ECL CIRCUIT

PURPOSE: To obtain optimal DC/AC connection to a self-reference front end amplifier for supplying a complementary output signal to a true push-pull output buffer stage by including a biasing/ combining means connected to one of power supplies in a circuit family. CONSTITUTION: The base of a transistor(TR) TDN which supplies a pulldown current necessary for high-speed falling is driven by a signal S via the biasing/ combining block BB included in a front end amplifier 31. In DC, the block BB maintains the potential of nodes M and B in an appropriate value according to the level of logic data applied to a circuit input. The node M is biased so as to define the appropriate voltage threshold value and noise resistance of the front end amplifier 31. Then, in AC, the block BB ensures high-speed signal transmission from node M to node B. The base emitter capacitance CBE of a diode connecting Tr TC is useful to accelerate the conducting of the Tr TDN.