| 摘要 |
PURPOSE:To provide a phase detecting circuit which can increase the phase detecting range and can improve the resolving power of the phase detection without increasing the capacity of a ROM. CONSTITUTION:This system is provided with the absolute value circuits 22 and 23 which obtains the absolute value ¦a¦ and ¦b¦ and the polarity of the data on two points of an input signal where the phases are different by pi/2 from each other, a circuit 24 which calculates the value ¦b¦-¦a¦, a ROM 26 which previously stores the data showing a phase theta=tan-1 (a/b) in a prescribed range of the input signal with the value ¦a¦ and ¦b¦ defined as the address input, the circuits 251 and 252 which replaces the value ¦b¦ with the value ¦a¦ of the address input of the ROM 26 when ¦b¦-¦a¦<0 is satisfied, and a circuit 30 which outputs the value of the phase theta of the data D read out of the ROM 26 as it is or after the correction of the phase theta if the value of the phase theta of the data D must be corrected. |
