摘要 |
A phase-locked loop for generating an output signal including a signal generator arranged to generate an output, a comparison unit arranged to compare the output with a reference signal so as to provide a digital signal, and a loop filter arranged to generate a control signal for controlling the signal generator in dependence on the digital signal. The loop filter includes a proportional path having a digital filter arranged to generate a first component of the control signal for controlling the phase of the output generated by the signal generator, and an analogue integral path arranged to generate a second component of the control signal for controlling the frequency of the output generated by the signal generator. |