One potential limitation of the PW-SAF approach is the assumption of continuity and smoothness between the piecewise linear segments. If the VCO characteristics exhibit abrupt changes or discontinuities that cannot be adequately captured by linear approximations, the PW-SAF may introduce errors in the model. Additionally, the accuracy of the PW-SAF heavily relies on the selection of tuning voltage sampling points and the number of intervals chosen, which could impact the overall performance of the model.
Circuit-level HB simulations might still be necessary under certain conditions, such as when dealing with highly nonlinear VCO characteristics that cannot be effectively approximated by piecewise linear models. In cases where the VCO behavior deviates significantly from the linear approximation, circuit-level simulations can provide a more precise representation of the system dynamics. Furthermore, if the VCO array operates in a regime where strong coupling effects or complex interactions between oscillators come into play, circuit-level simulations may be essential to capture the intricate behavior of the coupled system accurately.