Generalized Design Considerations and Analysis of Class-E Amplifier for Sinusoidal and Square Input Voltage Waveforms

In this paper, analytical expressions and design equations are presented for a class-E amplifier with MOSFET nonlinear drain-source capacitance and linear gate-drain parasitic capacitance, along with external linear shunt capacitance. The class-E amplifier characteristics are presented as functions of the ratio of the sum of the external linear shunt capacitance and the MOSFET linear gate-drain capacitance to the MOSFET drain-source junction capacitance when the switch voltage is zero. Although the effect of the MOSFET linear gate-drain capacitance is similar to that of the external linear shunt capacitance on the design of the class-E amplifier with a square input voltage, the difference between their effects should be considered for the sinusoidal input voltage, which is one of the most important suggestions in this paper. Additionally, analytical expressions of the output power capability is given, which is considerably affected by the external linear shunt capacitance. Two design examples are presented, taking into account as design specification the output power of 8.7 W and the operating frequency of 4 MHz, along with the PSpice-simulations and experimental waveforms.