There is renewed interest in the field of analog and mixed-signal circuits, especially among designers of high-speed and wireless communication systems. Due to the typical custom design approach, a large amount of time is spent laying out the large matched devices typical for such analog circuits. For complex designs, this greatly increases the probability of human error especially since analog and mixed-signal circuits are not as regular as digital ones. Schematic-driven layout (SDL) has proven to be a powerful tool for assisting custom digital design [1]. There is a need for similar SDL capabilities for analog design, to allow spending more time on circuit concepts and theory rather than on implementing and verifying (polygon pushing) cumbersome full custom layouts.

Using previously published analog layout algorithms [2], we are developing extensions to the MOSIS Design Kit (MDK) [3] to provide schematic-driven layout (SDL) capability for analog and mixed-signal designs. We are implementing device generators (in AMPLE) for inter-digitated transistors, resistors and capacitors, and for matched pairs of inter-digitated transistors, resistors and capacitors in common centroid configurations. Details on parameter formats for these device generators, as well as an example of a folded cascode amplifier design using these SDL extensions, are presented in this paper. This project was voted as being the most useful for the Higher Education Program (HEP) by the University Special Interest Group (SIG) of the Mentor User Group (MUG).

References

1. Zar, David, "Using the MOSIS Design Kit for Schematic Driven Layout", http://germanium.ee.wustl.edu/dzar/tutorials/sdl/sdl_toc.html
2. Bruce, J.D et al, "Analog Layout Using ALAS!", IEEE Journal of Solid State Circuits, vol. 30 no. 7, February 1996.
3. "MOSIS Design Kit (MDK) Information", http://germanium.ee.wustl.edu/dzar/mentor.html

Bio:
Abhimanyu Kolla is a Research Assistant at the Center for Semicustom Integrated Systems at the University of Virginia and is working towards a Master of Science degree in Electrical Engineering. He joined the University of Virginia in the Fall of 1996 on a fellowship in the Department of Electrical Engineering and he was also a teaching assistant for an introductory class in VLSI design during his first semster. Kolla received his bachelor's degree (BE) in Electronics and Communications Engineering from the Osmania University, India in May 1996. His research interests include low-power VLSI Design, design automation for integrated circuit design, analog and digital integrated circuit design, computer architecture, and Micro Electro Mechanical Systems (MEMS). He is working to extend the design automation capabilities of the Mentor Graphics tools at UVa, especially to analog integrated ciruits. He is closely involved in the development of a planar "integrated" electrode arrays for neuronal studies as an inter-disciplinary project with the Center for Biological Timing, Department of Biology at UVa.

Mircea R. Stan has been an Assistant Professor in the Electrical Engineering Department at the University of Virginia since September 1996. His graduate degrees, MS and PhD in Computer Engineering, were awarded by the University of Massachusetts at Amherst in 1994 and 1996. His research interests are in low-power VLSI, analog and digital mixed-signal circuits, FPGAs for reconfigurable architectures and embedded systems. Prior to his graduate work, Mircea accumulated more than seven years of industrial experience as an R&D Engineer in Romania, Japan and the United States. In industry, he was involved in the design of intelligent peripheral device controllers and participated in the architecture definition of a minicomputer and in the design of a professional digital voice logger. Mircea is a member of the IEEE, ACM and Usenix professional societies. He is also a member of the Phi Kappa Phi and Sigma XI honor societies and has been recently awarded an NSF CAREER grant for developing low-power design methods and tools.