A new method to design high efficiency power amplifier using dual-band transformer

This paper presents a novel technique to design harmonic tuned power amplifier. The proposed approach is based on the combination of three-section dual band transformer and dc biasing line. With this compact structure, fundamental impedance matching and harmonic control are achieved simultaneously. This method abandons the use of additional shunt stubs besides the dc biasing line so that the design procedure can be simplified and the size and complexity of the harmonic tuned power amplifier can be reduced. For demonstration, a power amplifier working at 2.14 GHz is designed and fabricated. A maximum drain efficiency of 82% is achieved by measurement.