Modeling and simulation of arbitrary ordered nonlinear charge-pump phase-locked loops

The simulation of charge-pump phase-locked loops (CP-PLL) is a challenge within the design. The problem is related to the mixed-signal and nonlinear behavior as well as the existence of high and low frequency functional blocks. Here a methodology is presented for the efficient and accurate simulation and analysis of the transient characteristic. For this, nonidealities like dead-zone, current/timing mismatches, leakage current and the nonlinear voltage controlled oscillator characteristic are considered. Moreover, the proposed technique is applied to CP-PLL systems with arbitrary loop filters by using the solution of the analog parts of the differential equation system and by solving the phase equation of the system with regard to the switching instant of time of the phase and frequency detector.