US Patent 7898305 PLL circuit

A PLL comprises a current-controlled oscillator (18) for generating an output clock signal based on a current signal generated based on a phase difference between a reference clock signal and a feedback clock signal, a current source (28), and an initialization switch (26) for performing an open/close operation based on the initialization signal, the initialization switch being inserted in series to an input terminal of the current-controlled oscillator (18) and the current source (28).