Emitter coupled logic circuit.

摘要

ECL (Emitter Coupled Logic) circuit is improved to increase its ability to drive a large capacity load (CL) to drive a large fan-out circuit, and the power consumption per gate is reduced. The output circuit (OB1) of the ECL circuit is provided with an emitter follower transistor (T6) of which current is detected by a detecting transistor (T7). A current control transistor (T8) is provided to charge up quickly the load capacitance (CL) under the control of the detecting transistor (T7). So the voltage build down of the output signal is especially improved. One of the emitter follower transistor (T6) and the current transistor (T8) is always cut off when the other is in a conductive state. So the current running through the circuit is reduced.