Abstract: In a circuit in which a current is supplied to an internal node and in which transistors have their base-to-emitter junctions connected in series between the internal node and a point of reference potential, (m-1) Schottky diodes, poled to conduct current in a direction opposite to that of the "m" base-to-emitter junctions, are connected in series between the internal node and an input terminal; where m is an integer greater than 2. The (m-1) diodes compensate for the change in the base-to-emitter voltages and extend the operating range of the circuit as a function of temperature. Also, the use of two or more diodes connected in series between the input terminal and the internal node decreases the capacitance between the input terminal and the internal node, and reduces the voltage swing at the internal node necessary to turn-on and turn-off the "m" base-to-emitter junctions.
Abstract: A high speed bipolar noninverting current-mode logic AND gate is the basic building block for a current-mode logic family. The AND gate comprises a current steering differential pair of transistors, a pair of dual emitter input transistors, a dual emitter reference transistor, an output resistor and a fixed current source. The conducting state of the current steering transistor pair is so controlled that a logic "one" at the base electrodes of both input transistors produces a logic "one" at an output terminal taken from the collector electrode of the reference transistor. Further, a logic "zero" at both input transistors produces a logic "zero" at the output terminal and finally the condition of a "zero" at one input and a "one" at the other input produces a "zero" at the output.
Type:
Grant
Filed:
December 8, 1975
Date of Patent:
February 8, 1977
Assignee:
Bell Telephone Laboratories, Incorporated