Design of High Efficiency Broadband Continuous Class-F Power Amplifier Using Real Frequency Technique With Finite Transmission Zero

In this paper, a new methodology using a distributed ladder structure with finite transmission zero at finite frequencies is proposed for designing a broadband high-efficiency continuous Class-F (CCF) power amplifier (PA). The approach of realizing finite transmission zeros in Richard domain using Real Frequency Technique is first presented. By applying the proposed approach, the characteristics of the driving point impedance (DPI) of the proposed structure can be deduced and obtained in theory. Furthermore, the synthesis methods in Richard domain are extended to synthesize the DPI of the proposed structure. Four types of distributed elements are investigated to synthesize the DPI of the proposed structure. This proposed structure can improve the performance of the CCF PA when the bandwidth approaches an octave as the finite transmission zero can be used to control the second harmonic impedance of the lower frequency which is near the upper frequency of the operation band. To verify the validity of the proposed method, a broadband high-efficiency CCF PA working from 1.15 to 2.2 GHz is designed. Experimental results show that the fabricated PA achieves 11.3-13.7 dB power gain and 40.5-43.2 dBm output power in the operation band. And the PA has also achieved a high-efficiency characteristic of 70%-83% drain efficiency (DE) over the whole operation bandwidth.