The Cadence Design Systems backed CPF, approved as an Si2 specification in January, is one of two rival low-power IC design standards efforts. Cadence rivals including Magma, Mentor Graphics, and Synopsys are supporting the Unified Power Format (UPF), approved as an Accellera standard in late February. Efforts are now underway to converge CPF and UPF.

Magma claims that it filed its "patent exclusion" notice to protect its own technology, and is not trying to block or impede CPF. But the impact on potential CPF adopters is unclear, as are the implications for any format that results from a convergence of CPF and UPF.

CPF became publicly available Monday, March 5, following a standard 60-day patent exclusion period designed to give companies a chance to air any potential patent conflicts. According to Si2, Magma waited until the very last business day of this period to disclose that it has filed a provisional patent application that Magma believes covers aspects of the CPF specification, and is refusing to license this potential patent to CPF adopters.

"They have provided us notice that they are unwilling to commit to reasonable non-discriminatory licensing for a provisional patent, and they have provided us with the provisional patent number, but no details on what it might include," said Steve Schulz, Si2 president.

Yatin Trivedi, director of industry programs at Magma, said the patent exclusion was filed "purely to protect Magma technology." He insisted there is no intention of blocking CPF. "We are proponents of getting CPF out into the public so convergence can happen," he said. Magma was a member of Si2's Low Power Coalition (LPC) until recently, when Magma decided not to renew its membership.

Trivedi also denied Schulz's claim that Magma is refusing to license its potential patent. "We have not made any comments to that effect," Trivedi said. "That's Si2's own interpretation. They are putting more words in our mouths."

Trivedi says Magma believes that the CPF implementation may conflict with a patent Magma is filing regarding multiple voltage domains. "We don't know for sure, because we don't have access to the CPF implementation," he said. "But we had to protect ourselves by raising the exclusion." Trivedi said Magma does not believe Accellera's UPF conflicts with Magma technology.

In a positioning statement, Cadence Design Systems affirmed that it is the original developer of CPF, which is now implemented in Cadence products. "We believe this action by Magma is timed to interfere with customer adoption of the Cadence Low Power Solution," the statement said.

There's no immediate impact on CPF, Schulz said. "It's only the notice of a provisional patent, and the impact would be years away," he said. "By that point CPF will have gone through several revisions and enhancements, and could easily carve around any specific area that would be deemed a valid concept for a patent."

Nonetheless, Schulz acknowledged, the Magma move "puts a cloud over the area of low power design implementation." He also noted that CPF and UPF are very similar. Si2 declines comment on whether the Magma patent application may also impact UPF, but Schulz said, "if a patent is being claimed to apply to one, I think you would have to assume it will apply to the other as well."

"I don't think there will be any impact on CPF," Trivedi said. "If they want to implement technology we are patenting, they can look for alternative implementations or licensing negotiations. We're not claiming we have the only way to implement. There are alternatives."

The CPF 1.0 specification, meanwhile, is available at no cost at the OpenEDA web site. Download instructions, a FAQ, and further information on the Magma patent exclusion claim are available on line.