GaAs MESFET 4 multiplied by 4 CROSSPOINT SWITCH.

Abstract

A 4 multiplied by 4 crosspoint switch for 1-GHz digital communications was designed, fabricated, and tested. The switch was designed with source-follower FET logic (SFFL). SFFL is an enhancement/depletion FET logic family with delay and power comparable to direct-coupled FET logic (DCFL), but with larger noise margins. A brief comparison of SFFL and DCFL is given. A multiplexer design in which the crosspoint switch is implemented completely logic gates was used. Design considerations such as power, speed, pulse skew, and density are discussed. The switch was fabricated using a 1- mu m self-aligned WSi//x gate MESFET process. The 4 multiplied by 4 crosspoint switch chips were tested and completely functional switches were found. The speed of the crosspoint switch was tested with a 1-Gb/s pseudorandom nonreturn-to-zero data generator. The output from the switch showed error-free switching patterns when the 1-Gb/s pseudorandom data were the input.