Closed-loop magnetoresistive current sensor system having active offset nulling
US6445171B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 29, 1999 |
| Grant date | Sep 3, 2002 |
| Priority date | — |
| Expiry date | Oct 29, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R15/205
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A magnetoresistive sensor system having resistive elements changing in ohmic value in the presence of a magnetic field of a current being measured. The variant values of the elements are amplified by some electronics that inherently add offset to the resultant values. The elements themselves also add an offset. The output of the electronics is modulated and then buffered as an output.This output is demodulated integrated. The resultant signal is fed back to the input of the electronics to null out the offsets. The output of the buffer also goes to an inductive coil that is magnetically coupled to the resistive elements to null out the magnetic field from the current being measured. The buffer output indicates the magnitude of the current being measured. An oscillator outputs a signal to actuate the modulator and the demodulator. The oscillator signal also goes to a set/reset circuit for setting and resetting the resistive elements of the magnetoresistive sensor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.