SLYA085 December   2023 TMAG6180-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2AMR Angle Sensing
  6. 3Calibrating AMR
    1. 3.1 Input Related Errors
    2. 3.2 Sensor Related Errors
    3. 3.3 Offset
    4. 3.4 Amplitude Mismatch
    5. 3.5 Orthogonality Error
    6. 3.6 Noise
  7. 4Summary
  8. 5References

3.2 Sensor Related Errors

There are four main device-level sources of error to consider with any AMR angle sensor:

  • Offset
  • Amplitude Mismatch
  • Orthogonality Error
  • Noise

These errors are better understood by comparing multiple Lissajous curves against an error-free unit circle.

GUID-20220627-SS0I-BQMH-R9X6-KDTPSJ1RN9SP-low.svg Figure 3-8 Angle Accuracy Impact Owing to Sensor Electrical Errors, Offset Error (a), Amplitude Mismatch Error (b), and Orthogonality Error (c)

Sections Offset, Amplitude Mismatch, and Orthogonality Error define the plot relationships of Figure 3-8. When differential outputs are available, the effective output mode can be described by Equation 3 and Equation 4. These relationships are used in subsequent calculations, but can be replaced with a single output if calculations are made with a single-ended value.

Equation 3. sin d i f f = sin P   -     sin N
Equation 4. cos d i f f = cos P   -     cos N