A 533 MBits/sec/wire modular bus with single or double parallel termination

Abstract

A bus with a novel modularity and termination scheme is described. The modular bus, referred to as the Y Channel, provides a bandwidth of 533 MBits/sec/wire and operates with either single or double parallel termination. Y Channel has a termination on the mother board and another termination on the optional expansion module. The impedance of the bus changes when the module is inserted. To maintain a constant voltage swing on the bus in both the cases (i.e. with and without the module), the device currents are automatically scaled. This scheme eliminates the need for dummy terminator modules that are normally used in high speed buses as place holders for future expansion. Y Channel has been verified through Spice simulations and with test hardware and has been successfully implemented in real system applications.