High-efficiency Rf Power Amplifier

This paper does research on the key module-high efficiency power amplifiers-in wireless communication integrated circuit system.In the first place, basic knowledge of conventional power amplifiers are introduced and presented. Then, the efficiency and the normalized output power capability of the conventional power amplifiers are analyzed. At last, the advantages and disadvantages of several conventional power amplifier topologies are compared. In the second place, this paper presents the operation principles of switched-mode power amplifiers, deduces the parameters of the circuit elements under arbitrary duty-cycles and analyzes how the performances of the class E power amplifiers are influenced by the duty-cycles. Meanwhile this paper presents the efficiency and the normalized output power capability of the class E power amplifiers. In the third place, the shunt capacitance is one of the most important parts in the class E power amplifier topologies. With increasing of the operation frequency, the parasitical output capacitance which used to be nonlinear of the MOSFET devices can never be neglected. This paper presents a novel way to design class E power amplifiers with nonlinear capacitance which is entirely composed by the parasitical output capacitance of the MOSFET devices. Finally, the theoretical results deduced in this paper are verified by the simulation based on the packaged LDMOS FET Ericsson PTF10135 spice model, the operation at 200MHz shows very good correlation between the theoretical and the simulated results.