Fast automatic gain control (AGC) arrangement provided in an RF receiver which receives data from high-rate multiple transmission channels, in which the AGC amplifier (1) is controlled by a control voltage read from a random access memory RAM (2) which renders it possible to repeat once or several times consecutively the measurement and the correction of the output voltage of the amplifier during the period of time in which a channel is in use, the control voltage correction signal being processed in a circuit (6-10) for measuring and comparing the output voltage of the AGC amplifier to which a read-only memory (PROM)(11) is added which provides a means for correcting the imperfections of the amplifier (1) and of said measuring and comparison circuit.