| 摘要 |
PURPOSE:To perform stable operation to noise, by detecting the synchronous condition with the output of the differential circuit forming high band filter, in response to the input and output difference of the low pass filter in phase locked loop. CONSTITUTION:The low frequency component obtained at the output of the phase comparator 2 in the impulsive noise included in the input signal f1 is the first input signal a of the differential amplifier 7, it passes through the low pass filter 3 to be the second input signal b and they are in phase. Accordingly, only high frequency component is included in the output of the differential amplifier 7. But, the high frequency component is reduced for the energy much with the low pass filter 3 and the detection voltage out of synchronism produced at the rectifying circuit 8 is slight. Thus, the malfunction due to noise is blocked and stable operation can be made. |
