Abstract text

Apparatus includes an equalizer having a signal input, a control input and an output; a controllable power supply having a control input and an output, the input of the controllable power supply being coupled to the output of the equalizer; a power amplifier having a main signal input, a power supply input, and an output, the power supply input being coupled to the output of the controllable power supply; and a controller having first and second inputs and an output, the first input being coupled directly or indirectly to the output of the controllable power supply, the second input being coupled to a node upstream of the equalizer, and the output being coupled to the control input of the equalizer; the equalizer being configured to apply equalisation to an envelope signal received at its input and to provide a resulting equalized envelope signal at its output, the controllable power supply being configured to provide a power signal at its output based on the equalized envelope signal received at its input, the power amplifier being configured to utilize power received at its power supply input to provide on its output a modulated transmission signal representative of a signal received at the main signal input, and the controller being configured to compare input signals received at its first input to signals received at its second input, and to utilize the results of the comparison to configure the equalizer to correct for variations in the response of the controllable power supply at different frequencies.