a second amplifier which is connected to the second terminal 14 and the gain of which is 1 k the output signals of the two signal amplifiers contained in the hybrid circuit 21 b are added and supplied to a further signal amplifier which delivers the signal amplified with a gain factor g the signal coupled out of the hybrid circuit 21 b is also supplied to a summation node 22 and added to the transmit signal before the signal input of the signal amplifier 20 fig1 shows a further embodiment of the driver circuit 1 according to the invention in the embodiment shown in fig1 the complex terminating impedance 15 the impedance of which is is connected between the signal amplifier 20 and the primary winding 12 1 of the transformer 12 the filter 11 shown in fig1 is not provided in an alternative embodiment so that the signal output of the signal amplifier 20 is connected directly to the terminating impedance 15 the tap for a hybrid circuit 21 c is made between the first terminal 13 of the primary winding 12 1 of the transformer 12 and a node 25 the signal picked up at the node 13 is delivered by a signal amplifier with the gain to a summation node provided in the.