Editorial

Design-Tool Evolution About to Enter a New Cycle Do systems-on-a-chip represent the next cycle of change IC design industry? Prakash Bhalerao and his company are banking on it. by Jonah McLeod

With over 20 years of experience in engineering, Prakash Bhalerao, the CEO at Ambit Design Systems (Santa Clara, CA), has seen the IC design industry undergo many cycles of change. The latest cycle just underway, and perhaps the most significant in recent times, has been the advent of 0.25-µm and smaller process technologies that enable million-gate circuits on a single chip.

As a young and ambitious engineer at Digital Equipment Corp. (Maynard, MA), Bhalerao's VAX 780 design team had to shrink a discrete logic design from 22 boards down to four to make the system manufacturable. Bhalerao created the design tools--schematic capture, simulation, and place and route tools--that Digital used to build its first gate arrays at a west coast start-up called LSI Logic Inc.

What is significant in this anecdote is that Digital used the library of standard SSI and MSI components to build in silicon what would have been done on a much larger printed circuit board. The simulation tool was the single new addition to the design flow and it allowed designers to verify that the gate array matched the wire-wrap board prototype of the circuit.

The next cycle to sweep over the design process was the synthesis tool. Much like simulation in the earlier cycle, the early synthesis tools were used to optimize existing designs. As they gained experience, designers began using the synthesis tool to automatically generate and optimize gates from HDLs.

However, Bhalerao points to another factor driving the use of synthesis tools--the steady increases in the number of gates possible on a given area of silicon. Today, volume ASIC production is performed using 0.6-ým process technology.

The typical die has a useful area of around 8x8 mm, and contains around 190 kgates. These circuits have only one major macro function--DSP, MCU, or special controller such as MPEG--some memory, and a large number of surrounding logic gates.

Another artifact in today's design methodology is the design library. Early ASIC libraries had around 200 elements. With the arrival of synthesis tools, the library still contains the core of 200 elements, but has a couple of thousand other elements--the core components, each with different drive strengths.

The advent of 0.35-µm and smaller process technologies has forced designers to confront yet another cycle of change. In this cycle, millions of gates are available and the designer must now use many more pieces of existing intellectual property--memory, DSP, MCUs, and special controllers--to create the equivalent of a circuit board on a single chip.

Bhalerao believes that the existing synthesis solutions are simply not up to the task, because they are not able to handle more than a few thousand gates at once. Thus, large circuits are divided to accommodate the tool's capacity, not to accommodate the natural hierarchy of the design. As a result, a complex graphics controller can require designers to create over 5,000 lines of scripts to control the synthesis process.

Bhalerao's new company, Ambit, claims to have developed the synthesizer for this next cycle that will sweep over the design profession. Next month, we'll hear from a designer using this next-generation tool and get his first-hand appraisal. Watch out Synopsys .

Jonah McLeod is editor-in-chief of Integrated System Design.

To voice an opinion on this or any Integrated System Design article, please e-mail your message to michael@asic.com.

integrated system design  April 1997