The performance required for logic gate arrays by the IBM Enterprise System/9000™ (ES/9000™) family of water-cooled processors was obtained by redesigning chips that previously consisted of emitter-coupled logic (ECL) circuits. Multiple bipolar logic circuit families were implemented for the first time on a single IBM chip by using a modular cell approach. In 60% of the ECL circuits, ac coupling in ECL gates reduced the maximum operating power per ECL circuit on ES/9000 chips by 50% and decreased the signal delay per loaded gate by 30%, to 150 ps. About 10–20% of the remaining ECL circuits were replaced by differential current switches (DCS) which dissipated less power and improved the overall chip performance. Circuits to communicate between ECL and DCS circuit families and to improve DCS circuit reliability were included on the ES/9000 chips without affecting logic function density.
Note: The Institute of Electrical and Electronics Engineers, Incorporated is distributing this Article with permission of the International Business Machines Corporation (IBM) who is the exclusive owner. The recipient of this Article may not assign, sublicense, lease, rent or otherwise transfer, reproduce, prepare derivative works, publicly display or perform, or distribute the Article.