Phase lock loop circuit
AssigneeNovatek Microelectronics Corp.
InventorChih-Hung Chen
Life of this patent
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Abstract
A phase lock loop (PLL) circuit having a phase frequency detector (PFD), a coarse tune low-pass filter module, a voltage control oscillation (VCO) module and a feedback loop is provided. The PFD compares phases and frequencies of an input signal and a feedback signal. The coarse tune low-pass filter module is coupled to the PFD and used for low-pass filtering a control signal with a gradually narrowed bandwidth to generate a filtered signal. The control signal indicates the comparison result of the input signal and the feedback signal. The VCO module has a first VCO gain and a second VCO gain, and generates an output signal according to the control signal and the filtered signal. The feedback loop provides the feedback signal to the PFD according to the output signal.
Claims17
A phase lock loop circuit, comprising:
- a phase frequency detector, comparing phases and frequencies of an input signal and a feedback signal;
- a coarse tune low-pass filter module, low-pass filtering a control signal indicating the comparison result with a gradually narrowed bandwidth to generate a filtered signal;
- a voltage control oscillation module, generating a first oscillation signal through a first voltage control oscillation gain according to the control signal and generating a second oscillation signal through a second voltage control oscillation gain according to the filtered signal, and generating an output signal according to the first oscillation signal and the second oscillation signal, wherein the second voltage control oscillation gain is higher than the first voltage control oscillation gain;
- and
- a feedback loop, supplying the feedback signal to the phase frequency detector according to the output signal.
A phase lock loop circuit, comprising:
- a phase frequency detector;
- a coarse tune low-pass filter module, coupled to the phase frequency detector, operating with a gradually narrowed bandwidth;
- a voltage control oscillation module, having a first voltage control oscillator coupled to the phase frequency detector, and a second voltage control oscillator coupled to the coarse tune low-pass filter module;
- and
- a feedback loop, coupled between the voltage control oscillation module and the phase frequency detector.
Dependencies are inferred from the claim text.