Abstract: In a position detector for converting, into position information, two signals shifted in phase by 90 degrees from each other, a phase correction value calculator for calculating a phase correction value for correcting a phase difference between the two signals calculates a phase change value representing a change in the phase correction value, to find a next phase correction value based on the phase change value and a present phase correction value. A virtual change value calculator calculates, based on second-order components obtained by Fourier analysis of a radius value, a virtual phase change value representing another change in the phase correction value obtained when changes in offset and amplitude ratio are ignored, and a virtual amplitude change value representing a change rate in an amplitude ratio correction value obtained when a change in the phase difference is ignored.

Abstract: In a position detector for converting, into position information, two signals shifted in phase by 90 degrees from each other, a phase correction value calculator for calculating a phase correction value for correcting a phase difference between the two signals calculates a phase change value representing a change in the phase correction value, to find a next phase correction value based on the phase change value and a present phase correction value. A virtual change value calculator calculates, based on second-order components obtained by Fourier analysis of a radius value, a virtual phase change value representing another change in the phase correction value obtained when changes in offset and amplitude ratio are ignored, and a virtual amplitude change value representing a change rate in an amplitude ratio correction value obtained when a change in the phase difference is ignored.