Optimization of A-class power amplifiers in terms of efficiency

Background. Typical A-class power amplifiers usually have low electronic efficiency values, since their operating conditions do not always correspond to the optimal efficiency mode. The Aim of the article is to optimize the efficiency of an A–class power amplifier, in the model of which the output capacity of its transistor is directly taken into account. Methods. For the proposed model of an A-class power amplifier, the waveforms of its current and voltage are obtained, as well as the formula for the parameter that takes into account the output capacitance of its transistor. Results. For the considered A-class power amplifier, the efficiency and normalized impedances of its loads at the fundamental frequency and its harmonics are calculated. The formula for recalculating the normalized and non-normalized values of the load impedances of the amplifier is also obtained. Conclusion. Using calculated data and simulation results, the values of drain efficiency close to the theoretical limit for the A-class power amplifier were achieved in the model of the A-class power amplifier. Moreover, the developed layout has the same linearity and broadband characteristics as those of A-class amplifiers. The possibility of using the proposed efficiency optimization technique in matched monolithic amplifiers has also been confirmed.