FREQUENCY CONTROL OSCILLATOR FOR HIGH-FREQUENCY PHASE LOCK LOOP

摘要

PURPOSE: To generate a clock signal with a high frequency in matching with a frequency of an input signal, such as a digital data signal sent via an optical fiber. CONSTITUTION: A ring oscillator 102 generates a 2N-phase reference clock signal having a reference frequency of fO, where N is a positive odd integer being at least 3. The 2N reference clock phase signal has phase points distributed uniformly. A waveform generator 104 generates a 2N-phase control signal, having a frequency |fM| corresponding to a difference between a frequency of an input signal and a reference frequency of fO. A frequency controlled oscillator(FCO) 110 generates an output clock signal having an output frequency equal to fO+fM. The frequency controlled oscillator modulates each reference phase signal by a corresponding 2N control phase signal and couples modulated reference phase signals which are obtained as a result to generate the output clock signal.