Look-ahead input buffer and dynamic load sensing scheme for 3.3 V ultrafast BiCMOS SRAMs

Abstract

Achieving fast access time at low voltage and low power is still a demanding task for high density SRAM. Although some previous BiCMOS designs operate at 3.3 V, the access time is usually slower than at 5 V. The speed is mainly dependent on the I/O interface conversion and delay due to long data lines. We developed a look-ahead input buffer to reduce the speed delay at the input stage and a dynamic load sensing scheme to minimize the sensing delay due to long data line. A 3.3 V 1 Mbit(l28K x 8) SRAM is designed to achieve 4.5 ns access time under typical conditions using 0.5 /spl mu/m BiCMOS technology.