| 摘要 |
PROBLEM TO BE SOLVED: To put the loop back into a blind sector by making the output of a frequency detector get saturated speedily when a specific frequency difference is exceeded and allowing the frequency detector to drive the loop with the full power when a voltage-controlled oscillator is not within the band. SOLUTION: A phase sampler 26 samples the phase of an input signal and a phase correcting generator 32 generates a correction phase based on oversampling. Further, a subtracter 28 corrects the output of the phase sampler 26. The output of this subtracter is connected to a rotating direction/frequency detector block. The output of this block shows a rotating direction and a beat frequency. During operation, a general oversampling rotational frequency detector measures a frequency error of the signal by sampling a reference signal at fREF. Phase rotation of successive samples is found and an oversampling phase error item is removed for phase sample correction. |
