Improvement of the off-diagonal magnetoimpedance sensor white noise

This work deals with the analysis of noise sources of the off-diagonal magneto-impedance sensor with stressannealed amorphous ribbon. This experimental analysis shows that the equivalent magnetic noise spectral density is mostly due to the electronic conditioning circuitry that operates the sensor. The electronic noise was then reduced with employment of an improved excitation-detection technique for our sensor and an equivalent magnetic noise spectral density below 1 pT/ √ Hz in white noise region has been reached. Indeed, the equivalent magnetic white noise level of the output signal decreased from 5 pT/ √ Hz to 560 fT/ √ Hz. Nevertheless, this noise level is still limited by the electronic conditioning, leaving room for further improvement.