Maximum frequency and optimum performance of class E power amplifiers

An analytical method is proposed to discuss class E RF power amplifiers with finite choke inductors. All parameters in these amplifiers can be expressed in terms of circuit-component values and amplifier specifications. The component values of class E amplifiers required to achieve optimum amplification can be directly obtained after the amplifier specifications are fixed. An obvious relationship between the parameters of class E amplifiers with finite choke inductors in optimum performance can be obtained. Hence, the key function of each component in the circuit can be indicated clearly, especially in the case of a finite choke inductor. The finite choke inductor can also be used to compensate for the high intrinsic output capacitance of the active power device to extend operation frequency. To assure optimum performance and safe operation, a criterion is assigned. Based on this criterion and the optimum conditions, a maximum frequency for a transistor safely operating in class E amplifiers can also be obtained