Abstract: A system comprises first and second Hall-effect sensors and an amplifier. The first Hall-effect sensor has a first bias current direction parallel to a first direction, a pair of first bias input terminals spaced along the first direction, and a pair of first sense output terminals spaced along an orthogonal second direction. The second Hall-effect sensor has a second bias current direction parallel to the second direction, a pair of second bias input terminals spaced along the second direction, and a pair of second sense output terminals connected out of phase with the first sense terminals. The amplifier has a pair of amplifier input terminals coupled to the first and second sense terminals.

Abstract: An amplifier includes a graphene Hall sensor (GHS). The GHS includes a graphene layer formed above a substrate, a dielectric structure formed above a channel portion of the graphene layer, and a conductive gate structure formed above at least a portion of the dielectric structure above the channel portion of the graphene layer for applying a gate voltage. The GHS also includes first and second conductive excitation contact structures coupled with corresponding first and second excitation portions of the graphene layer for applying at least one of the following to the channel portion of the graphene layer: a bias voltage; and a bias current. The GHS further includes first and second conductive sense contact structures coupled with corresponding first and second sense portions of the graphene layer. The amplifier also includes a current sense amplifier (CSA) coupled to the GHS. The CSA senses current output from the GHS.

Abstract: A system comprises first and second Hall-effect sensors and an amplifier. The first Hall-effect sensor has a first bias current direction parallel to a first direction, a pair of first bias input terminals spaced along the first direction, and a pair of first sense output terminals spaced along an orthogonal second direction. The second Hall-effect sensor has a second bias current direction parallel to the second direction, a pair of second bias input terminals spaced along the second direction, and a pair of second sense output terminals connected out of phase with the first sense terminals. The amplifier has a pair of amplifier input terminals coupled to the first and second sense terminals.

Abstract: A Hall sensor circuit includes a first Hall sensor, a second Hall sensor, a first preamplifier circuit, a second preamplifier circuit, a subtractor circuit, and a duty cycling circuit. The first preamplifier circuit includes an input and an output. The input is coupled to the first Hall sensor. The second preamplifier circuit includes a first input, a second input, and an output. The first input is coupled to the second Hall sensor. The subtractor circuit includes a first input coupled to the output of the first preamplifier circuit, a second input coupled to the output of the second preamplifier circuit, and an output coupled to the second input of the second preamplifier circuit. The duty cycling circuit is coupled to the second preamplifier circuit and the second Hall sensor.

Abstract: A Hall sensor circuit includes a first Hall sensor, a second Hall sensor, a first preamplifier circuit, a second preamplifier circuit, a subtractor circuit, and a duty cycling circuit. The first preamplifier circuit includes an input and an output. The input is coupled to the first Hall sensor. The second preamplifier circuit includes a first input, a second input, and an output. The first input is coupled to the second Hall sensor. The subtractor circuit includes a first input coupled to the output of the first preamplifier circuit, a second input coupled to the output of the second preamplifier circuit, and an output coupled to the second input of the second preamplifier circuit. The duty cycling circuit is coupled to the second preamplifier circuit and the second Hall sensor.

Abstract: A system includes a first amplifier and a first Hall sensor group coupled to the first amplifier. The system includes a second amplifier and a second Hall sensor group coupled to the second amplifier, where the second Hall sensor group includes a spinning Hall group. The system includes a first demodulator, where the first demodulator input is coupled to the first amplifier output. The system includes a second demodulator, where the second demodulator input is coupled to the second amplifier output. The system also includes a subtractor, the first subtractor input coupled to the first demodulator output, and the second subtractor input coupled to the second demodulator output. The system includes a filter coupled to the subtractor output and to a second input of the first amplifier, and a calibration module coupled to the subtractor output.

Abstract: A microelectronic device includes a gated graphene component over a semiconductor material. The gated graphene component includes a graphitic layer having at least one layer of graphene. The graphitic layer has a channel region, a first connection and a second connection make electrical connections to the graphitic layer adjacent to the channel region. The graphitic layer is isolated from the semiconductor material. A backgate region having a first conductivity type is disposed in the semiconductor material under the channel region. A first contact field region and a second contact field region are disposed in the semiconductor material under the first connection and the second connection, respectively. At least one of the first contact field region and the second contact field region has a second, opposite, conductivity type. A method of forming the gated graphene component in the microelectronic device with a transistor is disclosed.

Abstract: A first amplifier has an input to receive a Hall-signal output current from a first Hall element and has an output to output feedback current in response to the received Hall-signal output current. The Hall-signal output current is impeded by an impedance of the first Hall element. The feedback current is coupled to counterpoise the Hall-signal output current at the input, and a voltage at the output is an amplified Hall output signal. A second amplifier generates a high-frequency portion output signal in response to a difference between the amplified Hall output signal and a Hall-signal output signal from a second Hall element. A filter reduces high-frequency content of the high-frequency portion output signal and generates an offset correction signal. A third amplifier generates a corrected Hall signal in response to a difference between the amplified Hall output signal and the offset correction signal.

Abstract: A first amplifier has an input to receive a Hall-signal output current from a first Hall element and has an output to output feedback current in response to the received Hall-signal output current. The Hall-signal output current is impeded by an impedance of the first Hall element. The feedback current is coupled to counterpoise the Hall-signal output current at the input, and a voltage at the output is an amplified Hall output signal. A second amplifier generates a high-frequency portion output signal in response to a difference between the amplified Hall output signal and a Hall-signal output signal from a second Hall element. A filter reduces high-frequency content of the high-frequency portion output signal and generates an offset correction signal. A third amplifier generates a corrected Hall signal in response to a difference between the amplified Hall output signal and the offset correction signal.

Abstract: In described examples, a Hall effect sensor includes a primary Hall effect sensor element and an auxiliary Hall effect sensor element. A known magnetic field is applied to the auxiliary Hall effect sensor to produce an auxiliary Hall voltage used in a feedback loop to control the bias current of the auxiliary Hall effect sensor to maintain the auxiliary Hall voltage approximately constant over a range of temperature and other factors. A bias current for the primary Hall effect sensor is controlled to track the bias current of the auxiliary Hall effect sensor to maintain the sensitivity of the primary Hall effect sensor approximately constant over the same range of temperature and other factors.

Abstract: An amplifier includes a graphene Hall sensor (GHS). The GHS includes a graphene layer formed above a substrate, a dielectric structure formed above a channel portion of the graphene layer, and a conductive gate structure formed above at least a portion of the dielectric structure above the channel portion of the graphene layer for applying a gate voltage. The GHS also includes first and second conductive excitation contact structures coupled with corresponding first and second excitation portions of the graphene layer for applying at least one of the following to the channel portion of the graphene layer: a bias voltage; and a bias current. The GHS further includes first and second conductive sense contact structures coupled with corresponding first and second sense portions of the graphene layer. The amplifier also includes a current sense amplifier (CSA) coupled to the GHS. The CSA senses current output from the GHS.

Abstract: One example includes a current measurement system. The system includes at least two magnetic field sensors positioned proximal to and in a predetermined arrangement with respect to a current conductor, each of the magnetic field sensors being configured to measure magnetic field associated with a current flowing in the current conductor and provide respective magnetic field measurements. The system also includes a current measurement processor configured to implement a mathematical algorithm based on a Taylor series expansion of the magnetic field measurements to calculate an amplitude of the current based on the mathematical algorithm.

Abstract: In described examples, a Hall effect sensor includes a primary Hall effect sensor element and an auxiliary Hall effect sensor element. A known magnetic field is applied to the auxiliary Hall effect sensor to produce an auxiliary Hall voltage used in a feedback loop to control the bias current of the auxiliary Hall effect sensor to maintain the auxiliary Hall voltage approximately constant over a range of temperature and other factors. A bias current for the primary Hall effect sensor is controlled to track the bias current of the auxiliary Hall effect sensor to maintain the sensitivity of the primary Hall effect sensor approximately constant over the same range of temperature and other factors.

Abstract: A microelectronic device includes a gated graphene component over a semiconductor material. The gated graphene component includes a graphitic layer having at least one layer of graphene. The graphitic layer has a channel region, a first connection and a second connection make electrical connections to the graphitic layer adjacent to the channel region. The graphitic layer is isolated from the semiconductor material. A backgate region having a first conductivity type is disposed in the semiconductor material under the channel region. A first contact field region and a second contact field region are disposed in the semiconductor material under the first connection and the second connection, respectively. At least one of the first contact field region and the second contact field region has a second, opposite, conductivity type. A method of forming the gated graphene component in the microelectronic device with a transistor is disclosed.

Abstract: A microelectronic device includes a gated graphene component over a semiconductor material. The gated graphene component includes a graphitic layer having at least one layer of graphene. The graphitic layer has a channel region, a first connection and a second connection make electrical connections to the graphitic layer adjacent to the channel region. The graphitic layer is isolated from the semiconductor material. A backgate region having a first conductivity type is disposed in the semiconductor material under the channel region. A first contact field region and a second contact field region are disposed in the semiconductor material under the first connection and the second connection, respectively. At least one of the first contact field region and the second contact field region has a second, opposite, conductivity type. A method of forming the gated graphene component in the microelectronic device with a transistor is disclosed.

Abstract: A high bandwidth Hall sensor includes a high bandwidth path and a low bandwidth path. The relatively high offset (from sensor offset) of the high bandwidth path is estimated using a relatively low offset generated by the low bandwidth path. The relatively high offset of the high bandwidth path is substantially reduced by combining the output of the high bandwidth path with the output of the low bandwidth path to generate a high bandwidth, low offset output. The offset can be further reduced by including transimpedance amplifiers in the high bandwidth sensors to optimize the frequency response of high bandwidth Hall sensor.

Abstract: An LED (light-emitting diode) driver for a photoplethysmography system, including a switched-mode operational amplifier for driving a driver transistor with a source-drain path in series with the LED. In a first clock phase in which the LED is disconnected from the driver transistor, the amplifier is coupled in unity gain mode, and a sampling capacitor stores a voltage corresponding to the offset and flicker noise of the amplifier; the gate of the driver transistor is precharged to a reference voltage in this first clock phase. In a second clock phase, the sampled voltage at the capacitor is subtracted from the reference voltage applied to the amplifier input, so that the LED drive is adjusted according to the sampled noise. A signal from the transmitter channel is forwarded to a noise/ripple remover in the receiving channel, to remove transmitter noise from the received signal.

Abstract: A first amplifier has an input to receive a Hall-signal output current from a first Hall element and has an output to output feedback current in response to the received Hall-signal output current. The Hall-signal output current is impeded by an impedance of the first Hall element. The feedback current is coupled to counterpoise the Hall-signal output current at the input, and a voltage at the output is an amplified Hall output signal. A second amplifier generates a high-frequency portion output signal in response to a difference between the amplified Hall output signal and a Hall-signal output signal from a second Hall element. A filter reduces high-frequency content of the high-frequency portion output signal and generates an offset correction signal. A third amplifier generates a corrected Hall signal in response to a difference between the amplified Hall output signal and the offset correction signal.

Abstract: A system for measuring current includes a conductive trace comprising N substantially parallel straight sections having a substantially constant cross-section, N?4. Adjacent substantially straight sections are spaced apart by a given distance and each pair of adjacent straight sections is connected by a respective loop of the current trace such that current in odd-numbered straight sections flows in a first direction and current in even-numbered straight sections flows in an opposite direction. The N magnetic field based current sensors are each positioned on a respective straight section of the conductive trace.

Abstract: Graphene Hall sensors, magnetic sensor systems and methods for sensing a magnetic field using an adjustable gate voltage to adapt the Hall sensor magnetic field sensitivity according to a control input for environmental or process compensation and/or real-time adaptation for balancing power consumption and minimum detectable field performance. The graphene Hall sensor gate voltage can be modulated and the sensor output signal can be demodulated to combat flicker or other low frequency noise. Also, graphene Hall sensors can be provided with capacitive coupled contacts for reliable low impedance AC coupling to instrumentation amplifiers or other circuits using integral capacitance.