Setting The Standard

Industry Consortium Chooses Electrical Engineers Transistor Model for Circuit Simulation

by Tamar Laddy

Long gone are the days when electrical engineers would solder together transistors by hand in search of an ideal circuit design. Today, integrated circuits--the building blocks of all electronic products--are simulated on computers using mathematical models of transistors.

In the quest for more accurate circuit designs, a team of Berkeley electrical engineers has developed a transistor model for circuit simulation that has been chosen by an industry consortium as the standard model for use in the design of integrated circuits.

The Berkeley model, dubbed BSIM3v3 - Berkeley Short-channel IGFET Model, version 3--is the first ever to be chosen as an industry standard.

Sematech, a research consortium of the U.S. semiconductor industry, announced the selection at a conference in Washington, D.C., in December.

With the electronic industry contributing 4 percent of the gross world product, the Berkeley model will be used by designers worldwide to create a range of products from computers, to game chips, to communication devices.

Professor Chenming Hu of electrical engineering, one of the model's developers, says the strength of BSIM3v3 lies in its ability to accurately account for variations in manufacturing. The compact model, a four-page-long equation, enables designers to account for variables such as transistor size, insulator thickness and resistance values.

The new model, says Hu, is a radical departure from previous models because it can accurately predict the effect of technological changes on transistor behavior.

"This allows a designer to predict the range of performance of a circuit under a large volume of production," Hu says.

Hu's collaborators on the model include Professor Ping Ko, postdoctoral researcher Yuhua Cheng, and graduate students Jiang Hui Huang, Mansun Chan and Kai Chen. Their research is sponsored by the Semiconductor Research Corporation, a non-profit organization and industry consortium.

Hu notes that the new model forms a much-needed link between the design and manufacture of circuits. The selection of the Berkeley model as the industry standard followed a series of international workshops and testing.

"This model may become the starting point for all circuit designs," Hu says. "There's glory and satisfaction in that, but we plan to continue to research even better models."


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