A digital PLL in uses pulse width detection to provide frequency/phase error correction for a DCO. A pulse width detector is implemented using fine and coarse detection circuits which provide selectable fine and coarse detection granularity. Both the fine and coarse detection circuits use a number of...http://www.google.com.au/patents/US6005425?utm_source=gb-gplus-sharePatent US6005425 - PLL using pulse width detection for frequency and phase error correction
