(under subclass 64) Subject matter comprising the interfacing between an emitter-coupled logic circuit and a transistor-transistor logic circuit.
(1) Note. An emitter-coupled logic device is a nonsaturated bipolar logic device in which the emitters of the input logic transistors are coupled to the emitter of a reference transistor.
(2) Note. A transistor-transistor logic device has a forward-biased input transistor which is responsive to an input logic signal at each of its one or more emitters and with its collector being directly coupled to the base of an output transistor. In TTL, the base-collector junction of the input transistor (usually a multiemitter type) remains forward biased and in the saturation region when the circuit is in either the "on" or "off" condition.