This thesis is about the development of a novel micromachined magnetic field sensor. A linear response to a wide range of magnetic fields makes this design suitable for applications rvhere large flelds need to be measured with high resolution. The operation of this sensor is based on a shift of the resonant frequency of a resonating microstructule in plesence of a magnetic field. The flexural beams of the micromachined resonator are designed so that an axial force is exerted on them when exposed to a magnetic field. The axial force will cause a positive or negative shift in the resonant frequency of the structure, depending on the directions of the magnetic field and a DC current that flows in the crossbars of the sensor. The design of the sensor allows for its fabrication in many standard MEN4S processes) and therefore sensor prototypes can be quickly and inexpensively fabricated and transfered to mass production.

A comprehensive model of the sensol is delived which encompasses the interaction of the mechanicai operation of the device and its magneto- and electrostatic response. This model is verified using finite element simulations and confirmed with experiments on four diffelent sensor geometries. Three different process flow are employed to fabricate the sensors. The pros anci cons of each of the process flows are pointed out. Custom signal plocessing electronics are designed and used to analyze the sensor data. The noise behavior of each sensor is investigated, the minimum detectable signal dete¡mined, and the best configuration selected.

The measured resolution of the sensols is about 80μT if they are used with the designed signal processing electronics. The theoretical rninimum detectable signal witlr current devices is on the order of 200nT. N4ethods to improve the noise performance of the current sensors are suggested as well as fabrication and signal processing techniques that allow for device designs with better sensitivities.