Non-linear state space averaged modeling of a 3-state digital phase-frequency detector

A non-linear state space averaged model of a digital 3-state phase-frequency detector (PFD) simulates large signal phaselock loop transients 2500 times faster than cycle-by-cycle models. The model is easily linearized about steady state phase error to also support common frequency domain design methods. The VCO and reference are modeled in phase space. The heart of the PFD model is a resettable integrator. The model is implemented in SpectreHDL. An all-Verilog model simulating every cycle of operation calibrated the SpectreHDL model.