A bipolar VLSI technology, for Oxide Isolated Logic (OXIL) circuits has been developed which combines high-frequency conventional down-transistors with inverted up-transistors which are fabricated in a common process on the same chip site. The up-transistor is especially designed to optimize I
2L circuits for high packing density, speed, and performance. High-pressure-steam oxide isolation and an up-diffused active base are combined to fabricate the up-transistor with

MHz and

, which allows I
2L delays down to 3 ns at

and 7 ns at

. The down-transistor is an oxide-isolated implanted-base transistor with an As emitter. It exhibits gains of 100-150 at

GHz and supports subnanosecond CML, high-current buffer circuitry, and linear interfacing.