ABSTRACT
Gallium arsenide digital circuits hold the potential for higher performance than silicon devices because of the higher electron mobility in GaAs. However, no viable technology exists for the fabrication of GaAs MOSFETs. Because of the confluence of these circumstances, GaAs digital integrated circuits have been made using metal-semiconductor field-effect transistors (MESFETs). A number of circuit families have emerged but the most important is direct-coupled FET logic (DCFL).1-18
For a given lithographic technology, GaAs DCFL exhibits up to a threefold speed advantage over Si CMOS. However, this added speed comes at a cost, for two reasons: 1) GaAs wafers are smaller and more expensive, and 2) GaAs fabrication technology is more difficult and less mature than silicon technology. Also, as a consequence of the less mature GaAs processing, GaAs chips necessarily have fewer gates and less embedded memory than their silicon counterparts.
