Design of a Miniaturized Class F Power Amplifier Using Capacitor Loaded Transmission Lines

AbstractIn this paper, a new method to decrease the dimensions of the microstrip structures and reducing the overall size of the class F amplifiers is presented. First, by using the PHEMT transistor with a conventional harmonic control circuit (HCC), a low-voltage class F amplifier in the L band frequency at the operating frequency of 1.75 GHz is introduced, which named primitive class F power amplifier. Then, this amplifier is optimized by using capacitor loaded transmission lines (CLTLs). The measurement results of the amplifier show that by using the CLTL structure, the overall size has been reduced 85% (0.23 λg × 0.17 λg). The maximum power-added efficiency (PAE) of the power amplifier is about 77.5 % and the power gain which has been reached to 18.33 dB. The desirable features of this power amplifier, along with its very small size, make this power amplifier a good choice to use for the global system for mobile communications.