To design and model a Class F amplifier and investigate the effect of losses on the efficiency of dc to ac power conversion

Abstract

A detailed design of class-F power-amplifier with a load harmonic network for third harmonic peaking is presented where initially ideal lossless transmission lines and then microstrip lines with losses are used. When the load network is realized using microstrip lines the effect of discontinuities is taken into account. For a network with ideal transmission lines, a 3Ω resistor is used in series with a switch to obtain the predicted efficiency of 75%. Replacing the by microsrtrip lines and neglecting the effect of the discontinuities but with losses included the efficiency was 65.6%. When the discontinuities are included but the network not optimized the efficiency reduced to 63.5%. By tuning the network with discontinuities to obtain the required impedances at the three frequencies the efficiency increased to 67.9%. It can be concluded that the substrate losses have a major effect on the efficiency of power conversion. This shows it’s important to use low loss substrates such as Duroid with a loss tangent is 0.002 where as for PCB it is 0.019 produce higher efficiency of power conversion