AN 8-NS 256K ECL SRAM WITH CMOS MEMORY ARRAY AND BATTERY BACKUP CAPABILITY

The authors describe the first high-performance, high-density ECL SRAM (emitter-coupled-logic static random-access memory) compatible with battery backup techniques. The 256K device has a measured access time of 8 ns. Fabricated in a 0.8-μm BiCMOS process, the chip uses 117-μm2, full-CMOS, six-transistor memory cells and measures 6.5 × 8.15 mm2. The design methodology described here illustrates the extent to which bipolar devices can be integrated into the periphery of a CMOS memory array. This integration was achieved through the use of a novel sensing scheme which provided three stages of bipolar differential sensing, with the first stage of sensing taking place directly on the bit lines.