An Active Load-Pull Technique to Emulate Outphasing Power Amplifiers

A general measurement-based design methodology for outphasing transmitter architectures is presented. The emulation technique allows to predict the full real world performance of the outphasing scheme without requiring to fabricate the complete power amplifier (PA). Simply, iterative active load-pull measurements of a single branch PA together with the Sparameters of the output combiner are needed. The method determines the authentic dynamic loading condition of both branch PAs by revealing the internal interactions between the nonlinear active devices. Thereby, the insight into the dynamics of load modulation during the outphasing operation provided by the technique, allows PA designers to optimize circuit performance. The design methodology is demonstrated by emulating an outphasing scheme at 2.14 GHz operated in pure-and mixed-mode.