:1).High sensitivity;2).A rapid response that the cut-off frequency reaches thousands of Hz;3). high permeability and small magnetic-field-induced magnetic anisotropy constant;4).High reliability, the hysteresis is also smaller after long time use;5). Keep a high stability when the temperature changes.6). High resistivity;Based on such characteristics, amorphous alloy material has been widely used in modern magnetic sensor. In this paper the design of two types of MOS IC-based oscillating circuit micro-magnetic sensor is a good application of the soft magnetic properties of amorphous alloy materials, CoFeNiSiB.The amorphous alloy ribbon is used as the magnetic core of the solenoid, which is produced as a micro-magnetic signal inductor. The external magnetic field change causes the property change of the amorphous alloy material, which induce the change of solenoid parameters, such as inductance, so come to the change of output voltage. The entire process achieves the transformation of non-electric signal to electrical signal. The double-MOS IC-based oscillating circuit belongs to RC square wave oscillator circuit. The circuit has a simple structure, good stability, low cost, and low power consumption. Its oscillation frequency is mainly determined by the capacitance and resistance. The solenoid-made probehead is connected to the output as a load of the circuit, and affects the entire oscillation waveform of the circuit with the change of the external magnetic field. When the sensor works, both the number of the coil turns of the probe and the frequency of oscillating circuit have great impact on the measurement results. So this paper analyses and compares of these two factors. We've done a lot of experiments, and consider the combination of these two factors, so as to find a good match of them, and maximize the performance of the sensor.After obtaining the characteristic curve of the sensor, we do zero adjustment and amplification processing to the results, which makes the sensor be able to measure both the value and direction of the magnetic field. However, after this processing, the sensitivity declined and measurement range narrowed. The measured sensitivity of the sensor achieves 550mV / Oe, measuring range is-1.5Oe ~ +1 Oe.In order to further reduce the costs and simplify the structure of the sensor under the premise of ensuring the sensor's performance, this paper also preliminary designed a single-MOS IC-based magnetic field sensor, which uses only one inverter, yet still work effectively. Its working circuit is Keerpizi-type oscillator circuit. But as the circuit can only start oscillating in the case when the capacitor matches the inductor value, the working circuit is not very Stable. The maximum sensitivity of the sensor is 175mV / Oe, measuring range is 0 Oe ~ +2.9 Oe.In summary, in this paper we designed two types of IC-based magnetic field sensor using co-based amorphous alloy ribbon. They have the same probe structure, but differ in operational principle. The double-MOS IC-based sensor is economical, it has a simple circuit, very stable and reliable performance. The single-MOS IC-based sensor further simplified the structure of the working circuit, and reduced the costs compared with the priorer one. It needs to be better studied and optimized in the future, and has good prospects. |
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