Sub-30-ps ECL Circuit Operation at Liquid-Nitrogen Temperature Using Self-Aligned Epitaxial SiGe-Base Bipolar Transistors

We report the first operation of ECL circuits at liquid-nitrogen temperaure using self-aligned epitaxial SiGe-base bipolar transistors. A minimum ECL gate delay of 28.1 ps at 84 K was measured, and is essentially unchanged from its room-temperature value of 28.8 ps at 310 K. This delay number was achieved under full logic-swing (500 mV) conditions and represents an improvement of greater than a factor of 2 over the best reported value for 84-K operation. Lower power ECL circuits have switching speeds as fast as 51 ps at 2.2 mW (112-fJ power-delay product) at 84 K. These results suggest that silicon-based bipolar technology is suitable for very high-speed applications in cryogenic computer systems. © 1991 IEEE