WIDE-LOCKING RANGE PHASE LOCKED LOOP CIRCUIT USING ADAPTIVE POST DIVISION TECHNIQUE

摘要

A wide-locking range phase locked loop circuit includes a decision unit and a closed loop connection comprising a phase frequency detector, a charge pump, a loop filter, a voltage controlled oscillator, and a multi-modulus divider. The decision unit receives a phase difference signal outputted from phase frequency detector and the control voltage outputted from the loop filter and determines to select a specific divisor form the plurality of divisors provided by the multi-modulus divider if the phase difference signal indicates an unlocked state and the control voltage is not within a standard voltage operation range.