Monolithically integrated telephone circuit for driving wide-band telephone lines for data transmission

The invention relates to a monolithically integrated telephone circuit for driving wide-band telephone lines and transmitting digital data at a very high frequency. The telephone circuit is powered from a battery DC supply providing a pair of voltage references. The telephone circuit includes an output circuit portion including a pair of differential output stages, each having a pair of inputs and being connected with its output to a respective lead of a two-wire telephone line. The telephone circuit also includes a device for deriving a reference voltage from the supply voltage, and includes a low-voltage supply network which is input a DC signal and produces a voltage reference to be added to the reference voltage for delivery to one input of each output stage. The other input of each stage receives an AC signal in order to present at the circuit output a suitable AC+DC differential voltage for driving the telephone line.