Self-biased feedback-controlled pull-down emitter follower for high-speed low-power bipolar logic circuits

Abstract

The self-biased, feedback-controlled, active-pull-down emitter follower is a very efficient and superior circuit applicable to high-speed low-power bipolar/BiCMOS digital VLSIs. The circuit is effective because the biasing, inverting, level-shifting, and coupling functions are simply merged into a small number of devices and is versatile for logic implementations because it does not need any extra out-of-phase signal from the logic stage, allowing the collector-dotting and emitter-dotting. The push-pull operation of this novel circuit is precisely controlled by a feedback mechanism and results in a remarkable performance enhancement: 2.7x typical simulated pull-down speed and 10x drive capability over the conventional RPD-ECL.