Patent ID: 8004276

Claim:
A reference signal generation circuit for generating a reference signal used in synchronous detection for removing an excitation signal component in an angle calculation section that converts a detection angle θ obtained from two-phase resolver detection signals output from a resolver excited by an excitation signal sin ωt, to a digital output angle φ, the reference signal generation circuit comprising: a first multiplier for multiplying a first resolver detection signal sin θ sin(ωt+Δω), where Δω indicates a phase difference between the excitation signal and the excitation signal component, by the sine value sin φ of the digital output angle φ obtained from the angle calculation section; a second multiplier for multiplying a second resolver detection signal cos θ sin(ωt+Δω) by the cosine value cos φ of the digital output angle φ obtained from the angle calculation section; and an adder for adding the output of the first multiplier and the output of the second multiplier to output the sum signal sin(ωt+Δω) as the reference signal.