A new method for the analysis and design of the class E power amplifier taking into account theQ_Lfactor

Most previous papers on class E power amplifier are based on an analysis method proposed by Raab in which it is assumed that the
Q_L
factor of the series-tuned circuit is high enough that the output current is essentially a sinusoid at the carrier frequency. In this paper, a new method for the analysis and design of a class E amplifier is presented and implemented for the case of the series-tuned, shunt-capacitor class E configuration, in which the assumption of infinite
Q_L
is eliminated. The amplifier performance equations are obtained by finding the steady-state initial conditions of the load-network state variables. The design requirements are then imposed on the resulting equations. This leads to a nonlinear system of design equations which is solved for the design values using numerical optimization methods. For values of
Q_L
less than 15, the differences between the design values obtained using this method and those given by Raab become gradually more significant. The performance curves given in this paper show clearly that the overall amplifier performance is strongly affected by
Q_L
. Therefore, this method of analysis and design is useful because it provides accurate design values which ensure optimum and safe performance for the class E amplifier even in cases of low
Q_L
, it provides quantitative criteria for the usual tradeoffs concerning
Q_L
, and it makes the amplifier performance more predictable.