MAINTAIN THE SPEED OF GaAs IN DIGITAL SYSTEMS.

Adoption of gallium-arsenide (GaAs) devices to increase the signal-processing speed of digital systems such as supercomputers is potentially a revolution in the making. For gallium arsenide, packaging of the chips and packaging to piece together the devices into an operational system pose new problems for designers. They are faced with treating interconnections as short as one quarter in. as transmission lines - not simply continuous wires or copper traces between two points. The interconnection length for which transmission-line characteristics must be considered is so short with GaAs that it becomes a factor even within a component package holding a single chip. One GaAs IC manufacturer has developed a scheme in which the GaAs die sits on top of a silicon chip that incorporates transmission-line structures and terminating resistors. All this is then placed in a leadless chip carrier.