All electronic interface for telephony system

DETAILED DESCRIPTION Therefore, it is an object of this invention to provide an interface circuit that interconnects tip and ring conductors from a subscriber's telephone line and a central switch and that is free of electromechanical relays.
Another object of this invention is to provide an interface between subscriber conductors and a telephone switch that provides signal concentration that is free of electromechanical relays.
Yet another object of this invention is to provide an interface between a subscriber's telephone conductors and a telephone switch that includes a line circuit that is free of electromechanical relays.
Yet still another object of this invention is to provide circuitry for use in a telephone switching network that signals hook switch status and dial pulses and that is free of electromechanical relays.
Yet still another object of this invention is to provide circuitry and an interface between subscriber telephone lines and a telephone switch that provides ringing signals and that is free of electromechanical relays.
Yet still another object of this invention is to provide interfacing circuitry between subscriber telephone lines and a telephone switch that is adapted for large scale integration manufacture.
In accordance with this invention, the interfacing circuitry between a telephone switch and subscriber telephone lines comprises a solid state, bilateral current gate circuit in place of electromechanical relays.
Generally, the bilateral current gate includes a plurality of diodes connected to provide input and output junctions that define parallel, unidirectional current paths including the diodes and balance point junctions that connect to terminals between which the telephone signals are to pass.
Other circuitry produces a bias current to forward-bias the diodes and enable the transfer of signals between the balance point junctions without any significant signal attenuation and without signal distortion.
This invention is pointed out with particularity in the appended claims