Design of a class E RF power amplifier with shunt capacitance and shunt filter using a modified load network

Class E switching-mode RF power amplifiers have been extensively utilized in contemporary wireless transmitting systems to provide high efficiency and long battery life. The class-E power amplifier with an output network constituted from a parallel capacitor, series inductor, and shunt resonant circuit provides a replacement for the original class E power amplifier with shunt capacitance by offering the same circuit simplicity and performance predictability in addition to wide frequency band capability. This paper presents a new transmission-line load network topology for the class-E power amplifier with shunt capacitance and shunt filter by introducing an alternative method for evaluating the optimum load resistance for maximized efficiency, and integrating a low-pass Chebyshev transforming network for better harmonic suppression. This circuit is first mathematically analyzed and then simulated by means of the ADS software. A prototype power amplifier model is also fabricated based on the ATF-34143 GaAs pHEMT low cost transistor to operate at 1 GHz. Experimental results show that a dc-to-RF efficiency of 61%, output RF power of 23 dBm, and power gain of 11 dB have been obtained at input power level of 12 dBm.