Magnetic Sensor

A magnetic sensor for detecting an angle that a direction of an external magnetic field in a reference position forms with respect to a reference direction, the external magnetic field rotating in direction, the magnetic sensor comprising:

• a first detection unit for detecting a first angle that the direction of the external magnetic field in a first position forms with respect to a first direction;
• and
• a second detection unit for detecting a second angle that the direction of the external magnetic field in a second position forms with respect to a second direction, wherein:
• the first detection unit includes first and second detection circuits each of which detects an intensity of a component of the external magnetic field in one direction and outputs a signal indicating the intensity, and a first arithmetic circuit that calculates a first detection angle based on the output signals of the first and second detection circuits, the first detection angle being a detected value of the first angle, the output signal of the first detection circuit and the output signal of the second detection circuit differing in phase by an odd number of times ¼ of a period of the output signals of the first and second detection circuits;
• the second detection unit includes third and fourth detection circuits each of which detects an intensity of a component of the external magnetic field in one direction and outputs a signal indicating the intensity, and a second arithmetic circuit that calculates a second detection angle based on the output signals of the third and fourth detection circuits, the second detection angle being a detected value of the second angle, the output signal of the third detection circuit and the output signal of the fourth detection circuit differing in phase by an odd number of times ¼ of a period of the output signals of the third and fourth detection circuits;
• the first detection angle includes a first angular error with respect to a theoretical value of the first angle that is assumed when the direction of the external magnetic field rotates in an ideal way;
• the second detection angle includes a second angular error with respect to a theoretical value of the second angle that is assumed when the direction of the external magnetic field rotates in an ideal way;
• the first angular error and the second angular error make periodical changes at an equal error period in response to a change of the direction of the external magnetic field, the change of the first angular error and the change of the second angular error depending on the change of the direction of the external magnetic field;
• and
• the first position and the second position are different from each other, and an interval between the first position and the second position is equivalent to an odd number of times ½ of the error period,
• the magnetic sensor further comprising a third arithmetic circuit that calculates a detected value of the angle that the direction of the external magnetic field in the reference position forms with respect to the reference direction, based on the first detection angle and the second detection angle.