IBM Demonstrates 1 GHz Microprocessor

Staff -- Semiconductor International, 4/1/1998

Researchers at IBM demonstrated an experimental CMOS microprocessor that can operate at a clock speed of 1 GHz. The processor was designed at IBM's Austin Research Lab in Austin, Texas, and fabricated at IBM's Advanced Semiconductor Technology Center in East Fishkill, N.Y.

The Power PC integer processor actually achieved a clock speed of 1100 MHz (1.1 GHz) and was developed using IBM's existing 0.25 µm (250 nm) CMOS 6X technology. The microarchitecture, circuits and testing techniques resulting from this project will eventually be applied to microprocessors using IBM's recently introduced CMOS 7S "copper chip" technology.

"Circuit and architecture innovations, including the merging of some functions and performing others in parallel, enabled us to reach the 1000 MHz milestone quickly and efficiently," said Sang Dhong, the Austin-based IBM engineer who led the development effort. The design combined some functions normally performed in series, such as addition and rotation, into single operations. Dynamic logic and complex gates were used to make operations within a nanosecond possible. They also introduced a testing technique that allows the tester to operate at a fraction of the speed of the processor core.

These techniques allowed the researchers to reach the 1 GHz plateau without resorting to an artificial machine or instruction set. Jeff Burns, a researcher on the project, noted, "This is a very conventional short pipeline design. It has only four stages. You could push the frequency by dividing core operations into multiple cycles. We did not do that at all. All of our ops are single cycle ops." He continued, "We were honest in terms of implementing the machine in the way that you would in a real product level part."

A paper detailing the achievement was presented at the annual IEEE International Solid State Circuit Conference in San Francisco, Calif., in February.