Modeling and design of high-efficiency power amplifiers fed by limited power sources

Recently the non-electromagnetic energy sources and wireless power transfer (WPT) techniques have been used to obtain electromagnetic (EM) energy sources for providing energy autonomy to electric devices when the energy in the environment is insufficient. Typically, this type of systems are composed by a harvester, a DC/RF converter, a WPT interface and a load. Further, in the power stage of the DC/RF converter the energy flow is processed using a power amplifier (PA). This paper proposes a design methodology for a generic PA fed by a limited power source. This methodology extracts the maximum available power of the EPS with the maximum PA efficiency using impedance matching and a novel PA modeling based on its impedance ports (DC and AC). Moreover, models of class-A PA and class-D PA were developed as examples. Furthermore, a Class-A PA was designed using its impedance ports model and the proposed methodology as a proof of concept. The results reflect that the designed PA extracts the maximum available power of the source with its maximum efficiency.