Temperature and drift compensation in magnetoresistive sensors

US8405385B2 · kind B2 · utility

Assignee

• The Board of Trustees of the Leland Stanford Junior University · US

Inventors

• Drew Hall · Village of La Jolla, US
• Richard S. Gaster · Los Altos, US
• Sebastian J. Osterfeld · Mountain View, US
• Shan X. Wang · Portola Valley, US

Key dates

• Filing date: Mar 10, 2010
• Grant date: Mar 26, 2013
• Expiry date: Aug 20, 2031

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R33/093
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Double modulation of a magnetoresistive sensor entails modulating both an excitation (e.g., voltage or current) applied to the sensor and a tickling magnetic field applied to the sensor. The excitation and magnetic field are modulated at different frequencies fc and ff, respectively. As a result of the double modulation, the sensor output spectrum includes a carrier tone (CT) at frequency fc and side tones (STs) at frequencies fc±ff. A baseline relation between CT amplitude and ST amplitude is determined (e.g., by measuring CT and ST amplitude while drift occurs in the absence of a sample). During sensor operation, raw ST measurements are corrected using corresponding raw CT measurements to provide corrected ST measurements as the sensor output.