ISL, A FAST AND DENSE LOW-POWER LOGIC, MADE IN A STANDARD SCHOTTKY PROCESS

Integrated Schottky logic (ISL) is a new 200 mV voltage-swing LSI logic that can be made in standard Schottky processes with a double-layer metallization. It fills the gap between low-power Schottky TTL and I2L for those circuits where low-power Schottky TTL consumes too much power and takes up too much chip area, and when I2L does not attain the required speed. An ISL gate consists of a current source, a normally operated n-p-n transistor with a merged p-n-p transistor, and a set of Schottky output diodes (wired and gate). The merged p-n-p transistor clamps the n-p-n transistor and prevents the n-p-n from going too deeply into saturation. Minimum propagation delay times of 2.7 ns at 200 µA/gate are obtained, with a speed-power product of 1.2 pJ. The packing density of ISL is 120 to 180 gates/mm2. Notwithstanding the small voltage swing, the noise margins of ISL are in most cases better than the noise margins of I2L. The logic can be combined with ECL, I2L, and TTL on the same chip, and can also be made in analog processes. Proposals are given on how to make ISL in advanced oxide isolated processes in which propagation delay times below 1 ns can be obtained. Copyright © 1979 by The Institute Of Electrical And Electronics Engineers, Inc.