Absolute position sensor

A target structure for use in a magnetic field sensing system, the target structure comprising:

• a plurality of n+1 coil elements each having a receiver coil, a first transmitter coil connected to the receiver coil, and a second transmitter coil connected to the receiver coil,
• wherein the first transmitter coils are spaced apart by a first pitch
• n
• +
• 1
• n
• ⁢
• P
• and the second transmitter coils are spaced apart by a second pitch P different from the first pitch, wherein n is an integer greater than 0.

A system comprising:

• a magnetic field sensor comprising:
• an emitting coil configured to generate a magnetic field in response to a current through the emitting coil,
• a first arrangement of magnetic field sensing elements comprising a first group of four sensing elements, and
• a second arrangement of magnetic field sensing elements comprising a second group of four sensing elements;
• and
• a target configured to move relative to the magnetic field sensor and comprising:
• a plurality of n+1 target coil elements each having a receiver coil, a first transmitter coil connected to the receiver coil, and a second transmitter coil connected to the receiver coil, wherein adjacent pairs of the first transmitter coils are spaced apart by a first pitch n+1/n Pand adjacent pairs of the second transmitter coils are spaced apart by a second pitch P, wherein n is an integer greater than 0,
• wherein the magnetic field sensor is configured to:
• calculate a first phase angle from one or more signals generated by the first arrangement of magnetic field sensing elements,
• calculate a second phase angle from one or more signals generated by the second arrangement of magnetic field sensing elements, and
• determine an absolute position of the target using the first phase angle and the second phase angle.