Allegro Microsystems, LLC

Craig S Petrie

Bryan Cadugan

Soo-Chang Choe

Michael C Doogue

David Jamie Haas

Alexander Latham

Aaron Cook

Virag V Chaware

William P Taylor

Hernán D Romero

Nevenka Kozomora

Cory Voisine

Steven Daubert

Mark J Donovan

Jesse Lapomardo

David Toebes

Dominik Geisler

Roman Prochazka

Srujan Shivanakere

Richard Stary

Milan Valenta

Sina Haji Alizad

Akshay Pai

Matthew Regan

Arun Prasad Javvaji

A method for use in a magnetic field sensor, including: in each of a plurality of calibration periods, generating a reference magnetic field based on a different one of a plurality of drive codes; storing, in a memory, a plurality of values of a reference magnetic field signal that is generated in response to the reference magnetic field, each of the values of the reference magnetic field signal being generated by sampling the reference magnetic field signal in a different one of the plurality of calibration periods; calculating a calibration gain coefficient based on the plurality of values of the reference magnetic field signal; and storing the calibration gain coefficient in the memory and using the calibration gain coefficient to adjust an output of the magnetic field sensor.

Diagnostic path for gain and offset calibration

A magnetic field sensor includes a current source configured to generate a bias current, a plurality of magnetic field transducers, each having power terminals coupled to the current source and output terminals at which an output signal of the transducer is provided, wherein the power terminals of each of the plurality of magnetic field transducers are electrically coupled together in series so that the bias current flows through each of the plurality of magnetic field transducers in series. A capacitively-coupled summing amplifier has a plurality of inputs, each configured to receive the output signal of a respective one of the plurality of magnetic field transducers, and an output at which an amplified and summed signal is provided, wherein the capacitively-coupled summing amplifier is configured to amplify and sum the received output signals of the plurality of magnetic field transducers.

Magnetic field sensor with stacked transducers and capacitive summing amplifier

A current sensor integrated circuit to sense a current through a resistor includes a substrate, a tub disposed in the substrate, an analog front end disposed in the tub and comprising an amplifier having inputs coupled across the resistor and a charging circuit configured to bias the analog front end and the tub to a bias voltage that is a predetermined offset voltage greater than a common mode voltage associated with the resistor. In embodiments, the analog front end is biased to a first bias voltage and the tub is biased to a second, different bias voltage.

Current sensor integrated circuit with common mode voltage rejection

An isolation circuit that isolates a driver circuit that is biased at a first common mode voltage from a detection circuit that is biased at a second common mode voltage using isolation capacitors. The detection circuit includes a transimpedance amplifier having improved susceptibility to transient common-mode input signals and improved insensitivity to parasitic capacitance on the isolation capacitor terminals. Included within the transimpedance amplifier are circuits for mirroring current to convert the input current from the isolation capacitors into a voltage value and to amplify that voltage value. The transimpedance amplifier outputs a differential voltage value that is held by a latch circuit so that a comparator in the detection circuit can process the differential voltage value and output a differential signal with fully restored logic levels.

Digital capacitive isolator

A magnetic field sensor for sensing external magnetic fields on multiple axes comprises a coil structure and a gain equalization circuit. The coil structure generates reference fields on magnetic field sensing elements in each axis. The gain equalization circuit measures and compares reference fields to generate gain-equalized output signals responsive to the external magnetic fields.

Gain equalization for multiple axis magnetic field sensing

A sensor includes an analog front end having a circuit element responsive to a clock signal and a clock generating circuit configured to generate the clock signal having blanking time periods during which the clock signal is held at a constant level, wherein the circuit element is not operational during the blanking time periods. The blanking time periods correspond to time periods during which transitions of a common mode input voltage to the sensor are expected to occur.

Signal path blanking during common mode input transitions

A sensor integrated circuit includes a main processing channel that responds to an input signal by generating a first processed signal from the input signal. Also included is a diagnostic processing channel that responds to the input signal by generating a second processed signal from the input signal. The main processing channel has a first response to disturbances and the diagnostic processing channel has a second response to disturbances that is slower than the first response of the main processing channel. A checker circuit in the sensor integrated circuit detects faults in the sensor IC and generates a fault signal when the first processed signal and the second processed signal differ from each other by more than a threshold amount.

Systems and methods for comparing signal channels having different common mode transient immunity

Systems and methods described herein provide a current sensor having fault detection circuitry configured to detect over-current and/or current faults corresponding to current through a conductor being greater than a predetermined level. The current sensor can include a shared signal path, a main signal path, and a fault detection signal path to perform both fault detection and current detection signal processing. The current sensor can include one or more magnetic field sensing elements configured to generate a magnetic field signal indicative of the current through the conductor, an analog-to-digital converter (ADC) configured to receive the magnetic field signal and convert the magnetic field signal into a digital signal, and a fault detector responsive to the digital signal to generate a fault signal indicative of the current through the conductor being greater than a predetermined level.

Current fault detection systems and methods for a current sensor

A buffer amplifier comprises a source follower and a feedback amplifier. The feedback amplifier may be configured to control a drain current of the source follower to remain substantially constant independent of a load.

Voltage buffer for input voltages above a supply voltage or below ground voltage

An apparatus comprises a first measurement circuit having a first magnetic field sensing element to detect a measured magnetic field and produce a first signal representing the measured magnetic field, and a first signal processing circuit to process the first signal to produce a first processed signal. A second measurement circuit comprises a second magnetic field sensing element to detect a measured magnetic field and produce a second signal representing the measured magnetic field, and a second signal processing circuit to process the second signal to produce a second processed signal. A diagnostic processing circuit is coupled to receive the first signal and the second signal and configured to process the first signal during a first time period to produce a first diagnostic signal, and process the second signal during a second time period. A logic circuit determines if an error is present.

Efficient signal path diagnostics for safety devices

A magnetic field sensor comprises at least one magnetic field sensing element configured to generate a measured magnetic field signal responsive to an external magnetic field; a diagnostic circuit configured to generate a diagnostic signal, wherein the diagnostic signal is not dependent on a measured magnetic field; a signal path comprising an amplifier and an analog-to-digital converter for processing the measured magnetic field signal to generate a sensor output signal indicative of the external magnetic field during a measured time period and for processing the diagnostic signal during a diagnostic time period; and a switch coupled to receive the measured magnetic field signal and the diagnostic signal and direct the measured magnetic field signal to the signal path during the measured time period and direct the diagnostic signal to the signal path during the diagnostic time period.

Magnetic field sensor with shared path amplifier and analog-to-digital-converter

Methods and apparatus for processing a signal comprise at least one circuit configured to generate a measured signal during a measured time period and a reference signal during a reference time period. Also included is at least one dual- or multi-path analog-to-digital converter comprising at least a first processing circuit configured to process the measured signal, at least a second processing circuit configured to process the reference signal, and a third processing circuit configured to process both the measured signal and the reference signal.

A filter with dynamic parameter generation may comprises an input to receive an unfiltered signal, an output to provide a filtered signal, a filtering circuit that filters the unfiltered signal to produce the filtered signal according to a transfer function having at least one dynamic parameter, and a dynamic parameter generator circuit. The dynamic parameter generator circuit comprises an input to receive the unfiltered signal, a signal processing circuit to estimate a level of dynamics of the unfiltered signal, a parameter generation circuit to generate the at least one dynamic parameter based on the estimated level of dynamics of the unfiltered signal, and an output to provide the at least one dynamic parameter.

Filter circuit with dynamic parameter generation

A ground fault detection circuit is configured to detect a ground fault in a circuit or system that has more than one ground reference. In an embodiment, an electronic circuit includes a first circuit coupled to a first ground node. The first ground node is coupled to a first ground reference. The electronic circuit also includes a second circuit coupled to a second ground node. The second ground node is coupled to a second ground reference. The ground fault detection circuit is configured to detect an open circuit between the first ground node and the first ground reference or between the second ground node and the second ground reference by comparing a voltage at the first ground node to a voltage at the second ground reference or comparing a voltage at the second ground node to a voltage at the first ground reference.

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Merrimack, NH, United States of America

Craig S Petrie