This work aims to create a method for estimating the bandwidth and performance of power amplifiers based on load modulation. This method is designed to assist during the design process and requires an accurate depiction of complex and highly non-linear systems using equivalent models and linear simulations. This approach facilitates optimizations and multiple iterations, which can be challenging to achieve with non-linear simulations. The proposed technique is based on a numerical code that characterizes passive power combiner networks and models the response of active devices, like transistors, to generate significant performance indicators related to the amplifier. This innovative method considers certain physical limitations that cannot be modeled with CADs.