Patent ID: 7859343

Claim:
An all-digital phase-locked loop (ADPLL), comprising: a digitally controlled oscillator (DCO) for generating an oscillation signal, comprising at least one delay circuit including at least one digitally controlled varactor (DCV), wherein the DCV comprises a transistor having a gate, a source, a drain, and a substrate, wherein at least one of the gate, the source, the drain, and the substrate is coupled to receive one of two or more voltages, wherein at least one of the two or more voltages is not a power supply voltage or ground; a frequency divider coupled to receive the oscillation signal and to generate a divided frequency signal, wherein a ratio of a frequency of the oscillation signal to a frequency of the divided frequency signal is a predetermined number; a control unit coupled to receive a reference signal having a reference frequency and the divided frequency signal; a coarse tuning part including a counter coupled to the control unit for counting cycles of the oscillation signal during one cycle of the reference signal, a comparator for comparing the counted number of cycles of the oscillation signal during one cycle of the reference signal with the predetermined number, a first successive approximation register (SAR) for generating a first control signal based on a result of the comparing of the counted number with the predetermined number, and a first up/down counter coupled to receive the first control signal for generating a first control word for adjusting the frequency of the oscillation signal; and a fine tuning part including a phase and frequency detector coupled to the control unit for comparing a phase of the divided frequency signal with a phase of the reference signal, a second SAR for generating a second control signal based on a result of the comparing of the phase of the divided frequency signal with that of the reference signal, and a second up/down counter coupled to receive the second control signal for generating a second control word for adjusting the frequency of the oscillation signal.