Abstract: A digital phase-locked loop (PLL) includes a time-to-digital converter (TDC) and a digitally controlled oscillator (DCO). The DCO generates a PLL clock signal and various sampling clock signals that are mesochronous. The TDC samples a phase difference between a reference clock signal and a frequency-divided version of the PLL clock signal based on the sampling clock signals and various enable signals. The enable signals are generated based on a calibration of the digital PLL. Each enable signal is associated with a sampling clock signal and indicates whether the associated sampling clock signal is to be utilized for sampling the phase difference. Further, the TDC generates control data indicative of the sampled phase difference. The DCO generates the PLL clock signal and the sampling clock signals based on the control data until the digital PLL is in a phase-locked state.

Abstract: A calibration system of a digital phase locked loop (DPLL) includes a calibration circuit and a digitally controlled oscillator (DCO). The calibration circuit is configured to receive an input signal and a feedback signal, and generate a digital signal, based on a frequency of the input signal, a frequency of the feedback signal, and an input bias code. The DCO is configured to receive the input bias code and the digital signal, and generate a bias signal based on the input bias code. The DCO is further configured to generate an analog signal based on the bias signal and the digital signal, and generate the feedback signal such that the frequency of the feedback signal is based on an amplitude of the analog signal.