Methods and apparatus for reducing filter delay
AssigneeAllegro MicroSystems, LLC
InventorRoman Procházka
Life of this patent
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Abstract
A filter circuit includes a filter having an input and an output at which an output of the filter is provided, a step detector coupled to receive an input signal at the input of the filter and configured to detect a predetermined step in the input signal and to assert a bypass signal in response to detection of the predetermined step. A logic circuit is responsive to the bypass signal and configured to cause the input signal to be coupled to the output of the filter without filtering when the bypass signal is asserted.
Claims23
A filter circuit, comprising:
- a filter having an input and an output at which an output of the filter is provided;
- a step detector coupled to receive an input signal at the input of the filter and configured to detect a predetermined step in the input signal and to assert a bypass signal in response to detection of the predetermined step;
- and
- a logic circuit responsive to the bypass signal and configured to cause the input signal to be coupled to the output of the filter without filtering when the bypass signal is asserted.
A magnetic field sensor comprising:
- one or more magnetic field sensing elements configured to generate a magnetic field signal in response to a magnetic field;
- a front end amplifier coupled to the one or more magnetic field sensing elements and configured to amplify the magnetic field signal to generate a front end output signal;
- a filter circuit comprising:
- a filter having an input coupled to receive the front end output signal and an output at which a filter output signal is provided;
- a step detector coupled to receive the front end output signal and configured to detect a predetermined step in the input signal and to assert a bypass signal in response to detection of the predetermined step;
- and
- a logic circuit responsive to the bypass signal and configured to cause the front end output signal to be coupled to the output of the filter without filtering when the bypass signal is asserted;
- and
- an output circuit coupled to receive the filter output signal and having an output at which a sensor output signal is provided in response to the filter output signal.
A method comprising:
- receiving an input signal at an input of a filter;
- monitoring the input signal to detect a predetermined step change;
- and
- selectively filtering, by the filter, the input signal to generate a filter output signal when the predetermined step change in the input signal is not detected or bypassing the filter when the predetermined step change in the input signal is detected, wherein filtering comprises selectively coupling at least one sampling capacitor either to the input of the filter through a first switch or to an input of an amplifier through a second switch.
Apparatus comprising:
- a filter having an input and an output at which an output of the filter is provided;
- means, coupled to receive an input signal at the input of the filter, for detecting a predetermined step in the input signal and to assert a bypass signal in response to detection of the predetermined step;
- and
- means, responsive to the bypass signal, for coupling the input signal to the output of the filter without filtering when the bypass signal is asserted.
Dependencies are inferred from the claim text.