Transceiver for full-duplex transmission of digital signals over a common line

A transceiver inserted between a signal source and a line with at least one ungrounded conductor designed for two-way transmission of digital signals, said conductor being provided with a terminating impedance having a proximal end and a distal end as seen from said signal source, comprising:

• a first pair of emitter-coupled twin transistors with respective first bases, with an inverting and a noninverting first output connected to respective first collectors thereof and with a first input circuit including a connection from one of said first bases to said conductor at said proximal end for picking up an outgoing signal originating at said signal source;
• a second pair of emitter-coupled twin transistors with respective second bases, with an inverting and a noninverting second output connected to respective second collectors thereof and with a second input circuit including a connection from one of said second bases to said conductor at said distal end for picking up a mixture of said outgoing signal with an incoming signal, said first inverting output being directly connected to said second noninverting output at a first junction, said first noninverting output being directly connected to said second inverting output at a second junction, said first and second pairs having a gain ratio substantially suppressing said outgoing signal at said junctions;
• and
• a differential amplifier with inputs respectively connected to said junctions and with an output connected to a signal receiver.