Closed-loop tmr magnetic field measurement device based on power-on setting

Abstract

A closed-loop TMR magnetic field measurement device based on power-on setting, including a TMR magnetic sensor, a differential to single-ended chip, an integrating circuit, a V / I conversion circuit, an excitation circuit, and a feedback wire. The feedback wire is arranged below the TMR magnetic sensor, and the magnetic field generated by the feedback wire is parallel to the sensitive axis of the TMR magnetic sensor; the signal output end of the TMR magnetic sensor is connected to a differential to single-ended chip, and the differential to single-ended The terminal chip is connected to the integral circuit, and the output end of the integral circuit is connected to the feedback wire after being converted by the V / I conversion circuit to form a closed loop; the V / I conversion circuit includes a feedback resistor for adjusting the size of the feedback current in the closed loop; Both the feedback wire and the V / I conversion circuit are connected to the excitation circuit. The device of the invention adopts a closed-loop structure, and by designing the feedback wire and arranging it under the TMR sensor chip as a setting and feedback element, the magnetic field compensation is performed on the TMR sensor from the hardware, thereby suppressing the hysteresis of the sensor and improving its sensitivity.

Description

technical field [0001] The invention relates to the technical field of magnetic field measurement, in particular to a closed-loop TMR magnetic field measurement device based on power-on and reset. Background technique [0002] The geomagnetic field is a weak vector field. As a natural magnetic source existing on the earth's surface, it has a wide range of uses and plays an irreplaceable role in many fields such as military affairs and aviation. For weak magnetic field measurement, a high-precision magnetic field measurement device is essential. It is mainly made of a magnetic field sensor as a sensitive element and combined with a corresponding signal conditioning circuit. Therefore, choose a suitable magnetic field sensor and design a simple and effective signal The optimization of the conditioning circuit is an important guarantee for the development of a high-performance magnetic field measurement device. [0003] At present, the commonly used magnetic field sensors incl...

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Problems solved by technology

In practical application, the magnetic field measurement device with TMR sensor as the sensitive element often adopts an open-loop signal conditioning circuit, which has the advantages of small size and simple structure, but the TMR sensor is composed of magnetic multilayer thin film materials. It determines that it has a large hysteresis. For example, the TMR9001 sensor has a hysteresis of 0.1Oe within the magnetic field range of ±0.5Oe, which has a great impact on the performance of the magnetic field measuring device designed with it as a sensitive element. However, the signal conditioning circuit of the open-loop structure can only simply process the output signal of the sensor, but cannot solve its hysteresis problem.

[0004] For the hysteresis problem of TMR sensors, the existing suppression methods are mainly divided into two aspects: one is to establish a corresponding sensor output hysteresis model on the basis of physical or mathematical principles to obtain the local hysteresis curve of the sensor, and then It is compensated by an algorithm, but due to individual differences in sensors, different hysteresis mathematical models need to be established for different sensors, so this method is not suitable for mass production

The second is to start from the internal causes of hysteresis, by developing new sensitive materials to fundamentally reduce the hysteresis of the sensor or by adopting a new production process to change the hysteresis. For example, some literature has found that different annealing temperatures can change the material The hysteresis of the sensor, however, while the above method reduces the hysteresis of the sensor, it often causes the loss of other performances of the sensor

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