Abstract:
A compensation coil placed at least partially underneath a magnetic field sensor package in an electronic system provides attenuation of electromagnetic interference (EMI). In an embodiment, the compensation coil attenuates EMI in a frequency band which overlaps with an operating frequency band of the magnetic field sensor. This allows the magnetic field sensor to make accurate magnetic field measurements in the presence of system level alternating current (AC) EMI. In an embodiment, a system comprises: a magnetic field sensor; a compensation coil placed at least partially underneath the magnetic field sensor; and a reverse current generator coupled to the compensation coil and to a power supply that is coupled to an electromagnetic interference (EMI) source, the reverse current generator operable to generate a reverse current in the compensation coil to generate a counter magnetic field for compensating the EMI.
Abstract:
An array of resistive sensor circuits may be used to gather sensor data. Each resistive sensor circuit may have a resistive sensor and an associated switch. Row decoder circuitry may supply rows of the sensor circuits with control signals on row lines. Capacitors associated with respective columns of the array may be provided with an initialization voltage. The control signals on the row lines may be used to turn on the switches in a selected row of the resistive sensor circuits and thereby discharge the capacitors through the resistive sensors of that row. Comparators may have first inputs coupled to the capacitors and second inputs that receive a reference voltage. A column readout circuit may have memory and processing circuitry that receives count values from a counter and that stores the count values in response to toggling output signals from the comparators.
Abstract:
An electronic device may be provided with an electronic compass. The electronic compass may include magnetic sensors. The magnetic sensors may include thin-film magnetic sensor elements such as giant magnetoresistance sensor elements. Magnetic flux concentrators may be used to guide magnetic fields through the sensor elements. To reduce offset in the electronic compass, the magnetic flux concentrators may be demagnetized by applying a current to a coil in the housing. The coil may be formed from loops of metal traces within a printed circuit or other loops of conductive paths. Magnetic flux concentrators may have ring shapes. A ring-shaped magnetic flux concentrator may be formed from multiple thin stacked layers of soft magnetic material separated by non-magnetic material.
Abstract:
Systems, methods, and computer-readable media for calibrating the offset of a magnetometer assembly with reduced power are provided. In one embodiment, a method for operating an assembly may include determining a difference between a current signal measurement output component of a first magnetometer sensor and a previous signal measurement output component of the first magnetometer sensor, comparing the determined difference with a current threshold value, and generating an assembly output based on the comparing, where, when the determined difference is greater than the current threshold value, the generating may include providing a first assembly output using a current offset output component of a second magnetometer sensor, and, when the determined difference is less than the current threshold value, the generating may include providing a second assembly output using a previous offset output component of the second magnetometer sensor.
Abstract:
A device operates in pairing mode, indoor navigation mode or search mode. For each mode, a magnetic sensor in the device senses one or more alternating current (AC) magnetic fields emitted by one or more transmitters in a three-dimensional (3D) space, and uses the one or more AC magnetic fields to determine a position of the device relative to the one or more transmitters or another device. In pairing mode, relative position vectors computed from two or more AC magnetic fields allows the device to choose the closest transmitter for pairing. In indoor navigation mode, multiple detections of AC magnetic fields emitted by multiple transmitters assist a user in navigating an indoor space. In search mode, a companion device and a lost device each sense an AC magnetic field from a transmitter, and the AC magnetic fields are used to determine a relative position vector from the companion device to the lost device.
Abstract:
Systems, methods and non-transitory, computer-readable mediums are disclosed for a magnetic field sensor array with electromagnetic interference cancellation. In an embodiment, a circuit comprises: a first circuit configured for obtaining an output signal from a magnetic field sensor array in an electronic system, the output signal representing a magnetic field present in the electronic system, the magnetic field including electromagnetic interference (EMI) generated by one or more magnetic aggressors of the electronic system; and a second circuit configured to apply one or more magnetic field gradient heat maps to the output signal.
Abstract:
Systems, methods, apparatuses and non-transitory computer-readable mediums are disclosed for a self-calibrating system architecture for magnetic distortion compensation. In an embodiment, an electronic system comprises: a magnetometer; a plurality of spaced-apart calibration coils proximate to the magnetometer; first circuitry configured to excite the calibration coils during a calibration phase of the electronic system; second circuitry configured to measure a first magnetic field vector in a vicinity of the magnetometer that is generated by the excited calibration coils; third circuitry configured to: generate sensitivity values based on the first magnetic field vector measurement and a baseline magnetic field vector; and a storage device configured for storing the sensitivity values.
Abstract:
A compensation coil placed at least partially underneath a magnetic field sensor package in an electronic system provides attenuation of electromagnetic interference (EMI). In an embodiment, the compensation coil attenuates EMI in a frequency band which overlaps with an operating frequency band of the magnetic field sensor. This allows the magnetic field sensor to make accurate magnetic field measurements in the presence of system level alternating current (AC) EMI. In an embodiment, a system comprises: a magnetic field sensor; a compensation coil placed at least partially underneath the magnetic field sensor; and a reverse current generator coupled to the compensation coil and to a power supply that is coupled to an electromagnetic interference (EMI) source, the reverse current generator operable to generate a reverse current in the compensation coil to generate a counter magnetic field for compensating the EMI.
Abstract:
A high dynamic range magnetometer architecture and method are disclosed. In an embodiment, a magnetometer sensor comprises: a variable magnetic gain stage including a plurality of selectable signal gain paths, each signal gain path including a magnetic sensor and a magnetic flux concentrator, and for each signal gain path the magnetic flux concentrator being positioned a different distance from the magnetic flux concentrator to provide a different magnetic gain for the signal gain path; a variable magnetic sensing stage coupled to the variable magnetic gain stage, the variable magnetic sensing stage operable to provide variable magnetic sensing to each signal gain path; and a gain control stage coupled to the variable magnetic sensing stage, the gain control stage operable to select one of the signal gain paths and to provide signal conditioning to the selected signal gain path.
Abstract:
Embodiments are disclosed for various configurations of a hybrid Hall/MR magnetometer with self-calibration. In an embodiment, a method comprises: a circuit coupled to a magnetometer and configured to determine whether the magnetometer is to operate in a sensing operation mode or a self-calibration operation mode. The magnetometer comprises a Hall sensor and MR sensor coupled to the circuit. In accordance with determining a sensing operation mode, the Hall sensor is turned and the MR sensor is turned on; and an external magnetic field is measured using the MR sensor. The magnetic field measurement is calibrated using a MR sensor bias error determined in a self-calibration operation mode of the sensor.