| 摘要 |
<p>A local generated frequency is brought inot synchronization with a reference frequency using a phase-locked loop (PLL) which is configured to operate in a way to reduce the lock time required to achieve synchronization. The PLL includes a voltage-controlled oscillator (VCO) for generating the local frequency in response to an adjustable input control voltage to the VCO, and a phase detector for adjusting the control voltage according to a lack of synchronization between the local frequency and the reference frequency. Initially, a successive approximation process is performed to rapidly adjust the control voltage applied to the VCO in a direction to reduce the frequency offset of the local frequency from the reference frequency and thereby rapidly move toward synchronization therebetween. The phase detector is then enabled to perform a final adjustment of the control voltage to complete the synchronization.</p> |
