Phase-locked loop systems using adaptive low-pass filters in switched bandwidth feedback loops
Methods and systems directed toward a PLL circuit including a local lock detector receiving an error signal and providing a lock signal, and a charge pump for receiving the error signal and providing a charge signal. A loop filter provides a first loop filter bandwidth and a second loop filter bandwidth. The loop filter includes a first low-pass filter configured to receive the charge and lock signals, alter a filter characteristic in response to the lock signal, and provide a first filter signal. The loop filter includes a second low-pass filter configured to receive the first filter and lock signals, alter a filter characteristic in response to the lock signal, and provide a loop filter signal. The PLL circuit includes a VCO for receiving the loop filter signal and providing an output signal, and a divider for receiving the output signal and dividing it to provide the reference signal.
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Rohini Amrita Ragu Benedykt Ron
Abhyankar Deshpande Sridhar Mika Osgood