Magnetic impedance sensor

A magnetic impedance sensor comprising:

• a pulse oscillator configured to apply an electrical pulse current to a magneto-impedance element;
• the magneto-impedance element configured to generate an alternate current voltage corresponding to a magnetic field intensity around the magneto-impedance element;
• and
• signal processing circuitry configured to signal process the alternate current voltage corresponding to the magnetic field intensity around the magneto-impedance element generated by the magneto-impedance element and output the signal processed alternate current voltage, wherein
• an alternate current voltage corresponding to the external magnetic field intensity around the magneto-impedance element is generated by applying the electrical pulse current to the magneto-impedance element,
• the magneto-impedance element is configured to measure the external magnetic field intensity around said magneto-impedance element as the generated alternate current voltage,
• the electrical pulse current comprises a basic pulse current for generating the alternate current voltage corresponding to the external magnetic field around the magneto-impedance element and a compensating pulse current having opposite polarity to the basic pulse current, the compensating pulse current being for compensating for linear characteristic of the magnetic impedance sensor to linearly change output voltage in response to a change of the external magnetic field intensity,
• the pulse oscillator is configured to apply the basic pulse current and the compensating pulse current alternately to the magneto-impedance element, and a magnetization of the magneto-impedance element in a circumferential direction is alternately reversed between positive and negative magnetized states across a zero-magnetized state where the magnetization of the magneto-impedance element in the circumferential direction is zero by shifting the magnetization of the magneto-impedance element to an opposite polarity direction always after passing or going through the zero-magnetized state in order to avoid the zero-magnetized state of the magneto-impedance element in the circumferential direction, and
• an absolute value of the compensating pulse current is set by the pulse oscillator to be within a range, the range being a rate of 0.1%-10% smaller than an absolute value of the basic pulse current.