Modeling and Analysis of Class-E Amplifier With a Shunt Inductor at Sub-Nominal Operation for Any Duty Ratio

This paper presents analytical expressions for the sub-nominal operation, which is only the zero current switching (ZCS) condition, of the class-E power amplifier with a shunt inductor at any duty ratio. The duty ratio is considered not only as a design specification but also as an adjustment parameter. In the sub-nominal operation with any duty ratio, both the peak switch voltage and the peak switch current can be set as design specifications due to two more degrees of design freedom in comparison with the class-E nominal amplifier at the fixed duty ratio. Additionally, it is also seen that the duty ratio affects the maximum operating frequency and the output power capability with ZCS condition. A design example of the class-E ZCS amplifier with a shunt inductor under the specifications of peak switch voltage and peak switch current is given. The measurement and a simulation by circuit simulator results agreed with the analytical expressions quantitatively, which show the validity of our analytical expressions.