a controllable amplifier is disclosed . the amplifier includes two current paths which couple an input to an output of the controllable amplifier . each current path has a respective transistor which is connected as source follower . one of the two current paths is designed to be controllable . it is thus possible to adjust the attenuation and hence the overall gain of the source / follower circuit as a function of a set value for the overall gain . the circuit can be used as a variable gain amplifier , or as a programmable gain amplifier , in radio - frequency transmitters .