Research on Characteristics of Monolithically Integrated Magnetic Field Sensor for Angular Measurement

To enable non-contact angular measurement through magnetic sensitive devices (Silicon magnetic sensitive transistor, SMST), a monolithically integrated magnetic field sensor is proposed. The devices with oppositely arranged magnetic sensitivity directions are paired to form magnetic sensitive units (MSU) for measuring the components of the externally applied magnetic field <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> within the horizontal plane in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> directions, i.e. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_x</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_y</i>. When the magnetic field <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> rotates synchronously with the measured object, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i>-MSU and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i>-MSU generate corresponding voltage signals in response to changes in the magnetic field components. The rotational angle θ of the measured object can be indirectly determined by performing inverse trigonometric calculations on the electrical signals output by the sensor. The sensor chip was fabricated and packaged employing micro-electro-mechanical system (MEMS) technology, followed by experimental characterization of its performance parameters. The experimental results show that the magnetic sensitivities of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i>-MSU and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i>-MSU are 114.3 mV/T and 109.8 mV/T. The output voltages of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i>-MSU and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i>-MSU reflected cosinusoidal and sinusoidal curves respectively with the rotation of the magnetic field within the range of 0°-360°. The sensor can continuously perform multi range cyclic angle measurement and maintain stable performance. The sensor's angular monitoring resolution reaches 0.1° during a signal integration time of 0.7 s, with a nonlinearity error of 0.74% of full scale (F.S.).