# Alternative Categorization of Radio Frequency Power Amplifier for Generalized Design Insights
## 4 Generalized Design Approach
### Vertical Flow
They  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Category Domain** & **Category Type** & **Sub-Category Type** & **Class/Technique** & **Typical Efficiency** & **References** \\ \hline \multirow{10}{*}{Time} & \multirow{5}{*}{Amplifier Class} & Overlapping & Class A & 25–30\% & [4; 12] \\ \cline{3-5}  & & Overlapping & Class B & \textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}}\) \\ \cline{3-5}  & & Overlapping & Class C & \textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}\textasci{}}\) \\ \cline{3-5}  & & Non-Overlapping (ZVS) & Class E & 60–85\% & [4; 19; 24] \\ \cline{3-5}  & & Non-Overlapping (Harmonic Tuned) & Class F & 70–85\% & [4; 22; 44] \\ \cline{3-5}  & & Overlapping & Class J/B Continuum & 65–80\% & [23; 28] \\ \cline{3-5}  & & Non-Overlapping & Continuous Class E & 65–75\% & [34; 35] \\ \cline{3-5}  & & Non-Overlapping & Continuous Class F & 65–75\% & [29; 30] \\ \cline{3-5}  & & Overlapping & Continuous Class AB & 55–65\% & [31] \\ \cline{3-5}  & & Non-Overlapping & Continuous Class X & 60–70\% & [32] \\ \hline \multirow{2}{*}{Frequency} & \multirow{2}{*}{Design Approach} & \multirow{2}{*}{Step Approach} & Tunable Matching (e.g., varactors, banks) & 60–75\% & [25; 26; 27] \\ \hline \multirow{5}{*}{} & \multirow{5}{*}{Design Technique} & Continuous & Class J, F, X, AB, E & \multirow{2}{*}{60–75\%} & \multirow{2}{*}{[28; 29; 30; 31; 32; 34; 35]} \\  & & Approach & continuum & & \\ \hline \multirow{2}{*}{} & \multirow{2}{*}{Design Technique} & \multirow{2}{*}{Analytical Design} & Filter-based Matching & \multirow{2}{*}{Class-dependent} & \multirow{2}{*}{[36; 38; 39]} \\  & & & Network & & \\ \hline \multirow{5}{*}{} & \multirow{5}{*}{Real Frequency Technique} & Impedance & \multirow{2}{*}{Trajectory Synthesis} & \multirow{2}{*}{Class-dependent} & \multirow{2}{*}{[37; 41; 43]} \\  & & & & & \\ \cline{1-1} \cline{3-5}  & & & & & \\ \cline{1-1} \cline{3-5}  & & & & & \\ \cline{1-1} \cline{3-5}  & & & & & \\ \hline \multirow{5}{*}{} & \multirow{5}{*}{Load Modulation} & Adaptive/Tunable & \multirow{2}{*}{60–75\%} & \multirow{2}{*}{[46]} \\  & & Load Matching & & & \\offer advantages in terms of size, consistency, and performance but have limitations in terms of customization and power-handling capabilities. In essence, the choice between these implementations depends on the specific requirements of the RFPA, including factors such as performance goals, cost constraints, and the desired level of integration. It is essential to consider these options carefully to design RFPs that meet the intended application's needs effectively. On a similar note, while exploring RFPA design, particularly in the medium frequency (MF: 0.3 MHz-3 MHz), high frequency (HF: 3 MHz to 30 MHz), or very high frequency (VHF: 30 MHz to 300 MHz) bands, the practical option often narrows down to utilizing lumped/COTS components. This is because the traditional transmission line becomes impractically large at relatively low frequencies. In the same context, the choice of transistor type also depends on the specific application. For example, silicon-based BJT (bipolar junction transistor) power transistors do not require negative voltages for biasing, whereas GaN (gallium nitride)-based transistors typically do.