Abstract: A high bandwidth Hall sensor includes, for example, a Hall element for generating a first polarity Hall-signal output current. An amplifier receives, at a first input, the first polarity Hall-signal output current and outputs a feedback current of a second polarity opposite the first polarity in response. The feedback current is coupled to the first input, and the feedback current suppresses an instantaneous voltage generated by the first polarity first Hall element output current at the first input. In an embodiment, the feedback current suppresses the instantaneous voltage generated by first polarity Hall element output current such that the effects of the Hall element source impedance are reduced.

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: A Graphene Hall sensor (GHS) is provided with a modulated gate bias signal in which the modulated gate bias signal alternates at a modulation frequency between a first voltage that produces a first conductivity state in the GHS and a second voltage that produces approximately a same second conductivity state in the GHS. A bias current is provided through a first axis of the GHS. A resultant output voltage signal is provided across a second axis of the Hall sensor that includes a modulated Hall voltage and an offset voltage, in which the Hall voltage is modulated at the modulation frequency. An amplitude of the Hall voltage that does not include the offset voltage is extracted from the resultant output voltage signal.

Abstract: A high bandwidth Hall sensor includes, for example, a Hall element for generating a first polarity Hall-signal output current. An amplifier receives, at a first input, the first polarity Hall-signal output current and outputs a feedback current of a second polarity opposite the first polarity in response. The feedback current is coupled to the first input, and the feedback current suppresses an instantaneous voltage generated by the first polarity first Hall element output current at the first input. In an embodiment, the feedback current suppresses the instantaneous voltage generated by first polarity Hall element output current such that the effects of the Hall element source impedance are reduced.

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: A closed-loop calibration scheme is configured to allow a device to remain in continuous operation. A signal generator device provides a pseudorandom sequence for a signal received by a magnetic field magnetic field sensor, such as a Hall-effect sensor. A signal decoder circuit receives the output signal and decouples the generated spread spectrum signal from the interference by measuring the gain in the overall signal. The decoder device distinguishes the known spread spectrum signal from any perturbation effects of particular bandwidths. A processing circuit then outputs a signal that has an operation parameter that has been adjusted to compensate for the perturbation effects. The processing circuit provides the receiver circuit with the compensation signal, hence forming a closed-loop calibration configuration.

Abstract: Operating a current sensor by conducting a current serially through a first region and a second region of an electrically conductive member. A first magnetic field produced by the current in the first region is sensed using a first magnetic field based current (MFBC) sensor having a first sensitivity. The sensitivity of a second MFBC is reduced. A second magnetic field produced by the current in the second region is sensed using the second MFBC sensor having a reduced sensitivity, in which the reduced sensitivity is lower than the first sensitivity. A magnitude of the current is calculated based on the first magnetic field and the second magnetic field. A dynamic range of the current sensor is extended by calculating a magnitude of the current using the second magnetic field after the first MFBC is saturated.

Abstract: Methods and apparatus for magnetic sensors and integrated calibration. In an example arrangement, a system includes a magnetic sensor configured to output a signal corresponding to magnetic fields; a calibration trace disposed proximal to the magnetic sensor; a controlled current source coupled to the calibration trace and configured to output a current resulting in a magnetic field output from the calibration trace; and a comparator coupled to the output signal from the magnetic sensor and to an expected signal. In the example arrangement, the comparator outputs a signal indicating whether the output signal from the magnetic sensor corresponds to the expected signal. Methods are also disclosed.

Abstract: An analog to digital converter (ADC) system that includes a first amplifier configured to amplify an analog input signal to produce an amplified direct current (DC) signal, an ADC configured to receive the amplified DC signal and convert the amplified DC signal into a digital DC signal, a digital to analog converter configured to receive the digital DC signal and convert the digital DC signal into an analog DC signal, and a second amplifier configured to receive an analog alternating current (AC) signal comprising the analog DC signal subtracted from the analog input signal and amplify the analog AC signal to produce an amplified AC signal. The ADC is further configured to receive the amplified AC signal and produce a digital AC signal. The second amplifier has a gain greater than a gain of the first amplifier.

Abstract: The circuitry of an optical receiver reduces the ambient DC component and the pleth DC component to leave a pleth signal with substantially only a pleth AC component. The circuitry also provides gain control and can provide transmit power control to change the range of the pleth AC component to occupy a desired input range of an analog-to-digital converter.

Abstract: A closed-loop calibration scheme is configured to allow a device to remain in continuous operation. A signal generator device provides a pseudorandom sequence for a signal received by a magnetic field magnetic field sensor, such as a Hall-effect sensor. A signal decoder circuit receives the output signal and decouples the generated spread spectrum signal from the interference by measuring the gain in the overall signal. The decoder device distinguishes the known spread spectrum signal from any perturbation effects of particular bandwidths. A processing circuit then outputs a signal that has an operation parameter that has been adjusted to compensate for the perturbation effects. The processing circuit provides the receiver circuit with the compensation signal, hence forming a closed-loop calibration configuration.

Abstract: An analog to digital converter (ADC) system that includes a first amplifier configured to amplify an analog input signal to produce an amplified direct current (DC) signal, an ADC configured to receive the amplified DC signal and convert the amplified DC signal into a digital DC signal, a digital to analog converter configured to receive the digital DC signal and convert the digital DC signal into an analog DC signal, and a second amplifier configured to receive an analog alternating current (AC) signal comprising the analog DC signal subtracted from the analog input signal and amplify the analog AC signal to produce an amplified AC signal. The ADC is further configured to receive the amplified AC signal and produce a digital AC signal. The second amplifier has a gain greater than a gain of the first amplifier.

Abstract: Reduced noise and power with rapid settling time and increased performance in multi-modal analog multiplexed data acquisition systems. An example apparatus arrangement includes a circuit input configured to receive a plurality of analog input signals; an analog to digital converter circuit configured to output a digital representation of an analog voltage; a selection circuit configured to select one of the analog input signals received at the circuit input; a buffer coupled to receive the selected one of the analog input signals; a filter coupled to the buffer and configured to perform a high bandwidth sample operation and a low bandwidth sample operation and having a filter output, responsive to a control signal; and a sampling capacitor coupled to the filter to sample the filter output, and having an output coupled to the analog to digital converter. Methods and additional apparatus arrangements are disclosed.

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: An optical system includes an optical illumination source, an optical receiver, a correlation determination circuit, and an ambient condition control circuit. The optical illumination source is configured to emit a light in the direction of a target object. The optical receiver is configured to receive a combined optical signal that includes an ambient light component combined with an interrogation component. The correlation determination circuit is configured to compare the combined optical signal with an ambient light signal to identify a correlation factor. The ambient condition control circuit is configured to compare the correlation factor to a low correlation threshold value and a high correlation threshold value, and, based on the correlation factor exceeding the low threshold value and being less than the high correlation threshold value, cancel the ambient light component from the combined optical signal to produce an interrogation signal including the interrogation component.

Abstract: Methods and apparatus for magnetic sensors and integrated calibration. In an example arrangement, a system includes a magnetic sensor configured to output a signal corresponding to magnetic fields; a calibration trace disposed proximal to the magnetic sensor; a controlled current source coupled to the calibration trace and configured to output a current resulting in a magnetic field output from the calibration trace; and a comparator coupled to the output signal from the magnetic sensor and to an expected signal. In the example arrangement, the comparator outputs a signal indicating whether the output signal from the magnetic sensor corresponds to the expected signal. Methods are also disclosed.

Abstract: A Graphene Hall sensor (GHS) may be provided with a modulated gate bias signal in which the modulated gate bias signal alternates at a modulation frequency between a first voltage that produces a first conductivity state in the GHS and a second voltage that produces approximately a same second conductivity state in the GHS. A bias current may be provided through a first axis of the GHS. A resultant output voltage signal may be provided across a second axis of the Hall sensor that includes a modulated Hall voltage and an offset voltage, in which the Hall voltage is modulated at the modulation frequency. An amplitude of the Hall voltage that does not include the offset voltage may be extracted from the resultant output voltage signal.

Abstract: Operating a current sensor by conducting a current serially through a first region and a second region of an electrically conductive member. A first magnetic field produced by the current in the first region is sensed using a first magnetic field based current (MFBC) sensor having a first sensitivity. The sensitivity of a second MFBC is reduced. A second magnetic field produced by the current in the second region is sensed using the second MFBC sensor having a reduced sensitivity, in which the reduced sensitivity is lower than the first sensitivity. A magnitude of the current is calculated based on the first magnetic field and the second magnetic field. A dynamic range of the current sensor is extended by calculating a magnitude of the current using the second magnetic field after the first MFBC is saturated.

Abstract: Reduced noise and power with rapid settling time and increased performance in multi-modal analog multiplexed data acquisition systems. An example apparatus arrangement includes a circuit input configured to receive a plurality of analog input signals; an analog to digital converter circuit configured to output a digital representation of an analog voltage; a selection circuit configured to select one of the analog input signals received at the circuit input; a buffer coupled to receive the selected one of the analog input signals; a filter coupled to the buffer and configured to perform a high bandwidth sample operation and a low bandwidth sample operation and having a filter output, responsive to a control signal; and a sampling capacitor coupled to the filter to sample the filter output, and having an output coupled to the analog to digital converter. Methods and additional apparatus arrangements are disclosed.

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.