A 2.5 Gb/s CMOS Add-Drop Multiplexer for ATM

Abstract

Asynchronous Transfer Mode (ATM) is used to accommodate the simultaneous transmission of voice, data and image, in an integrated manner using the same network. It is based on the transfer of fixed-length cells. In order to connect the source of information to the optical transmission line, a universal ATM functional block, the Add-Drop Multiplexer (ADM), is used. The block adds or extracts cells (53 byte words) from the high speed data bus. The objective of this work is to implement the ADM in 0.5[mu]m CMOS technology, running at 311 MHz or 2.5 Gb/s. The ADM consists of an Input Buffer which provides the selection logic for the cell extraction, an Add Module used to insert ATM cells into the high speed data bus, a Drop Module used to extract the cells from the high speed data bus and an Output Module that prepares the cells for physical transmission. The chip was designed and successfully implemented. It occupies an area of 14.7 mm2 and dissipates 4.5 W of power. The chip was tested functionally at 20 MHZ. High speed testing was also performed at 311 MHz by focusing on the critical path of the chip. A good correlation was obtained between simulation and experimental results.