| 摘要 |
PURPOSE:To prevent the effect of external disturbance or temperature change by using a difference voltage across a loop filter whose one end is fixed to a reference voltage as a differential control signal of a differential amplifier provided to the input section of a voltage controlled oscillator. CONSTITUTION:An input data signal 11 and an output clock signal 17 are inputted to a phase comparator 1, and a signal 12 when the signal 11 is leading and a signal 13 when lagging are outputted to a charge pump 2. In receiving the leading signal 12 or the lagging signal 13, the charge pump 2 supplies a current 14 to a loop filter 3 for the time of takes out the current 14. One terminal of the loop filter 3 is connected to the reference voltage V1 and the other terminal is connected to the charge pump 2, the filter 3 integrates an output current 14 and the potential at both terminals is used as differential signals 15, 16, which are inputted to gates of differential transistors (TRs) Q1, Q2 of the voltage controlled oscillator 4. Then a differential output 18 is generated in the TR Q1 to change the phase of the output clock signal 17. Thus, the effect of external disturbance and temperature change is prevented. |
