A SELF-BIASED FEEDBACK-CONTROLLED PULL-DOWN EMITTER FOLLOWER FOR HIGH-SPEED LOW-POWER BIPOLAR LOGIC-CIRCUITS

A feedback-controlled active-pull-down emitter follower that is self-b iased at a low steady-state current and allows the collector dotting a nd emitter dotting is proposed for high-speed low-power bipolar/BiCMOS digital logic circuits. The push-pull operation of this emitter follo wer is precisely controlled by a feedback mechanism and does not requi re any extra out-of-phase signal other than the emitter-follower input from the logic stage. Simulation results based on a 0.5-mum advanced Si-bipolar technology show that the pull-down delay and drive capabili ty of a loaded 1-mW feedback-controlled pull-down ECL gate are improve d to the pull-up levels, 2.7 and 10 times better than those of the con ventional resistor-pull-down ECL circuit, respectively.