Motorola Corporation

Ramachandra A Rao

Roger L Hollstein

Frank J Swiatowiec

A high band width logic gate including a basic current switch logic block and emitter-follower output transistors. A switchable active circuit current sink is connected between an internal voltage switching node associated with the current switch logic gate and the emitter terminal of the emitter-follower output transistor. The active current sink is switched between a relatively low conductive state to a relatively high nonsaturating conductive state in order to maintain substantially constant current flow through the emitter-follower output transistor during switching of the logic gate in order to significantly improve AC beta roll off characteristics.

High band width emitter coupled logic gate

A current mode logic circuit providing AND/OR type functions wherein '0' voltage level changes and spikes are substantially eliminated without sacrificing switching speeds by omitting conventional emitter and collector-dotting between the logic input gates and an emitter-follower output stage. The input gates employ diode loads for generating reduced signal swings for driving the output gate. The output gate contains more devices than a single emitter-follower output stage, but the reduced signal swing and a push-pull drive mode for the output gate offsets any increased switching times due to the greater number of devices and thus achieves the overall objectives without any overall sacrifice in switching speed.

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Scottsdale, AZ, United States of America

Ramachandra A Rao