| 摘要 |
A phase lock loop includes a voltage controlled oscillator (VCO), a phase comparator for comparing the phases of the output of the VCO and a reference signal, a charge pump circuit, including a plurality of current sources, for supplying a control voltage by charging or discharging a capacitor based on the outputs of the current sources, and a current source controller for controlling the current output of the current sources by a n-bit current control signal. Charge current and discharge current by the charge pump circuit are controlled in n bits so that a rapid synchronization during lock-in and a low jitter after lock-in can be obtained.
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