| 摘要 |
PURPOSE:To generate a clock, which can send a transmission signal of less jitter to a home device and has less jitter, in an intra-office terminating equipment by providing a master clock oscillator, a frequency division ratio designating circuit, a variable frequency dividing circuit, or the like. CONSTITUTION:The master clock from a master clock oscillator 1 has the frequency normally divided by N in a variable frequency dividing circuit 2 to generate an output clock, and this output clock is outputted to a fixed frequency dividing circuit 3. The circuit 3 outputs the inputted clock to a phase comparing circuit 4 after frequency division, and the circuit 4 compares its phase with the phase of the reference clock extracted from a network. The frequency division ratio of the circuit 2 is changed by a frequency division ratio designating circuit 5 in accordance with the comparison result to synchronize the phase. In this case, a frequency fM of the master clock is set to satisfy fM=f0XN+ or fM =f0XN- where f0 is the nominal frequency of the output clock. Thus, the frequency in occurrence of jitter is reduced to improve the circuit characteristic. |
