POWER AMPLIFIER HAVING MULTIPLE SWITCHED STAGES

摘要

A power amplifier for a plate load of an AM, RF transmitter includes plural switching stages each powered by a DC source. Each stage is switched from non-sourced to saturation in response to the amplitude of an analog source exceeding a threshold amplitude for the stage; each stage has a different threshold. The thresholds and analog source are arranged so that responses derived between output terminals of the stages change between zero and predetermined amplitudes as the source amplitude changes relative to the thresholds of the different stages. The responses of the different stages are summed. A triangular wave having a small constant maximum amplitude relative to the analog source maximum value effectively changes the threshold of each stage. From time to time the thresholds of different stages are changed so that at different times different stages are in non-sourced and conducting for the same amplitude of the modulating source, while providing the same summed response for the same amplitude of the modulating source.