DIGITAL PHASE LOCKED LOOP FOR LOW JITTER APPLICATIONS

摘要

A phase locked loop circuit is disclosed. The phase locked loop circuit includes a ring oscillator. The phase locked loop circuit also includes a digital path including a digital phase detector. The phase locked loop circuit further includes an analog path including a linear phase detector. Additionally, the phase locked loop circuit includes a feedback path connecting an output of the ring oscillator to an input of the digital path and an input of the analog path. The digital path and the analog path are parallel paths. The digital path provides a digital tuning signal the ring oscillator that digitally controls a frequency of the ring oscillator. The analog path provides an analog tuning signal the ring oscillator that continuously controls the frequency of the ring oscillator.

主权项

1. A phase locked loop circuit, comprising:
a ring oscillator; a digital path including a digital phase detector, an integral gain device and an integrator; an analog path; and a feedback path connecting an output of the ring oscillator to the digital path and to the analog path.