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Ultra-low noise sensor for magnetic fields

  • US 10,018,686 B1
  • Filed: 10/21/2015
  • Issued: 07/10/2018
  • Est. Priority Date: 10/21/2015
  • Status: Active Grant
First Claim
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1. A sensor for magnetic fields comprising:

  • a micromachined body;

    at least one magnet attached to the body and, together with the body, forming a proof mass;

    one or more micromachined flexures mechanically connected between the body and a substrate, wherein the proof mass and the flexures form a resonant structure having a high quality factor and a resonance frequency;

    two pieces of magnetically permeable material, located on opposite sides of the proof mass, each at a separation distance from the proof mass, and configured to concentrate magnetic flux at a location of the proof mass;

    a high resolution readout system having a level of input-referred readout noise, configured to provide an electrical output as a function of displacement of the proof mass;

    a processor operatively connected to the readout system and having a frequency compensating transfer function; and

    a solenoid coil surrounding the proof mass and configured as part of a feedback loop to null a magnetic field at the location of the proof mass and at frequencies below a threshold frequency.

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