Patent ID: 6448767
Filing Date: 2002-09-10
Classification: G01R

Abstract:
A flux locked loop coupled to at least one external electric or magnetic sensor, the external electric or magnetic sensor exhibiting a double side band suppressed carrier characteristic, the flux locked loop being operable to receive at least one input signal from and provide feedback to the external electric or magnetic sensor, the input signal comprising a desired signal and at least one undesired signal, the flux locked loop comprising:at least one bias current source operable to produce bias current for injection into the external electric or magnetic sensor; a first amplifier operable to impedance match and to amplify the input signal received from the external electric or magnetic sensor; a flux modulation source operable to produce a flux modulation signal having a waveform and a flux modulation frequency and a phase and an amplitude; a bandpass filter operable to remove from the input signal at least one of the undesired signals; a mixer operable to provide synchronous demodulation of the input signal; an integrator operable to perform integration and differentiation on the input signal; and a matching combiner circuit operable to impedance match and combine the input signal with the flux modulation signal.