Texas Instruments Corporation

Stichting Voor De Technische Wetenschappen

Sayyed Mahdi Kashmiri

Kofi A A Makinwa

Willem Johannes Kindt

A fluxgate sensor including a magnetic-to-digital converter (MDC) can be adapted to measure an external magnetic field Bwith a bandwidth f. The MDC forward path can include: (a) converting an analog sense signal from the fluxgate sense coil to corresponding oversampled digital data using an oversampling data converter with an oversampling frequency fgreater than f; and (b) loop filtering the oversampled digital data, synchronous with the oversampling frequency f, to generate the loop output digital data. The MDC feedback path can include: (a) generating the feedback compensation current Ifrom the loop output digital data, synchronous with a feedback path frequency fequal to ((M/N)&#xd7;f), where, M and N are integers; and (b) injecting the feedback compensation current Iinto the fluxgate compensation coil to induce the compensation field B, such that the induced compensation field Bnulls the external field B.

Fluxgate magnetic-to-digital converter with oversampling closed loop

An electrothermal frequency-locked loop (EFLL) circuit is described. This EFLL circuit includes an oscillator in a feedback loop. A drive circuit in the EFLL circuit generates a first signal having a fundamental frequency, and an electrothermal filter (ETF) in the EFLL circuit provides a second signal based on the first signal. This second signal has the fundamental frequency and a phase (relative to the first signal) that corresponds to a temperature-dependent time constant of the ETF. Moreover, a sensing component in the EFLL circuit determines a parameter associated with a temperature of the ETF. For example, the parameter may be the temperature or may be other than the temperature, such as the fundamental frequency and/or the phase of the second signal. Furthermore, the EFLL circuit includes a compensation circuit that compensates for frequency changes associated with changes in the temperature based at least on the parameter so that the fundamental frequency is approximately independent of the temperature.

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Sayyed Mahdi Kashmiri