US 6,674,279 B2Granted

Variable attenuation circuit for a differential variable reluctance sensor with enhanced initial threshold accuracy

AssigneeDelphi Technologies, Inc.

InventorsGregory J. Manlove, Kevin M. Gertiser, James C. Bach, Gerald A Kilgour

Life of this patent

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Abstract

A variable reluctance sensor interface module having a variable attenuation circuit and a rectifier and differential to single-ended conversion circuit for operating in a current mode to attenuate a differential input voltage. The variable attenuation circuit receives an input differential voltage from a magnetic sensor, converts the differential voltage to current, and variably attenuates the current. The rectifier and differential to single-ended conversion circuit converts the variably attenuated current to a voltage output. The input circuit includes an RC filter that attenuates high frequency signals. An initial threshold circuit generates an initial threshold voltage that compensates for internal resistance variations.

Claims12

Dependent claims

A variable attenuation circuit for adaptively attenuating an alternating differential voltage produced from a magnetic sensor in response to rotation of a wheel, comprising:

an input circuit for receiving an input alternating differential voltage from a magnetic sensor via first and second input lines, said input circuit including an RC filter coupled to said first and second input lines for attenuating high frequency signals;
a voltage to current converter circuit for converting the input alternating differential voltage to a differential current signal, wherein the voltage to current converter circuit has an input coupled to the input circuit, and the input has a constant input impedance;
variable attenuation circuitry for selectively attenuating said differential current signal;
a current to voltage converter circuit for converting the attenuated differential current to a voltage signal;
a comparator for comparing the voltage signal to a threshold:
an initial threshold circuit for setting an initial threshold for a comparison by the comparator, wherein the initial threshold circuit generates an initial threshold that varies proportional to internal resistance of the current to voltage converter circuit;
a controller for controlling when the initial threshold voltage will be applied as an input to the comparator;
and
an output for providing the output voltage within a preferred voltage range.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/142,095Filed 9 May 2002
Published: US 2003/0210035 A113 Nov 2003
Granted: 6 Jan 2004
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G01D 5/2013
By influencing the self-induction of one or more coils: by a movable ferromagnetic element, e.g. a core
G01D 3/02
Indicating or recording apparatus with provision for the special purposes referred to in the subgroups: with provision for altering or correcting…
G01P 3/487
Of pulse signals: delivered by rotating magnets
G01P 3/488
Of pulse signals: delivered by variable reluctance detectors