A system for determining a stuck point of a pipe positioned within a wellbore includes a tubular housing and a sensor array positioned within the tubular housing. The system also includes ferromagnetic flux collectors and flux concentrators on either side of the sensor array. The flux collectors collect a magnetic flux that has been written to a portion of pipe. The flux concentrators intensify the flux to improve measurements of the flux that are acquired by the sensor array.

A system for determining a stuck point of a pipe positioned within a wellbore includes a tubular housing and a sensor array positioned within the tubular housing. The system also includes ferromagnetic flux collectors and flux concentrators on either side of the sensor array. The flux collectors collect a magnetic flux that has been written to a portion of pipe. The flux concentrators intensify the flux to improve measurements of the flux that are acquired by the sensor array.

An integrated circuit has a substrate, a circuit, a core structure, a first encapsulation layer, a second encapsulation layer, and an oxide layer. The circuit includes transistors with active regions developed on the substrate and a metal layer formed above the active regions to provide interconnections for the transistors. The core structure is formed above the metal layer. The first encapsulation layer covers the core structure, and it has a first thermal expansion coefficient. The second encapsulation layer covers the first encapsulation layer over the core structure, and it has a second thermal expansion coefficient that is different from the first thermal expansion coefficient. As a part of the stress relief structure, the oxide layer is formed above the second encapsulation layer. The oxide layer includes an oxide thickness sufficient to mitigate a thermal stress between the first and second encapsulation layers.

An integrated circuit has a substrate, a circuit, a core structure, a first encapsulation layer, a second encapsulation layer, and an oxide layer. The circuit includes transistors with active regions developed on the substrate and a metal layer formed above the active regions to provide interconnections for the transistors. The core structure is formed above the metal layer. The first encapsulation layer covers the core structure, and it has a first thermal expansion coefficient. The second encapsulation layer covers the first encapsulation layer over the core structure, and it has a second thermal expansion coefficient that is different from the first thermal expansion coefficient. As a part of the stress relief structure, the oxide layer is formed above the second encapsulation layer. The oxide layer includes an oxide thickness sufficient to mitigate a thermal stress between the first and second encapsulation layers.

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.

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.

A flux gate current sensor includes a magnetic core, a measurement winding, an excitation circuit arranged to generate a digital excitation signal, an acquisition circuit arranged to acquire an analog measurement voltage from the terminals of the measurement winding and to produce a digital measurement signal, a demagnetization servocontrol circuit arranged to use the digital measurement signal to produce a digital demagnetization signal for compensating magnetic flux produced by the current that is to be measured, a summing circuit arranged to sum the digital excitation signal and the digital demagnetization signal so as to obtain a digital injection signal, and an injection circuit arranged to produce an analog excitation current from the digital injection signal and to inject the analog excitation current into the measurement winding.

A flux gate current sensor includes a magnetic core, a measurement winding, an excitation circuit arranged to generate a digital excitation signal, an acquisition circuit arranged to acquire an analog measurement voltage from the terminals of the measurement winding and to produce a digital measurement signal, a demagnetization servocontrol circuit arranged to use the digital measurement signal to produce a digital demagnetization signal for compensating magnetic flux produced by the current that is to be measured, a summing circuit arranged to sum the digital excitation signal and the digital demagnetization signal so as to obtain a digital injection signal, and an injection circuit arranged to produce an analog excitation current from the digital injection signal and to inject the analog excitation current into the measurement winding.

A low-noise magnetoresistive sensor includes a substrate and an array of magnetic modulation structures on the substrate. The structure includes upper and lower soft ferromagnetic layers and a conductive metal layer in the middle. The two ends of the structure are connected to form a two-port excitation coil. Adjacent structures have opposite current directions. A magnetoresistive sensing unit is located above or below and is centered in the gap between the structures. The sensitive direction of the sensing units is perpendicular to a long direction of the structures. An array of sensing units is electrically connected to form a magnetoresistive sensor, and the sensor is connected to the sensor bond pads. When measuring an external magnetic field, an excitation current is applied to the excitation coil, and the output of the voltage or current signal of the magnetoresistive sensor is demodulated to produce a low-noise voltage signal.

The present disclosure relates to a magnetic sensor that comprises a magnetic-sensing element and a magnetic-affecting element. The magnetic sensor is configured for detecting one or more properties, and/or changes therein, of a target magnetic-field. Further embodiments of the present disclosure relate to a sensor unit that houses and protects the magnetic sensor described herein. Further embodiments of the present disclosure relate to a system that comprises the magnetic sensor alone or the sensor unit described herein. Further embodiments of the present disclosure relate to a method for detecting changes in a target magnetic-field. The magnetic sensor described herein comprises a magnetic-sensing element and a magnetic-affecting element. The magnetic-affecting element attracts or attracts and focuses the target magnetic-field through the magnetic-sensing element.