7000-GATE MICROPROCESSOR ON SOS - PULCE

An n-channel MOS LSI microprocessor integrating 20 000 transistors on a chip has been realized on a sapphire substrate utilizing the Coplanar-II process. It contains ALU, shifters, and 44 registors which are combined to three 16-bit buses. By utilizing three types of threshold voltage for load transistors, 28-percent reduction in power dissipation is achieved. The minimum cycle time is 200 ns. By using the Coplanar-II process, anomalous leakage currents due to parasitic transistors at the sides of island are suppressed. It is found that the silicon-on-sapphire (SOS) version operates 2.3 times faster than the bulk-silicon version, which is mainly explainrd by the parasitic capacitance ratio. Parallel-plate approximation in calculating a wiring capacitance results in an underestimate by a factor of 60 compared with taking the two-dimensional effect into account. Copyright © 1979 by The Institute of Electrical and Electronics Engineers, Inc.