Method and apparatus for calculating offset of wheatstone bridge type sensor

An apparatus for a planar hall resistance (PHR) sensor comprising a first node, a second node, a third node and a fourth node arranged in order, the apparatus comprising:

• a first measurement unit configured to measure a first resistance between the first node and the second node when the PHR sensor is mounted in the apparatus;
• a second measurement unit configured to measure a second resistance between the second node and the third node when the PHR sensor is mounted in the apparatus;
• a third measurement unit configured to measure a third resistance between the third node and the fourth node when the PHR sensor is mounted in the apparatus;
• a fourth measurement unit configured to measure a fourth resistance between the fourth node and the first node when the PHR sensor is mounted in the apparatus;
• a reference offset calculator connected to the first, second, third and fourth measurement units and configured to apply the first, second, third and fourth resistances to a predetermined formula to calculate a reference offset of the PHR sensor, the reference offset being a value independent from a bias current of the PHP sensor;
• a display connected to the reference offset calculator and configured to display the reference offset;
• and
• an input device connected to the reference offset calculator configured to receive a user input of a first bias current,
• wherein, in response to the user input, the reference offset calculator is further configured to compute a first offset for the PHR sensor based on the reference offset and the first bias current and wherein the display is further configured to display the first offset.