Automatic design of GaAs digital circuits and devices-from process and material parameters to layout

The design techniques and tools needed to build optimized digital circuits for molecular beam epitaxy (MBE) processes geared to low-noise microwave and millimeter wave applications are described. The design approach commences with input of the fundamental process parameters and design rules. From these, SPICE models suitable for use in the design of both linear and digital circuits are automatically generated. These, in turn, are used to automatically design and lay out basic logic gates. Simplified models of the gates are extracted for use with a mixed-mode simulator. This entire task, from designer entry of parameters, through generation of accurate and simplified models, to layout, can be completed in less than 90 minutes. An overview is given of the design process, the key problems that had to be addressed in its automation are described, and results for a fabricated circuit are shown.<>