6.5 Even-Harmonic Class E

The well-defined analytic solution was based on an assumption of the even-harmonic resonant conditions when the finite dc-feed inductance and parallel capacitance are tuned on any even-harmonic component [22]. The load network of an even-harmonic Class E is shown in Fig. 6.13 where, to compensate the required phase shift caused by the preliminary choice of particular load network parameters, the series capacitor Cx is needed. The value of this capacitance can be found from the consideration of two fundamental voltage quadrature components across the switch given by Eqs. (6.56) and Eqs. (6.57).

Since, for an even-harmonic Class E, the dc-feed inductance is restricted to values that satisfy an even-harmonic resonance condition and it is assumed the fundamental voltage across the switch and output voltage across the load have a phase difference of TT/2, the two unknown parameters can be set in this particular case as

Figure 6.13: Equivalent circuit of the even-harmonic Class-E power amplifier

where n = 1, 2, 3,

The third parameter p can be found using an optimum condition given by Eq. (6.2) as

The dc supply current IQ can be found from Eq. (6.50) when L _b = 0 by

As a result, the normalized steady-state collector voltage waveform for ? ? wt > 2 ? and current waveform for period of 0 ? wt > ? are

Fig. 6.14 shows the normalized (a) load current and collector, (b) voltage, and