FREQUENCY-LOCKING DEVICE AND FREQUENCY-LOCKING METHOD THEREOF

摘要

A frequency-locking device including a digitally-controlled oscillator (DCO) and a comparing unit is disclosed. The DCO is used for generating an output frequency signal. The comparing unit receives a Keep Alive signal or a start of a frame (SOF) from a universal serial bus (USB) and the output frequency signal, and compares the Keep Alive signal or the start of a frame (SOF) with the output frequency signal to generate a calibration signal. Then, the DCO adjusts the frequency of the output frequency signal according to the calibration signal to meet the USB specification for data communication.