I. Introduction
The benefits of power amplifiers (PA), where two or more active devices (branch PAs) are allowed to interact with each other, such as Doherty or Chireix outphasing, have been widely exploited and adopted in the telecommunication industry [1]. Historically, these PAs have been designed to operate with a single input where additional components ensure the correct signal conditioning for each of the branch PA. The proliferation of modern DSP capabilities opens the possibility of generating individual drive profiles for each device and creates a space where each branch PA can be driven independently. Several recent publications were dedicated to investigating PAs with such drive conditions. [2]–[4]. The papers implicate that some form of LUT is employed in the solution for signal generation. However, the LUT extraction or optimisation method was not described in great detail. This work focuses on deriving a system-level PA characterisation method, which allows to create a suitable drive profile targetting and maximising specific goals such as efficiency, constant gain or linearity. The method was demonstrated for an outphasing PA, where different drive strategies, here referred to as shaping functions, were evaluated with emphasises on the subsequent linearisation using DPD.