Highly sensitive high frequency carrier type thin film sensor

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We propose herein a method by which to measure the phase of the carrier in a high frequency carrier-type sensor (GMI sensor). The proposed method is based on a carrier suppression technique. The phase of the carrier signal changed dramatically by approximately 180 degrees around the carrier suppression when a small dc field was applied. The phase sensitivity for a small DC field reached 3600 degrees/Oe. In addition we investigate the relationship between phase sensitivity and suppressed carrier level in the suppression circuit, the measured data nearly corresponded to theoretical data. We have fabricated a sensor system which is composed of sensor element and Dual Mixer Time Difference (DMTD) method to detect a change of phase difference as a function of small magnetic field. Sensor element was fabricated as a meander pattern, and the phase difference was about 5 degrees/Oe. The jitter level was decreased about 5.5x10^<-4> degrees when the sample rate was 1 kHz. The resolution of magnetic field detection was obtained about 3.3x10^<-6> Oe/Hz^<1/2>.