Abstract: A distortion correction arrangement for a power amplifier which uses transistors is described. Biasing circuits are coupled to the transistor for biasing a transistor into a low-distortion conduction condition. The conduction condition of the transistor changes in response to the signal power being handled. Changes in signal power may therefore change the conduction condition to one of higher distortion. Bias control circuits are coupled to the transistor and to the bias circuit for controlling the bias in response to the signal power being handled. In a particular embodiment of the invention, the bias control circuits additionally respond to the rate of change of the signal power.

Abstract: Television broadcast transmitters are often operated at remote sites and must be remotely controlled. The transmitters often include exciters driving high-power amplifiers. The exciters and high-power amplifiers produce incidental phase modulation of the broadcast signals. An exciter for generating modulated carrier signals at a television video carrier frequency may include compensation for incidental phase modulation in the exciter itself and in the following amplifiers. Such an exciter includes a first modulator for modulating video onto an IF carrier, which is coupled through a power splitter to a second modulator. The second modulator is switched at a frequency equal to the sum of the video and intermediate frequencies to produce the desired modulated carrier. The output of the power divider is coupled to an envelope detector which reconstitutes the video.