# A Three-Axis Magnetic Field Microsensor Fabricated Utilizing a CMOS Process
## 4 Results  
The MF microsensor characteristics were measured using a magnetic testing system. The system contained an MF detector, a magnetic field generator, and an oscilloscope. The function of a magnetic generator produced an MF supplied to the microsensor. The MF detector calibrated the magnitude of the MF generated by magnetic generator. The MF microsensor output signal was measured with an oscilloscope. To characterize the MF microsensor with amplifier circuitry, its performances were tested. The MF microsensor was set in the magnetic testing system. A 4 mA current and a 1.8 V voltage were applied to the microsensor. The magnetic field generator supplied an MF range of \(-\)200-200 mT to the microsensor, and MF intensity was detected utilizing the MF detector. First, a magnetic field in the \(x\)-direction was applied to the microsensor. The oscilloscope was used to measure the output voltage of the microsensor. The sensing response of the microsensor in the \(x\)-direction MF was recorded. Figure 11 illustrates the measured output voltage versus the applied magnetic field in the \(x\)-direction. As depicted in Figure 11, the microsensor output voltage was \(-\)0.17 mV at \(-\)100 mT and 0.171 at 100 mT. The results depicted that the microsensor output voltage varied from \(-\)0.289 at \(-\)100 mT to 0.29 mV at 200 mT. The slope of the curve in Figure 11 was about 1.45 V/T, which was the measured sensitivity of the MF microsensor with amplifier circuitry in the \(x\)-direction MF. The microsensor power consumption was 7.2 mW. To understand the sensing performance of the microsensor with amplifier circuitry in the \(y\)-direction MF, the microsensor was tested with the same approach. The magnetic field was applied to the microsensor in the \(y\)-direction, and the microsensor output voltage was measured with an oscilloscope. The sensing response of the microsensor in the \(y\)-direction MF was measured. Figure 12 illustrates the measured output voltage versus the applied magnetic field in the \(y\)-direction. As presented in Figure 12, the microsensor output voltage was \(-\)0.16 mV at \(-\)100 mT and 0.161 at 100 mT. The microsensor output voltage changed from \(-\)0.277 at \(-\)200 mT to 0.271 mV at 200 mT. Therefore, the measured sensitivity of the microsensor with amplifier circuitry in the \(y\)-direction MF was 1.37 V/T. Figure 10: The MF microsensor image: (**a**) chip; (**b**) magnification; (**c**) packaging. The characteristics of the microsensor with amplifier circuitry in the \(z\)-direction MF was also tested. The magnetic field was supplied to the microsensor in the \(z\)-direction, and the oscilloscope was used to record the microsensor output voltage. The sensing response of the microsensor in the \(z\)-direction MF was recorded. Figure 13 depicts measured output voltage versus applied magnetic field in the \(z\)-direction. As illustrated in Figure 13, the microsensor output voltage was \(-0.017\) mV at \(-100\) mT and \(0.016\) mV at \(100\) mT. The microsensor output voltage varied from \(-0.035\) at \(-200\) mT to \(0.03\) mV at \(200\) mT. Therefore, the measured sensitivity of the microsensor with amplifier circuitry in the \(z\)-direction MF was \(0.163\) V/T. As depicted in Figure 8, the evaluated sensitivity of the microsensor in the \(x\)-direction MF was \(1.65\) V/T. The measurement results in Figure 11 indicate that the measured sensitivity of the microsensor in the \(x\)-direction MF was \(1.45\) V/T. Comparing evaluation and measurement, the sensitivity of the microsensor in the \(x\)-direction MF has an error percentage of \(12\%\). The microsensor structure is a symmetric, so the characteristic of the microsensor in the \(x\)- and \(y\)-directions MF should the same. In fact, the measurement results in Figure 12 revealed that the microsensor sensitivity in the \(y\)-direction MF was \(1.37\) V/T. The microsensor sensitivity in the \(x\)- and \(y\)-directions MF has little difference, resulting from the deviation of fabrication and packaging.