Sensor with signal amplitude adaptive hysteresis
First Claim
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1. An apparatus configured to detect transitions between, first and second relative states of a transducer responsive to an excitation stimulus configured to provide a transducer output having an amplitude envelope that modulates in accordance with the operating region of the excitation stimulus comprising:
- a comparator circuit having at least two inputs and at least one output for providing a two state output signal wherein state changes of the output signal correspond to state changes of the transducer;
a reference circuit configured to provide a reference signal to one of the pair of inputs of the comparator circuit;
a transducer circuit configured to provide a transducer signal proportional to the transducer output to the other of the pair of inputs of the comparator circuit; and
, a hysteresis circuit configured to provide a hysteretic deadband proportional to the amplitude envelope of the transducer output to the response of the comparator circuit to the reference and transducer signals.
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Abstract
In a magnetoresistive sensor employing a single stage comparator circuit for signal threshold detection, an hysteresis deadband is established substantially proportional to signal amplitude. The sensor includes a transducer comprising at least one magnetoresistive element and an hysteresis circuit also including the at least one magnetoresistive element.
22 Citations
15 Claims
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1. An apparatus configured to detect transitions between, first and second relative states of a transducer responsive to an excitation stimulus configured to provide a transducer output having an amplitude envelope that modulates in accordance with the operating region of the excitation stimulus comprising:
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a comparator circuit having at least two inputs and at least one output for providing a two state output signal wherein state changes of the output signal correspond to state changes of the transducer;
a reference circuit configured to provide a reference signal to one of the pair of inputs of the comparator circuit;
a transducer circuit configured to provide a transducer signal proportional to the transducer output to the other of the pair of inputs of the comparator circuit; and
,a hysteresis circuit configured to provide a hysteretic deadband proportional to the amplitude envelope of the transducer output to the response of the comparator circuit to the reference and transducer signals. - View Dependent Claims (2, 3, 4)
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5. An apparatus for detecting transitions between first and second relative resistance states of a magnetoresistive transducer responsive to local magnetic flux density configured to provide a transducer output voltage having an amplitude envelope that modulates in accordance with the operating region of the magnetic flux density, comprising:
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a comparator circuit having respective inverting and non-inverting inputs, and an output providing a comparator output voltage wherein state changes of the comparator output voltage correspond to relative resistance state changes of the magnetoresistive transducer;
a reference circuit configured to provide a reference voltage signal to one of inputs of the comparator circuit;
a transducer circuit configured to provide a transducer voltage signal proportional to the transducer output voltage to the other of the inputs of the comparator circuit; and
a hysteresis circuit configured to provide a hysteretic deadband proportional to the amplitude envelope of the transducer output voltage to the response of the comparator circuit to the reference and transducer voltage signals. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A sensing circuit, comprising:
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a. least one MR sensor outputting signals defining an amplitude envelope;
at least one comparator electrically connected to the MR sensor, at least one reference circuit providing a reference signal to the comparator; and
at least one hysteresis circuit providing a hysteretic deadband that adapts to a triggering signal, the MR sensor establishing a portion of the hysteresis circuit.
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Specification