Sensor Signal Offset Reduction via Modulation and Demodulation
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Solution Overview
Problem
Existing methods for reducing sensor signal offsets, such as spinning current technology and chopper methods, primarily focus on compensating for amplifier offsets, leaving residual offsets from the sensor source unaffected, which limits measurement precision and resolution, especially in Hall sensors where single phase offsets dominate the signal.
Innovation Solution
A method that modulates sensor signals before amplification, weighting phases with opposite signs and subtracting mean offsets, followed by demodulation, to reduce the total offset across the signal processing chain, allowing for improved amplification and higher resolution in analog/digital conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If amplification is increased to improve signal resolution, then measurement precision improves, but the amplifier offset causes the control range to be exceeded and overload occurs
Solution Approach 1:
The patent applies preliminary anti-action by subtracting the amplifier offset (determined during calibration) from the sensor signal before amplification. This pre-compensation ensures that the offset does not cause overload during subsequent amplification, allowing the amplifier to operate within its control range while achieving higher gain for improved measurement precision.
Solution Approach 2:
The patent performs offset determination and subtraction as a preliminary action during a calibration phase before actual measurement. By determining the amplifier offset in advance and subtracting it from subsequent measurements, the system prepares the signal path to handle high-gain amplification without overload, thereby enabling improved signal resolution.
Data Source
AI summary
In a method and a sensor arrangement for processing sensor signals of a sensor, which is operated in a plurality of measurement cycles with successive phases with different driving, before the amplification, the sensor signals of n phases of each measurement cycle are weighted with negative mathematical sign and the sensor signals of the remaining n phases of the measurement cycle are weighted with positive mathematical sign by a modulation. Before the amplification, an offset averaged from the sensor signals of the two phases is subtracted from the sensor signals of each two of the phases which were weighted with different mathematical sign and have an offset of the same mathematical sign after the modulation. The artificially generated offset is eliminated again by a demodulation after the amplifier and a summation over the digitized signals of each measurement cycle.