| 摘要 |
PURPOSE: To compensate an angle error due to offset by providing an operation means for obtaining the difference of A/D converter output for an input signal and a signal for compensating offset. CONSTITUTION: When SW2 of a signal switching means 2 is off and SW1 is on, a sinusoidal wave (s+h) is inputted to an A/D converter 4 and is converted into a digital signal (S+H+A) to be outputted. On the other hand, when the SW1 is off and SW2 is on, a reference voltage (h) is converted into a digital signal (H+A) by the A/D converter 4. Then, a difference signal S between both output signals is obtained by the operation of an operation means 3. A signal C is obtained as in a sinusoidal wave (s) also for a cosine signal (c). An X, Y-θconversion means 6 inputs the digital signals S and C from the operation means 3 as X and Y signals to obtain an angle signal. With the digital signals S and C, the amount of offset which the A/D converter has, is compensated so that the error due to the offset of the obtained angle signal is eliminated.
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