Abstract: A logarithmic converter circuit includes a converter input and a converter output. The circuit includes a first transistor which includes a control terminal, a first terminal coupled to the converter input, and a second terminal coupled to the converter output. The circuit includes a first operational amplifier which includes a first input coupled to the converter input, a second input coupled to a common potential, and an output coupled to the second terminal. The circuit includes a first capacitor coupled between the first terminal and the control terminal and includes a first resistor coupled between the control terminal and the common potential.

Abstract: A system includes an instrumentation amplifier (INA) including a first transistor coupled to a first input node, and a second transistor coupled to a second input node. The INA also includes a resistor coupled between the first transistor and the second transistor. The INA includes a gain resistor network coupled to the resistor and to the first and second transistors, where the gain resistor network includes two or more gain resistors. The system also includes a voltage to current converter, where the voltage to current converter is coupled to the resistor and the gain resistor network.

Abstract: A system includes an instrumentation amplifier (INA) including a first transistor coupled to a first input node, and a second transistor coupled to a second input node. The INA also includes a resistor coupled between the first transistor and the second transistor. The INA includes a gain resistor network coupled to the resistor and to the first and second transistors, where the gain resistor network includes two or more gain resistors. The system also includes a voltage to current converter, where the voltage to current converter is coupled to the resistor and the gain resistor network.

Abstract: Improved magnetic component models, circuit simulation systems and methods are presented for simulating operation of a modeled magnetic circuit component in which user input defines magnetically susceptible core geometry of the modeled magnetic circuit component, a core model simulates operation of the magnetically susceptible core at least partially according to the geometry of the magnetically susceptible core, and one or more coil models simulate operation of coils wound around the magnetically susceptible core to provide a scalable model with geometry adjustable permeability for fluxgate magnetic sensors, transformers, inductors or other modeled components.

Abstract: Disclosed embodiments include a method for reducing amplifier offset drift comprised of receiving a first differential input signal at a first transistor base terminal and a second differential input signal at a second transistor base terminal, coupling the collector of the first transistor to the emitter of a third transistor and the emitter of the second transistor to the emitter of a fourth transistor, then coupling the base of the third transistor to the base of the fourth transistor. The method is also comprised of coupling the collector of the fourth transistor to an output terminal, generating a temperature dependent error correction current to minimize the difference in the amount of current flowing through the third transistor and the amount of current flowing through the fourth transistor, then injecting the error correction current into the emitter terminal of at least one of either the third transistor or the fourth transistor.

Abstract: An overvoltage protection circuit includes an input terminal, an output terminal, a clamp transistor, and a selector circuit. The clamp transistor is configured to control current flow between the input terminal and the output terminal. The clamp transistor includes a first terminal coupled to the input terminal, a second terminal coupled to the output terminal. The selector circuit is configured to control a resistance of the clamp transistor based on a voltage at the input terminal. The selector circuit includes a first terminal coupled to the first terminal of the clamp transistor, a second terminal coupled to the second terminal of the clamp transistor, and a third terminal coupled to a third terminal of the clamp transistor.

Abstract: Disclosed embodiments include a method for reducing amplifier offset drift comprised of receiving a first differential input signal at a first transistor base terminal and a second differential input signal at a second transistor base terminal, coupling the collector of the first transistor to the emitter of a third transistor and the emitter of the second transistor to the emitter of a fourth transistor, then coupling the base of the third transistor to the base of the fourth transistor. The method is also comprised of coupling the collector of the fourth transistor to an output terminal, generating a temperature dependent error correction current to minimize the difference in the amount of current flowing through the third transistor and the amount of current flowing through the fourth transistor, then injecting the error correction current into the emitter terminal of at least one of either the third transistor or the fourth transistor.

Abstract: A circuit and method for magnetic field detection is disclosed. A fluxgate sensor comprises a fluxgate having a first core and a second core. A sense coil has a first winding around the first fluxgate core and a second winding around the second fluxgate core. A fluxgate detection circuit is coupled to the sense coil and outputs a signal proportional to an external magnetic field applied to the fluxgate. A detection circuit is coupled to the first winding and outputs a signal that indicates whether voltage pulses have been detected on the first winding.

Abstract: An integrated fluxgate magnetic gradient sensor includes a common mode sensitive fluxgate magnetometer and a differential mode sensitive fluxgate magnetometer. The common mode sensitive fluxgate magnetometer includes a first core adjacent to a second core. The first and second cores are wrapped by a first excitation wire coil configured to receive an excitation current that affects a differential mode magnetic field. The differential mode sensitive fluxgate magnetometer includes a third core adjacent to the first core and a fourth core adjacent to the second core. The third and fourth cores are wrapped by a second excitation wire coil configured to receive an excitation current that affects a common mode magnetic field.

Abstract: An overvoltage protection circuit includes an input terminal, an output terminal, a clamp transistor, and a selector circuit. The clamp transistor is configured to control current flow between the input terminal and the output terminal. The clamp transistor includes a first terminal coupled to the input terminal, a second terminal coupled to the output terminal. The selector circuit is configured to control a resistance of the clamp transistor based on a voltage at the input terminal. The selector circuit includes a first terminal coupled to the first terminal of the clamp transistor, a second terminal coupled to the second terminal of the clamp transistor, and a third terminal coupled to a third terminal of the clamp transistor.

Abstract: An integrated fluxgate magnetic gradient sensor includes a common mode sensitive fluxgate magnetometer and a differential mode sensitive fluxgate magnetometer. The common mode sensitive fluxgate magnetometer includes a first core adjacent to a second core. The first and second cores are wrapped by a first excitation wire coil configured to receive an excitation current that affects a differential mode magnetic field. The differential mode sensitive fluxgate magnetometer includes a third core adjacent to the first core and a fourth core adjacent to the second core. The third and fourth cores are wrapped by a second excitation wire coil configured to receive an excitation current that affects a common mode magnetic field.

Abstract: An integrated fluxgate magnetic gradient sensor includes a common mode sensitive fluxgate magnetometer and a differential mode sensitive fluxgate magnetometer. The common mode sensitive fluxgate magnetometer includes a first core adjacent to a second core. The first and second cores are wrapped by a first excitation wire coil configured to receive an excitation current that affects a differential mode magnetic field. The differential mode sensitive fluxgate magnetometer includes a third core adjacent to the first core and a fourth core adjacent to the second core. The third and fourth cores are wrapped by a second excitation wire coil configured to receive an excitation current that affects a common mode magnetic field.

Abstract: Improved magnetic sensor excitation circuitry is presented for providing a periodic bidirectional excitation waveform to a fluxgate magnetic sensor excitation coil using a bridge circuit connected to the excitation coil and having lower transistors for switched selective connection to a current mirror input transistor to mirror a current provided by pulsed current source, and with integrated filtering to control pulse rise times and slew rate.

Abstract: Compact, low power fluxgate magnetic sensor readout circuits and apparatus are presented in which demodulator or rectifier circuit to modulates a sense signal from the fluxgate sense coil, and the demodulated signal is provided to an amplifier circuit with a transconductance or other amplifier and one or more feedback capacitors connected between the amplifier input and amplifier output to integrate the amplifier output current and provide a voltage output signal indicating the magnetic field sensed by the fluxgate sensor.

Abstract: An integrated fluxgate magnetic gradient sensor includes a common mode sensitive fluxgate magnetometer and a differential mode sensitive fluxgate magnetometer. The common mode sensitive fluxgate magnetometer includes a first core adjacent to a second core. The first and second cores are wrapped by a first excitation wire coil configured to receive an excitation current that affects a differential mode magnetic field. The differential mode sensitive fluxgate magnetometer includes a third core adjacent to the first core and a fourth core adjacent to the second core. The third and fourth cores are wrapped by a second excitation wire coil configured to receive an excitation current that affects a common mode magnetic field.

Abstract: A circuit and method for magnetic field detection is disclosed. A fluxgate sensor comprises a fluxgate having a first core and a second core. A sense coil has a first winding around the first fluxgate core and a second winding around the second fluxgate core. A fluxgate detection circuit is coupled to the sense coil and outputs a signal proportional to an external magnetic field applied to the fluxgate. A detection circuit is coupled to the first winding and outputs a signal that indicates whether voltage pulses have been detected on the first winding.

Abstract: Improved magnetic component models, circuit simulation systems and methods are presented for simulating operation of a modeled magnetic circuit component in which user input defines magnetically susceptible core geometry of the modeled magnetic circuit component, a core model simulates operation of the magnetically susceptible core at least partially according to the geometry of the magnetically susceptible core, and one or more coil models simulate operation of coils wound around the magnetically susceptible core to provide a scalable model with geometry adjustable permeability for fluxgate magnetic sensors, transformers, inductors or other modeled components.

Abstract: A method of processing an output signal and a readout circuit for a magnetic field sensor are disclosed. The purpose of the readout circuit is to generate a digital representation of the magnetic field vector strength. It comprises an input stage for receiving an output signal of the magnetic field sensor; an output stage for outputting a digital output signal corresponding to the sensor output signal; and an analog to digital conversion circuit. The analog to digital conversion circuit receives the sensor output signal and performs, in sequence, a fast conversion process for calculating a number of most significant bits of the digital output signal corresponding to the sensor output signal and for generating a compensation signal, and a delta sigma based conversion process for calculating at least one least significant bit of the digital output signal. The compensation signal is fed back to the sensor input for linearization.

Abstract: Hybrid magnetic current sensors and sensing apparatus are presented with closed-loop and open-loop circuitry employs first and second integrated magnetic sensors to sense a magnetic field in a magnetic core structure gap to provide high accuracy current measurement via a closed-loop magnetic circuit with the first sensor in a nominal current range as well as open-loop current measurement using the second sensor in an extended second range to accommodate over-current conditions in a host system as well as to provide redundant current sensing functionality.

Abstract: Compact, low power fluxgate magnetic sensor readout circuits and apparatus are presented in which demodulator or rectifier circuit to modulates a sense signal from the fluxgate sense coil, and the demodulated signal is provided to an amplifier circuit with a transconductance or other amplifier and one or more feedback capacitors connected between the amplifier input and amplifier output to integrate the amplifier output current and provide a voltage output signal indicating the magnetic field sensed by the fluxgate sensor.