Method for dynamic noise reduction of magnetic field sensor signals and a magnetic field sensor circuit with dynamic noise reduction

1. A method for dynamic noise reduction of magnetic field sensor signals of a magnetic field sensor circuit with a magnetic field sensor and a switching device, the method comprising:

providing, via the magnetic field sensor, a sensor signal to a sensor signal output;

providing the switching device with a signal comparator, a low pass filter, and a multiplexer, the switching device having a signal input interconnected with the sensor signal output and a signal output, the signal comparator having a first input interconnected with the signal input and a second input interconnected with the low pass filter output and a control signal output interconnected with the multiplexer, the multiplexer having a first input interconnected with the signal input and a second input interconnected with the output of the low pass filter and an output interconnected with the signal output;

comparing the sensor signal to the output signal of the low pass filter via the signal comparator;

comparing the result to a predetermined threshold value; and

performing, provided that the result exceeds the predetermined threshold value, a switchover via the control signal of the multiplexers so that the signal output is interconnected with the sensor signal, and if the result of the comparison is less than the predetermined threshold value, a switchover is performed via the control signal of the multiplexers so that the signal output is interconnected with the output of the low pass filter.

2. The method for dynamic noise reduction according to claim 1 , wherein, via the signal comparator, the signal present at the second input of the signal comparator is subtracted from the signal present at the first input of the signal comparator and then the amount of the difference of the two signals is compared to the predetermined threshold value.

3. The method for dynamic noise reduction according to claim 1 , wherein the low pass filter is a recursive filter.

4. The method for dynamic noise reduction according to claim 1 , wherein the signal of the signal output is applied to the second input of the signal comparator via a delay element looped between the signal output and a second multiplier.

5. The method for dynamic noise reduction according to claim 1 , wherein, via a first multiplier, the input signal is multiplied by a factor of 1/d, wherein d includes all real numbers, and via a second multiplier, the delayed signal of the signal output is multiplied by a factor 1−1/d, and wherein the two signals of the first and second multipliers are summed by an adder and are applied to the second input of the multiplexer.

6. The method for dynamic noise reduction according to claim 1 , wherein the bandwidth of the low pass filter is increased, provided that an amount of a difference is above the predetermined threshold value, in order to shift a switching of the multiplexer.

7. The method for dynamic noise reduction according to claim 1 , wherein a value of the predetermined threshold value is changed.

8. The method for dynamic noise reduction according to claim 1 , wherein a linear evaluation of the result of the comparison of the signals present at the two inputs is performed.

9. A magnetic field sensor circuit with dynamic noise reduction, comprising:

a magnetic field sensor providing a sensor signal to a sensor signal output; and

a switching device, comprising a signal comparator, a low pass filter, and a multiplexer,

wherein the switching device has a signal input interconnected with the sensor signal output,

wherein the signal comparator has a first input interconnected with the signal input and a second input interconnected with the low pass filter and a control signal output interconnected with the multiplexer, and

wherein the multiplexer has a first input connected to the signal input and a second input interconnected with the output of the low pass filter and an output interconnected with the signal output,

wherein, based on a comparison carried out in the signal comparator, the output of the multiplexer is interconnected with either the signal input or the output of the low pass filter.

10. The magnetic field sensor circuit according to claim 9 , wherein, if during the comparison, the amount difference between the sensor signal and a signal of the low pass filter exceeds a predetermined threshold value, the output of the multiplexer is interconnected with the signal input, or if the amount difference is below the threshold value, the output of the multiplexer is interconnected with the output of the low pass filter.

11. The magnetic field sensor circuit according to claim 9 , wherein the low pass filter has a control input and the control input is interconnected with the control output of the signal comparator.

12. The magnetic field sensor circuit according to claim 9 , wherein the low pass filter is a recursive filter.

13. The magnetic field sensor circuit according to claim 9 , wherein the low pass filter has a first multiplier looped between the signal input and an adder and the low pass filter comprises a second multiplier looped between the adder and a delay element, and

wherein the delay element is interconnected between the second input of the signal comparator and the signal output.

14. The magnetic field sensor circuit according to claim 9 , wherein the magnetic field sensor is a Hall sensor.

15. The magnetic field sensor circuit according to claim 9 , wherein the multiplexer is a simple multiplexer.