| 摘要 |
PURPOSE:To improve the accuracy of 90 deg. phase shift, by picking up the 1st and 2nd frequency division outputs of a frequency division circuit as an oscillating output having the same period as that of an external synchronizing signal, and different from by 90 deg. in phase. CONSTITUTION:A voltage controlled oscillator 9 is synchronizingly oscillated in a frequency 4n times the external synchronizing signal and the oscillation output is frequency-divided into 1/4n at a frequency division circuit 10. The 1st frequency division output inverted at the 1st and the (2n+1)th pulse of the oscillating output taking each pulse of the external synchronizing signal as a reference, and the 2nd frequency division output inverted at the (n+1)th and the (3n+1)th pulses are generated. The 1st frequency division output and that of the external synchronizing signal are compared 7 in phase, and the output is applied to the oscillator 9 as a control voltage via an LPF8. Thus, the 1st and the 2nd frequency outputs of the circuit 10 are picked up as the oscillating output being the same period as the external synchronizing signal and different from by 90 deg. in phase. |
