Optimum design of very high-efficiency microwave power amplifiers based ontime-domain harmonic load-pull measurements

Due to the large expansion of wireless communications, the need for high-ef ficiency power amplifiers has emerged, In mobile communication systems, pow er amplifiers are the most critical elements for the power-dissipation budg et, Thus, the operating conditions of active devices have to be optimized u sing accurate and complementary computer-aided design (CAD) and experimenta l tools, This paper reports two design methods of high-efficiency power amp lifiers. The first one is CAD oriented and based on the substitute generato r technique using the nonlinear model of transistors. The second one is bas ed on a specific measurement system of time-domain waveforms using a modifi ed vector network analyzer, coupled with harmonic active load-pull techniqu es (three active loops). This new setup enables the measurement and optimiz ation of time-domain waveforms at both ports of transistors driven by const ant-wave test signals. These two design methodologies are applied to the op timization of an S-band 1-W class-F GaInP/GaAs heterojunction-bipolar-trans istor power amplifier.