Abstract To enhance performances and approach the detection limits of a magnetometer, it is necessary to investigate its intrinsic noise. The intrinsic noise of magnetic film/planar coil sensors has been analyzed, where the sensors consist of magnetic films and planar coils. Two architectures of magnetic film/planar coil sensors are investigated: self-inductive and mutual inductive. The pickup coil is in an open circuit during the detection, there is no resistive noise source in a mutual inductive magnetic film/planar coil sensor, and its noise is lower than that of a self-inductive one. Irrespective of any architectures, the noise of magnetic film/planar coil sensors is closely related to their electric excitations. The excitation signal generates an ac field H ac H a c inside the magnetic films. When the magnitude of the ac field H acm is less than that of the anisotropic field H K H K in the magnetic film, the noise of a mutual inductive sensor can be reduced by increasing amplitude of excitation current. Until H acm = H K H a c = H K , mutual inductive sensor obtains a minimum noise value. When H acm > H K , H a c > H K the noise of mutual inductive sensor can be reduced by reducing the amplitude of excitation current. It is observed that the noise is strongly dependent on the excitation frequency. Under the excitation current of 1.5 mA at 100 kHz, the voltage noise spectral density of a mutual inductive magnetic film/planar coil sensor has a minimum value of 47.55 nV/√Hz @ 1 Hz, and the equivalent magnetic noise is 66 nT/√Hz @ 1 Hz. The voltage noise spectral density of a self-inductive magnetic film/planar coil sensor has a minimum value of 86.26 nV/√Hz @ 1 Hz, and the equivalent magnetic noise is 452.4 nT/√Hz @ 1 Hz.

中文翻译：

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磁性薄膜/平面线圈传感器中的固有噪声

摘要 为了提高磁力计的性能并接近其检测极限，有必要对其固有噪声进行研究。分析了磁性薄膜/平面线圈传感器的固有噪声，其中传感器由磁性薄膜和平面线圈组成。研究了磁性薄膜/平面线圈传感器的两种架构：自感和互感。检测时拾波线圈处于开路状态，互感磁膜/平面线圈传感器无阻性噪声源，噪声低于自感式。无论采用何种架构，磁性薄膜/平面线圈传感器的噪声与其电激励密切相关。激励信号在磁膜内部产生交流场H ac H ac 。当交流场H acm 的幅值小于磁膜中各向异性场HKHK的幅值时，可以通过增大励磁电流的幅值来降低互感传感器的噪声。直到 H acm = HKH ac = HK ，互感传感器获得最小噪声值。当H acm > HK , H ac > HK 时，可以通过减小励磁电流的幅值来降低互感传感器的噪声。据观察，噪声强烈依赖于激励频率。在100 kHz 1.5 mA激励电流下，互感磁膜/平面线圈传感器的电压噪声谱密度最小值为47.55 nV/√Hz@1 Hz，等效磁噪声为66 nT/√赫兹@1赫兹。