Effect of gate‐to‐drain and drain‐to‐source parasitic capacitances of MOSFET on the performance of Class‐E/F ₃ power amplifier

Abstract

In this study, the Class-E/F 3 power amplifier with linear gate-to-drain and nonlinear drain-to-source capacitance is proposed. The analysis for the effect of the parasitic capacitance in the mixed mode Class-E/F 3 with square and sinusoidal gate-to-source voltage has been done. Most of the design equations in this study do not have analytical solutions, and the numerical analyses are used. As can be seen, there is little difference between the results related to the sinusoidal and square gate-to-source voltage. So, only the simulation and experimental result for Class E/F 3 with square gate-to-source voltage at operating frequency of 4 MHz has been done. The results in this study indicate that it is important to consider the effect of the MOSFET gate-to-drain capacitance for achieving the ZVS/ZDS conditions in the Class-E/F 3 power amplifier. The PSpice simulation and measured results are agreed with the analytical expressions, which show the validity of the presented analytical expressions. Finally, the waveforms of Class E/F 3 are compared with equivalent waveforms of Class-E power amplifier, in order to indicate its advantages.

60 W Class-E/F3 Switching Power Amplifier With an Improved Second Harmonic Distortion of −49 dBc

“…The Class-E/F 3 SPAs in [12] and [13] showed high efficiency of 93.45% and 95.45%, and moderately low THD of 4.35% and 5.1% at 4 MHz, respectively. [14] proposed a Class-E/F 3 SPA that has decreased maximum switching voltage by analyzing the gate-to-drain and drain-to-source parasitic capacitors. The Class-E/F 3 SPA showed high efficiency of 95% with a moderately low THD of 4.86% at 4 MHz.…”

Design of broadband Class EF power amplifier based on low-pass filter matching structure

“…The hybrid class EF PAs presented in [20] have received more and more attention recently for which they have the advantages of both class E and class F PAs. The class EF PAs absorb the soft switching characteristic of class E that enables it to achieve 100% drain efficiency while having a low peak drain voltage that is similar to that of class F PAs [21,22,23]. However, due to the influence of the output capacitance of the transistor, the class EF PAs often cannot have a wider bandwidth at higher frequencies [24,25].…”

High-efficiency class E/F₃ power amplifiers with extended maximum operating frequency

“…Whereas, due to the tuning requirements [6,7] and the lack of a simple circuit implementation, e.g., [8], the class-F/F −1 PA also has performance limitations. Based on the advantages and disadvantages in class-E PA [2,3,4] and class-F/F −1 PA [5,6,7,8], it is of great significance to combine the two high-efficiency PAs and present a new PA mode of operation: class-E/F 3 PA [9,10,12,13,14,15], which not only realizes a relatively simple structure, but also reduces the peak voltage V max [9,10]. However, in the class-E/F 3 power amplifier, the optimum shunt capacitance (C) decreases with the increase of the maximum operating frequency (f max , is defined as the maximum frequency at which the device output capacitance C out can provide the shunt susceptance B opt required for optimum operation [11]) for the prescribed output power P 0 and DC supply voltage V DS [12,13].…”