Phase-locked loop circuit comprising voltage-controlled oscillator having variable gain
AssigneeElectronics and Telecommunications Research Institute
InventorsSang Hyun Cho, Hui Dong Lee, Kwi Dong Kim, Jong Kee Kwon, Seung Tak Ryu
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Abstract
A phase-locked loop (PLL) circuit including a voltage-controlled oscillator (VCO) with a variable gain is provided. A phase frequency detector (PFD) detects a phase difference between a reference signal and a PLL feedback signal. A charge pump and a loop filter sequentially process an output signal of the PFD. A VCO has different gains according to a mode transition. A control voltage applied to the VCO is selected from an output signal of the loop filter and an additional control signal according to the mode transition.
Claims14
A phase-locked loop (PLL) circuit comprising:
- a phase frequency detector (PFD) configured to detect a phase difference between a reference signal and a PLL feedback signal;
- a charge pump and a loop filter configured to sequentially process an output signal of the PFD;
- and
- a voltage-controlled oscillator (VCO) configured to have different gains according to a mode transition,
- wherein a control voltage applied to the VCO is determined from an output signal of the loop filter in a first mode and from the output signal of the loop filter and an additional control signal in a second mode.
Dependencies are inferred from the claim text.