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Characterizing MEMS Magneto-Impedance Sensors
Using Agilent 4294A and E4991A Impedance Analyzers
Application Note Excellent accuracy and repeatability
Easy evaluation of Magneto-
Impedance characteristics
A wide variety of design-automation
tools and functions
Figure 1. Agilent 4294A and E4991A
Impedance Analyzers
Introduction Evaluation of MI Characteristics
This application brief describes the benefits of using of the Amorphous Magnetic
Agilent impedance analyzers for device characterization
of MEMS Magneto-Impedance (MI) sensors and how they Material
improve design and test efficiency while offering a wide
variety of design-automation tools and functions. Evaluating the MI sensor's sensitivity is very important
because its sensitivity depends on the impedance change
of the amorphous magnetic material when high frequency
Agilent Impedance Analyzers is applied.
The 4294A covers the range of 40 Hz to 110 MHz and the Z
E4991A, from 1 MHz to 3 GHz. These impedance analyzers
(see Figure 1) offer excellent impedance measurement ac-
curacy and are optimum tools for both design and manufac-
turing test of MEMS MI sensors.
MEMS MI Sensor
Hex
The MI sensor applies the principle of the MI effect. The
impedance of the amorphous magnetic material changes 0
depending on the external magnetic field when high Figure 3. Impedance vs. Magnetic Field
frequency current is applied. Figure 2 shows the equation
of this characteristic. High sensitive MI sensors are easily
miniaturized into MEMS devices. For an MI sensor, the impedance is low at low frequen-
cies and changes rapidly at high frequencies (Figure 4).
The instrument's impedance accuracy with sufficient test
a frequency resolution is required to know the true perfor-
Z= Rdc (1 + j)