12.8-ps 1.0-mW charge-buffered active pull-down NTL circuit

An NTL circuit with a charge-buffered active-pulldown emitter-follower stage is described. The circuit utilizes the diffusion capacitance of a charge-storage diode (CSD) as the coupling element between the common-emitter node of the switching transistors and the base of an active-pull-down n-p-n transistor to generate a large dynamic current for the pull-down transistor and to provide a speedup effect on the switching logic stage. Implemented in a 0.8- mu m double-poly trench-isolated self-aligned bipolar process, unloaded gate delays of 12.8 ps/1.0 mW, 15.4 ps/0.71 mW, and 18.0 ps/0.53 mW have been achieved.<
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