Current-operated circuits and structures

A current-mode OR gate comprising, in combination:

• an output terminal and a common terminal for connection to an output circuit;
• a plurality of switches, each having a conduction path and a control electrode for controlling the conductivity of its path, said conduction paths connected in parallel between said output terminal and a third terminal, said control electrodes serving as input terminals;
• direct current impedance means connected between said third terminal and said common terminal;
• means responsive to an input current of greater than a given value applied to one of said input terminals for closing the switch connected to that input terminal;
• and
• regulator means connected for sensing the potential across said direct current impedance means and responsive to said voltage when it exceeds a given fixed value for establishing between each separate one of said input terminals and said common terminal a shunt path for diverting that portion of the signal current applied to its input terminal which would tend to cause the voltage across said direct current impedance means to exceed further said given value.

A current mode OR gate comprising:

• a plurality of input terminals, a common terminal and an output terminal;
• a plurality of threshold detection circuits, each having a controllably-conductive path connected between said output terminal and a first point of interconnection, each having a control terminal connected to a respective separate one of said input terminals, and each characterized by its controllably-conductive path being substantially non-conductive until the current applied to its control terminal is in excess of a threshold value and conductive in a degree dependent upon the degree of said excess thereafter;
• direct current conductive means connecting said first point of interconnection to said common terminal;
• regulator means for sensing the current flowing through said direct current conductive means and when it tends to exceed a predetermined value, for providing a shunt current path connected at one end to said common terminal and having a second end;
• and
• steering means connected between each input terminal and the second end of said shunt current path for diverting to said shunt current path that portion of the input current applied to any input terminal, which would tend to cause the current flow through said conductive means to increase to a value greater than said predetermined value.